Search

Background: Orthostatic hypotension is associated with cardiovascular disease. It remains unclear if low standing blood pressure or high seated blood pressure is responsible for this association. We compared associations of orthostatic hypotension and hypertension with high-sensitivity cardiac troponin I and N-terminal pro-B-type natriuretic peptide., Methods: We performed a secondary analysis of the Study to Understand Fall Reduction and Vitamin D in You, a randomized controlled trial funded by the National Institute on Aging, between July 2015 and May 2019. Participants were community-dwelling adults, 70 years or older. Blood tests for high-sensitivity cardiac troponin I and N-terminal pro-B-type natriuretic peptide were drawn at visits concurrent with blood pressure measurements. Secondary analysis occurred in 2023. We determined associations between blood pressure phenotypes and cardiac biomarkers., Results: Of 674 participants (mean age 76.5 ± 5.4 years, 43% female, 17.2% Black race), 29.1% had prior cardiovascular disease. Participants with seated hypertension had 10.1% greater high-sensitivity cardiac troponin I (95% confidence interval = 3.8-16.9) and 11.0% greater N-terminal pro-B-type natriuretic peptide (4.0-18.6) than those without seated hypertension. Participants with standing hypertension had 8.6% (2.7-14.9) greater high-sensitivity cardiac troponin I and 11.8% greater N-terminal pro-B-type natriuretic peptide (5.1-18.9) than those without standing hypertension. Hypotensive phenotypes were not associated with either biomarker., Conclusions: Both seated and standing hypertension were associated with greater high-sensitivity cardiac troponin I and N-terminal pro-B-type natriuretic peptide, but hypotensive phenotypes were not. Hypoperfusion may not be the principal mechanism behind subclinical cardiac injury among older adults with orthostatic hypotension., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Objective: To systematically assess current evidence on the extent to which social relationships are associated with tooth loss in adults aged 60 years and older., Methods: A systematic literature search was conducted on PubMed, Embase, Web of Science, CINAHL and The Cochrane Library databases to identify relevant studies published from 1966 up to March 2024. Cross-sectional or cohort studies investigating the association between structural, functional and/or combined (structural and functional) components of social relationships and the number of remaining teeth or edentulism among community-dwelling or institutionalised older adults were included. Data were extracted on participants' and study characteristics, including study design, the type of measures used to assess social relationships (structural, functional, and combined), outcome measures and association estimates. The quality of the studies was assessed using the Newcastle-Ottawa Scale (NOS) for cohort studies and the adapted NOS for cross-sectional studies. The reported association between social relationships and the number of remaining teeth or edentulism was summarised using meta-analysis with robust variance estimation., Results: Twenty studies were included in the review and 12 studies (125 553 participants) in the meta-analysis. Across the 12 studies, the average odds ratio (95% confidence interval) was 1.15 (1.01-1.32), indicating a 15% higher likelihood of having a lower number of teeth or edentulism for those with weaker social relationships. The GRADE certainty of the body of evidence was low., Conclusions: Weak social relationships were associated with a lower number of teeth or edentulism in older adults. Our findings may inform potential public health approaches that target and modify social relationships to prevent and address older adults' oral diseases. Still, the directionality and the underlying mechanisms connecting social relationships and tooth loss need to be further explored by longitudinal studies with follow-up long enough for oral health outcomes or changes in social relationships to occur., Trial Registration: Protocol Registration: PROSPERO (CRD42023417845)., (© 2024 The Author(s). Community Dentistry and Oral Epidemiology published by John Wiley & Sons Ltd.)

Background: Peak expiratory flow (PEF) is a simple, inexpensive measure of respiratory effort and is a valuable predictor of health outcomes in older adults. Yet, there is a lack of epidemiological data validating PEF prediction equations among older adult populations, especially those ≥80 years. The National Health and Aging Trends Study (NHATS) is a large, nationally representative sample of U.S. adults ages ≥65 years that offers a unique opportunity to develop PEF population reference equations., Methods: Using a healthy subsample from the NHATS 2011 cohort (N = 1740; 68.9 % female; mean [SD] age = 77.0 [7.9] years), sex-specific reference equations were generated for PEF, measured via a handheld flow meter, using height and age as predictors. Reference equations for both sexes were validated against the NHATS 2015 cohort by testing measured vs. predicted PEF values. Additionally, new reference equations were compared to spirometry PEF reference equations from the National Health and Nutrition Examination Survey (NHANES)., Results: After applying NHATS 2011 reference equations to the NHATS 2015 cohort, measured vs. predicted PEF values were not significantly different (Ps > 0.05). The NHANES equations tended to slightly overestimate handheld PEF measurements in the NHATS 2015 cohort by an average of 29.3 L/min and 10.1 L/min in males and females, respectively., Conclusions: Results demonstrate the comparability of PEF reference equations from a handheld meter to spirometry reference equations in older adults. New reference equations can be applied to a traditionally undersampled population with an easily obtained and low-cost measure., Competing Interests: Declaration of competing interest JAS is a consultant for Edwards Lifesciences. MCC serves as a scientific advisory board member of AARP Staying Sharp. PTD, AB, AD, and AAW have no conflicts to disclose., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study examined the association between in vivo skeletal mitochondrial function and digital free-living physical activity patterns-a measure that summarizes biological, phenotypic, functional, and environmental effects on mobility. Among 459 participants (mean age 68 years; 55% women) in the Baltimore Longitudinal Study of Aging, mitochondrial function was quantified as skeletal muscle oxidative capacity via post-exercise phosphocreatine recovery rate (τ PCr ) in the vastus lateralis muscle of the left thigh, using 31P magnetic resonance spectroscopy. Accelerometry was collected using a 7-day, 24-h wrist-worn protocol and summarized into activity amount, intensity, endurance, and accumulation patterning metrics. Linear regression, two-part linear and logistic (bout analyses), and linear mixed effects models (time-of-day analyses) were used to estimate associations between τ PCr and each physical activity metric. Interactions by age, sex, and gait speed were tested. After covariate adjustment, higher τ PCr (or poorer mitochondrial function) was associated with lower activity counts/day (β =  - 6593.7, SE = 2406.0; p = 0.006) and activity intensity (- 81.5 counts, SE = 12.9; p < 0.001). For activity intensity, the magnitude of association was greater for men and those with slower gait speed (interaction p < 0.02 for both). Conversely, τ PCr was not associated with daily active minutes/day (p = 0.15), activity fragmentation (p = 0.13), or endurance at any bout length (p > 0.05 for all). Time-of-day analyses show participants with high τ PCr were less active from 6:00 a.m. to 12:00 a.m. than those with low τ PCr . Results indicate that poorer skeletal mitochondrial function is primarily associated with lower engagement in high intensity activities. Our findings help define the connection between laboratory-measured mitochondrial function and real-world physical activity behavior., (© 2024. The Author(s), under exclusive licence to American Aging Association.)

Background: Hearing loss is associated with restricted physical activity (PA) and impaired physical functioning, yet the relationship between severity of hearing impairment (HI) and novel PA measures in older adults with untreated HI is not well understood., Methods: Analyses included 845 participants aged ≥70 years (mean = 76.6 years) with a better-hearing ear pure-tone average (PTA) ≥30 and <70 dB in the Aging and Cognitive Health Evaluation in Elders (ACHIEVE) study who wore an ActiGraph accelerometer for 7 days. Physical functioning measures included grip strength and the Short Physical Performance Battery (SPPB). Linear regression models estimated the association by HI level (moderate or greater [PTA ≥ 40 dB] vs mild [PTA < 40 dB]) and continuous hearing with total daily activity counts, active minutes/day, activity fragmentation, grip strength, and gait speed. Logistic regression models estimated odds ratios (ORs) and 95% confidence intervals (CIs) of poor performance on the SPPB (≤6) and its subtests (≤2). Mixed-effects models estimated differences by HI level in activity by time of day., Results: Participants with moderate or greater HI had poorer physical functioning, particularly balance (OR = 2.17, 95% CI = 1.29-3.67), versus those with mild impairment. There was no association of HI level with activity quantities or fragmentation. For diurnal patterns of activity, participants with moderate or greater HI had fewer activity counts in the afternoon (12:00 pm -05:59 pm)., Conclusions: Older adults with worse hearing had shifted diurnal patterns and poorer balance performance. Exercise programs should be tailored to older adults with different levels of HI to maintain PA and physical functioning, particularly balance control., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Daily physical activity patterns differ by Alzheimer's disease (AD) status and might signal cognitive risk. It is critical to understand whether patterns are disrupted early in the AD pathological process. Yet, whether established AD risk markers (β-amyloid [Aβ] or apolipoprotein E-ε4 [APOE-ε4]) are associated with differences in objectively measured activity patterns among cognitively unimpaired older adults is unclear., Methods: Wrist accelerometry, brain Aβ (+/-), and APOE-ε4 genotype were collected in 106 (Aβ) and 472 (APOE-ε4) participants (mean age 76 [standard deviation{SD}: 8.5) or 75 [SD: 9.2] years, 60% or 58% women) in the Baltimore Longitudinal Study of Aging. Adjusted linear and function-on-scalar regression models examined whether Aβ or APOE-ε4 status was cross-sectionally associated with activity patterns (amount, variability, or fragmentation) overall and by time of day, respectively. Differences in activity patterns by combinations of Aβ and APOE-ε4 status were descriptively examined (n = 105)., Results: There were no differences in any activity pattern by Aβ or APOE-ε4 status overall. Aβ+ was associated with lower total amount and lower within-day variability of physical activity overnight and early evening, and APOE-ε4 carriers had higher total amount of activity in the evening and lower within-day variability of activity in the morning. Diurnal curves of activity were blunted among those with Aβ+ regardless of APOE-ε4 status, but only when including older adults with mild cognitive impairment/dementia., Conclusions: Aβ+ in cognitively unimpaired older adults might manifest as lower amount and variability of daily physical activity, particularly during overnight/evening hours. Future research is needed to examine changes in activity patterns in larger samples and by other AD biomarkers., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Low physical activity (PA) measured by accelerometers and low heart rate variability (HRV) measured from short-term ECG recordings are associated with worse cognitive function. Wearable long-term ECG monitors are now widely used, and some devices also include an accelerometer. The objective of this study was to evaluate whether PA or HRV measured from long-term ECG monitors was associated with cognitive function among older adults. A total of 1590 ARIC participants had free-living PA and HRV measured over 14 days using the Zio ® XT Patch [aged 72-94 years, 58% female, 32% Black]. Cognitive function was measured by cognitive factor scores and adjudicated dementia or mild cognitive impairment (MCI) status. Adjusted linear or multinomial regression models examined whether higher PA or higher HRV was cross-sectionally associated with higher factor scores or lower odds of MCI/dementia. Each 1-unit increase in the total amount of PA was associated with higher global cognition (β = 0.30, 95% CI: 0.16-0.44) and executive function scores (β = 0.38, 95% CI: 0.22-0.53) and lower odds of MCI (OR = 0.38, 95% CI: 0.22-0.67) or dementia (OR = 0.25, 95% CI: 0.08-0.74). HRV (i.e., SDNN and rMSSD) was not associated with cognitive function. More research is needed to define the role of wearable ECG monitors as a tool for digital phenotyping of dementia.

Background: Prediabetes is a highly prevalent condition that heralds an increased risk of progression to type 2 diabetes, along with associated microvascular and macrovascular complications. The Diabetes Prevention Program (DPP) is an established effective intervention for diabetes prevention. However, participation in this 12-month lifestyle change program has historically been low. Digital DPPs have emerged as a scalable alternative, accessible asynchronously and recognized by the Centers for Disease Control and Prevention (CDC). Yet, most digital programs still incorporate human coaching, potentially limiting scalability. Furthermore, existing effectiveness results of digital DPPs are primarily derived from per protocol, longitudinal non-randomized studies, or comparisons to control groups that do not represent the standard of care DPP. The potential of an AI-powered DPP as an alternative to the DPP is yet to be investigated. We propose a randomized controlled trial (RCT) to directly compare these two approaches., Methods: This open-label, multicenter, non-inferiority RCT will compare the effectiveness of a fully automated AI-powered digital DPP (ai-DPP) with a standard of care human coach-based DPP (h-DPP). A total of 368 participants with elevated body mass index (BMI) and prediabetes will be randomized equally to the ai-DPP (smartphone app and Bluetooth-enabled body weight scale) or h-DPP (referral to a CDC recognized DPP). The primary endpoint, assessed at 12 months, is the achievement of the CDC's benchmark for type 2 diabetes risk reduction, defined as any of the following: at least 5% weight loss, at least 4% weight loss and at least 150 min per week on average of physical activity, or at least a 0.2-point reduction in hemoglobin A1C. Physical activity will be objectively measured using serial actigraphy at baseline and at 1-month intervals throughout the trial. Secondary endpoints, evaluated at 6 and 12 months, will include changes in A1C, weight, physical activity measures, program engagement, and cost-effectiveness. Participants include adults aged 18-75 years with laboratory confirmed prediabetes, a BMI of ≥ 25 kg/m 2 (≥ 23 kg/m 2 for Asians), English proficiency, and smartphone users. This U.S. study is conducted at Johns Hopkins Medicine in Baltimore, MD, and Reading Hospital (Tower Health) in Reading, PA., Discussion: Prediabetes is a significant public health issue, necessitating scalable interventions for the millions affected. Our pragmatic clinical trial is unique in directly comparing a fully automated AI-powered approach without direct human coach interaction. If proven effective, it could be a scalable, cost-effective strategy. This trial will offer vital insights into both AI and human coach-based behavioral change strategies in real-world clinical settings., Trial Registration: ClinicalTrials.gov NCT05056376. Registered on September 24, 2021, https://clinicaltrials.gov/study/NCT05056376., (© 2024. The Author(s).)

Study Objectives: To compare sleep and 24-hour rest/activity rhythms (RARs) between cognitively normal older adults who are β-amyloid-positive (Aβ+) or Aβ- and replicate a novel time-of-day-specific difference between these groups identified in a previous exploratory study., Methods: We studied 82 cognitively normal participants from the Baltimore Longitudinal Study of Aging (aged 75.7 ± 8.5 years, 55% female, 76% white) with wrist actigraphy data and Aβ+ versus Aβ- status measured by [11C] Pittsburgh compound B positron emission tomography. RARs were calculated using epoch-level activity count data from actigraphy. We used novel, data-driven function-on-scalar regression analyses and standard RAR metrics to cross-sectionally compare RARs between 25 Aβ+ and 57 Aβ- participants., Results: Compared to Aβ- participants, Aβ+ participants had higher mean activity from 1:00 p.m. to 3:30 p.m. when using less conservative pointwise confidence intervals (CIs) and from 1:30 p.m. to 2:30 p.m. using more conservative, simultaneous CIs. Furthermore, Aβ+ participants had higher day-to-day variability in activity from 9:00 a.m. to 11:30 a.m. and lower variability from 1:30 p.m. to 4:00 p.m. and 7:30 p.m. to 10:30 p.m. according to pointwise CIs, and lower variability from 8:30 p.m. to 10:00 p.m. using simultaneous CIs. There were no Aβ-related differences in standard sleep or RAR metrics., Conclusions: Findings suggest Aβ+ older adults have higher, more stable day-to-day afternoon/evening activity than Aβ- older adults, potentially reflecting circadian dysfunction. Studies are needed to replicate our findings and determine whether these or other time-of-day-specific RAR features have utility as markers of preclinical Aβ deposition and if they predict clinical dementia and agitation in the afternoon/evening (i.e. "sundowning")., (© The Author(s) 2024. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Sensory impairment and brain atrophy is common among older adults, increasing the risk of dementia. Yet, the degree to which multiple co-occurring sensory impairments (MSI across vision, proprioception, vestibular function, olfactory, and hearing) are associated with brain morphometry remain unexplored. Data were from 208 cognitively unimpaired participants (mean age 72 ± 10 years; 59% women) enrolled in the Baltimore Longitudinal Study of Aging. Multiple linear regression models were used to estimate cross-sectional associations between MSI and regional brain imaging volumes. For each additional sensory impairment, there were associated lower orbitofrontal gyrus and entorhinal cortex volumes but higher caudate and putamen volumes. Participants with MSI had lower mean volumes in the superior frontal gyrus, orbitofrontal gyrus, superior parietal lobe, and precuneus compared to participants with < 2 impairments. While MSI was largely associated with lower brain volumes, our results suggest the possibility that MSI was associated with higher basal ganglia volumes. Longitudinal analyses are needed to evaluate the temporality and directionality of these associations., (© 2024. The Author(s).)

Introduction: Age-related sensory and motor impairment are associated with risk of dementia. No study has examined the joint associations of multiple sensory and motor measures on prevalence of early cognitive impairment (ECI)., Methods: Six hundred fifty participants in the Baltimore Longitudinal Study of Aging completed sensory and motor function tests. The association between sensory and motor function and ECI was examined using structural equation modeling with three latent factors corresponding to multisensory, fine motor, and gross motor function., Results: The multisensory, fine, and gross motor factors were all correlated (r = 0.74 to 0.81). The odds of ECI were lower for each additional unit improvement in the multisensory (32%), fine motor (30%), and gross motor factors (12%)., Discussion: The relationship between sensory and motor impairment and emerging cognitive impairment may guide future intervention studies aimed at preventing and/or treating ECI., Highlights: Sensorimotor function and early cognitive impairment (ECI) prevalence were assessed via structural equation modeling. The degree of fine and gross motor function is associated with indicators of ECI. The degree of multisensory impairment is also associated with indicators of ECI., (© 2024 The Authors. Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: Pain is associated with reports of restricted physical activity (PA), yet the association between musculoskeletal pain characteristics and objectively measured PA quantities and patterns in late life is not well understood., Methods: A total of 553 adults (mean age 75.8 ± 8.4 years, 54.4% women) in the Baltimore Longitudinal Study of Aging (BLSA) completed a health interview and subsequent 7-day wrist-worn ActiGraph assessment in the free-living environment between 2015 and 2020. Pain characteristics, including pain presence in 6x sites (ie, shoulders, hands/wrists, low back, hip, knees, and feet), pain laterality in each site, and pain distribution were assessed. PA metrics were summarized into total daily activity counts (TAC), activity fragmentation, active minutes/day, and diurnal patterns of activity. Linear regression models and mixed-effects models examined the association between pain characteristics and PA outcomes, adjusted for demographics and comorbidities., Results: Unilateral knee pain was associated with 184 070 fewer TAC (p = .039) and 36.2 fewer active minutes/day (p = .032) compared to those without knee pain. Older adults with shoulder pain or hand/wrist pain had more active minutes compared to those without pain (p < .05 for all). For diurnal patterns of activity, participants with knee pain had fewer activity counts during the afternoon (12:00 pm to 5:59 pm). Analyses stratified by sex showed that these associations were only significant among women., Conclusions: Our study highlights the importance of assessing pain laterality in addition to pain presence and suggests that pain interferes with multiple aspects of daily activity. Longitudinal studies are needed to assess the temporality of these findings., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Physical activity is consistently associated with better health and longer life spans. However, the extent to which length and intensity of exercise across the life course impact health outcomes relative to current activity is undefined. Participants of the Baltimore Longitudinal Study of Aging were asked to categorize their level of physical activity in each decade of life from adolescence to the current decade. In linear mixed effects models, self-reported past levels of physical activity were significantly associated with activity assessed at study visits in the corresponding decade of life either by questionnaire or accelerometry. A pattern of life course physical activity (LCPA) derived by ranking participants on reported activity intensity across multiple decades was consistent with the trajectories of activity estimated from standard physical activity questionnaires assessed at prior study visits. In multivariable linear regression models LCPA was associated with clinical characteristics, measures of body composition and indicators of physical performance independent of current physical activity. After adjustment for minutes of high intensity exercise, LCPA remained significantly associated with peak VO 2 , fasting glucose, thigh muscle area and density, abdominal subcutaneous fat, usual gait speed, lower extremity performance, and multimorbidity (all p < 0.01) at the index visit. The observed associations suggest that an estimate of physical activity across decades provides complementary information to information on current activity and reemphasizes the importance of consistently engaging in physical activity over the life course., (© 2024 The Authors. Aging Cell published by Anatomical Society and John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Sleep and physical activity, two important health behaviors, are often studied independently using different accelerometer types and body locations. Understanding whether accelerometers designed for monitoring each behavior can provide similar sleep parameter estimates may help determine whether one device can be used to measure both behaviors. Three hundred and thirty one adults (70.7 ± 13.7 years) from the Baltimore Longitudinal Study of Aging wore the ActiGraph GT9X Link and the Actiwatch 2 simultaneously on the non-dominant wrist for 7.0 ± 1.6 nights. Total sleep time (TST), wake after sleep onset (WASO), sleep efficiency, number of wake bouts, mean wake bout length, and sleep fragmentation index (SFI) were extracted from ActiGraph using the Cole-Kripke algorithm and from Actiwatch using the software default algorithm. These parameters were compared using paired t-tests, Bland-Altman plots, and Deming regression models. Stratified analyses were performed by age, sex, and body mass index (BMI). Compared to the Actiwatch, the ActiGraph estimated comparable TST and sleep efficiency, but fewer wake bouts, longer WASO, longer wake bout length, and higher SFI (all p < .001). Both devices estimated similar 1-min and 1% differences between participants for TST and SFI (β = 0.99, 95% CI: 0.95, 1.03, and 0.91, 1.13, respectively), but not for other parameters. These differences varied by age, sex, and/or BMI. The ActiGraph and the Actiwatch provide comparable absolute and relative estimates of TST, but not other parameters. The discrepancies could result from device differences in movement collection and/or sleep scoring algorithms. Further comparison and calibration is required before these devices can be used interchangeably., (© The Author(s) 2023. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction/purpose: Fatigue is an established prognostic indicator of mortality risk. It remains unknown whether fatigability anchored to a physical task is a more sensitive prognostic indicator and whether sensitivity differs by prevalent chronic conditions., Methods: A total of 1076 physically well-functioning participants 50 yr or older in the Baltimore Longitudinal Study of Aging self-reported fatigue (unusual tiredness or low energy) and had perceived fatigability assessed after a standardized treadmill walk. All-cause mortality was ascertained by proxy contact and National Death Index linkage. Cox proportional hazards models estimated associations of perceived fatigability and fatigue with all-cause mortality, adjusting for demographic and clinical covariates. Interactions by chronic conditions were also examined., Results: Each 1 SD higher in perceived fatigability, unusual tiredness, or low energy was associated with a higher relative hazard of all-cause mortality after covariate adjustment (fatigability: hazard ratio (HR), 1.18 (95% confidence interval (CI), 1.03-1.36); unusual tiredness: HR, 1.25 (95% CI, 1.08-1.44); low energy: HR, 1.27 (95% CI, 1.10-1.46)). Models had similar discrimination ( P > 0.14 for all). Perceived fatigability was associated with mortality risk among participants free of arthritis or osteoarthritis who otherwise appeared healthy (no arthritis: HR, 1.45 (95% CI, 1.15-1.84); arthritis: HR, 1.09 (95% CI, 0.92-1.30); P -interaction = 0.031). Unusual tiredness was associated with mortality among those with a history of diabetes (no diabetes: HR, 1.16 (95% CI, 0.97-1.38); diabetes: HR, 1.65 (95% CI, 1.22-2.23); P -interaction = 0.045) or pulmonary disease (no pulmonary disease: HR, 1.22 (95% CI, 1.05-1.43); pulmonary disease: HR, 2.15 (95% CI, 1.15-4.03); P -interaction = 0.034)., Conclusions: Higher perceived fatigability and fatigue symptoms were similarly associated with higher all-cause mortality, but utility differed by chronic condition. Perceived fatigability might be useful for health screening and long-term mortality risk assessment for well-functioning adults. Alternatively, self-reported fatigue seems more disease-specific with regard to mortality risk., (Copyright © 2023 by the American College of Sports Medicine.)

Background: Peripheral artery disease (PAD) is associated with lower physical activity but less is known about its association with daily patterns of activity. We examined the cross-sectional association between ankle-brachial index (ABI) and objectively measured patterns of physical activity among Hispanic/Latino adults., Methods: We analyzed data from 7 688 participants (aged 45-74 years) in the Hispanic Community Health Study/Study of Latinos. ABI was categorized as low (≤0.90, indicating PAD), borderline low (0.91-0.99), normal (1.00-1.40), and high (>1.40, indicating incompressible ankle arteries). Daily physical activity metrics derived from accelerometer data included: log of total activity counts (LTAC), total log-transformed activity counts (TLAC), and active-to-sedentary transition probability (ASTP). Average differences between ABI categories in physical activity, overall and by 4-hour time-of-day intervals, were assessed using linear regression and mixed-effects models, respectively., Results: In Hispanic/Latino adults, 5.3% and 2.6% had low and high ABIs, respectively. After adjustment, having a low compared to a normal ABI was associated with lower volume (LTAC = -0.13, p < .01; TLAC = -74.4, p = .04) and more fragmented physical activity (ASTP = 1.22%, p < .01). Having a low ABI was linked with more fragmented physical activity after 12 pm (p < .01). Having a high ABI was associated with lower volumes of activity (TLAC = -132.0, p = .03)., Conclusions: Having a low or high ABI is associated with lower and more fragmented physical activity in Hispanic/Latino adults. In adults with low ABI, physical activity is more fragmented in the afternoon to evening. Longitudinal research is warranted to expand these findings to guide targeted interventions for PAD or incompressible ankle arteries., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Combination devices to monitor heart rate/rhythms and physical activity are becoming increasingly popular in research and clinical settings. The Zio XT Patch (iRhythm Technologies, San Francisco, CA, USA) is US Food and Drug Administration (FDA)-approved for monitoring heart rhythms, but the validity of its accelerometer for assessing physical activity is unknown., Objective: To validate the accelerometer in the Zio XT Patch for measuring physical activity against the widely-used ActiGraph GT3X., Methods: The Zio XT and ActiGraph wGT3X-BT (Actigraph, Pensacola, FL, USA) were worn simultaneously in two separately-funded ancillary studies to Visit 6 of the Atherosclerosis Risk in Communities (ARIC) Study (2016-2017). Zio XT was worn on the chest and ActiGraph was worn on the hip. Raw accelerometer data were summarized using mean absolute deviation (MAD) for six different epoch lengths (1-min, 5-min, 10-min, 30-min, 1-h, and 2-h). Participants who had ≥3 days of at least 10 h of valid data between 7 a.m-11 p.m were included. Agreement of epoch-level MAD between the two devices was evaluated using correlation and mean squared error (MSE)., Results: Among 257 participants (average age: 78.5 ± 4.7 years; 59.1% female), there were strong correlations between MAD values from Zio XT and ActiGraph (average r : 1-min: 0.66, 5-min: 0.90, 10-min: 0.93, 30-min: 0.93, 1-h: 0.89, 2-h: 0.82), with relatively low error values (Average MSE × 10 6 : 1-min: 349.37 g , 5-min: 86.25 g , 10-min: 56.80 g , 30-min: 45.46 g , 1-h: 52.56 g , 2-h: 54.58 g )., Conclusions: These findings suggest that Zio XT accelerometry is valid for measuring duration, frequency, and intensity of physical activity within time epochs of 5-min to 2-h.

Background: There is inconsistent evidence on the optimal time after standing to assess for orthostatic hypotension. We determined the prevalence of orthostatic hypotension at different time points after standing in a population of older adults, as well as fall risk and symptoms associated with orthostatic hypotension., Methods: We performed a secondary analysis of the Study to Understand Fall Reduction and Vitamin D in You (STURDY), a randomized clinical trial funded by the National Institute on Aging, testing the effect of differing vitamin D3 doses on fall risk in older adults. STURDY occurred between July 2015 and May 2019. Secondary analysis occurred in 2022. Participants were community-dwelling adults, 70 years or older. In the orthostatic hypotension assessment, participants stood upright from supine position and underwent six standing blood pressure measurements (M1-M6) in two clusters of three measurements (immediately and 3 min after standing). Cox proportional hazard models were used to examine the relationship between orthostatic hypotension at each measurement and subsequent falls. Participants were followed until the earlier of their 24-month visit or study completion., Results: Orthostatic hypotension occurred in 32% of assessments at M1, and only 16% at M5 and M6. Orthostatic hypotension from average immediate (M1-3) and average delayed (M4-6) measurements, respectively, predicted higher fall risk (M1-3 = 1.65 [1.08, 2.52]; M4-6 = 1.73 [1.03, 2.91]) (hazard ratio [95% confidence interval]). However, among individual measurements, only orthostatic hypotension at M5 (1.84 [1.16, 2.93]) and M6 (1.85 [1.17, 2.91]) predicted higher fall risk. Participants with orthostatic hypotension at M1 (3.07 [1.48, 6.38]) and M2 (3.72 [1.72, 8.03]) were more likely to have reported orthostatic symptoms., Conclusions: Orthostatic hypotension was most prevalent and symptomatic immediately within 1-2 min after standing, but more informative for fall risk after 4.5 min. Clinicians may consider both intervals when assessing for orthostatic hypotension., (© 2023 The American Geriatrics Society.)

Introduction: White matter hyperintensities (WMHs) increase with age and contribute to cognitive and motor function decline. Energy costs for mobility worsen with age, as the energetic cost of walking increases and energetic capacity declines. We examined the cross-sectional associations of multiple measures of walking energetics with WMHs in mid- to late-aged adults., Methods: A total of 601 cognitively unimpaired adults (mean age 66.9 ± 15.3 years, 54% women) underwent brain magnetic resonance imaging scans and completed standardized slow- and peak-paced walking assessments with metabolic measurement (V̇O 2 ). T1-weighted scans and fluid-attenuated inversion recovery images were used to quantify WMHs. Separate multivariable linear regression models examined associations adjusted for covariates., Results: Lower slow-paced V̇O 2 (B = 0.07; P  = 0.030), higher peak-paced V̇O 2 (B = -0.10; P  = 0.007), and lower cost-to-capacity ratio (B = .12; P < 0.0001) were all associated with lower WMH volumes., Discussion: The cost-to-capacity ratio, which describes the percentage of capacity required for ambulation, was the walking energetic measure most strongly associated with WMHs., Competing Interests: All authors report no conflicts of interest. Author disclosures are available in the supporting information., (© 2023 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: To assess whether vitamin D 3 supplementation attenuates the decline in daily physical activity in low-functioning adults at risk for falls., Methods: Secondary data analyses of STURDY (Study to Understand Fall Reduction and Vitamin D in You), a response-adaptive randomized clinical trial. Participants included 571 adults aged 70 years and older with baseline serum 25(OH)D levels of 10-29 ng/mL and elevated fall risk, who wore a wrist accelerometer at baseline and at least one follow-up visit and were randomized to receive: 200 IU/day (control), 1000, 2000, or 4000 IU/day of vitamin D 3 . Objective physical activity quantities and patterns (total daily activity counts, active minutes/day, and activity fragmentation) were measured for 7-days, 24-h/day, in the free-living environment using the Actigraph GT9x over up to 24-months of follow-up., Results: In adjusted models, physical activity quantities declined (p < 0.001) and became more fragmented, or "broken up", (p = 0.017) over time. Supplementation with vitamin D 3 did not attenuate this decline. Changes in physical activity were more rapid among those with baseline serum 25(OH)D <20 ng/mL compared to those with baseline 25(OH)D levels of 20-29 ng/mL (time*baseline 25(OH)D, p < 0.05)., Conclusion: In low-functioning older adults with serum 25(OH)D levels 10-29 ng/mL, vitamin D 3 supplementation of 1000 IU/day or higher did not attenuate declines in physical activity compared with 200 IU/day. Those with baseline 25(OH)D <20 ng/mL showed accelerated declines in physical activity. Alternative interventions to supplementation are needed to curb declines in physical activity in older adults with low serum 25(OH)D., (© 2023 The American Geriatrics Society.)

Background: Wearable devices have become widespread in research applications, yet evidence on whether they are superior to structured clinic-based assessments is sparse. In this manuscript, we compare traditional, laboratory-based metrics of mobility with a novel accelerometry-based measure of free-living gait cadence for predicting fall rates., Methods: Using negative binomial regression, we compared traditional in-clinic measures of mobility (6-minute gait cadence, speed, and distance, and 4-m gait speed) with free-living gait cadence from wearable accelerometers in predicting fall rates. Accelerometry data were collected with wrist-worn Actigraphs (GT9X) over 7 days in 432 community-dwelling older adults (aged 77.29 ± 5.46 years, 59.1% men, 80.2% White) participating in the Study to Understand Fall Reduction and Vitamin D in You. Falls were ascertained using monthly calendars, quarterly contacts, and ad hoc telephone reports. Accelerometry-based free-living gait cadence was estimated with the Adaptive Empirical Pattern Transformation algorithm., Results: Across all participants, free-living cadence was significantly related to fall rates; every 10 steps per minute higher cadence was associated with a 13.2% lower fall rate (p = .036). Clinic-based measures of mobility were not related to falls (p > .05). Among higher-functioning participants (cadence ≥100 steps/minute), every 10 steps per minute higher free-living cadence was associated with a 27.7% lower fall rate (p = .01). In participants with slow baseline gait (gait speed <0.8 m/s), all metrics were significantly associated with fall rates., Conclusion: Data collected from biosensors in the free-living environment may provide a more sensitive indicator of fall risk than in-clinic tests, especially among higher-functioning older adults who may be more responsive to intervention., Clinical Trial Registration: NCT02166333., (© The Author(s) 2022. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Low physical activity is a criterion of phenotypic frailty defined as an increased state of vulnerability to adverse health outcomes. Whether disengagement from daily all-purpose physical activity is prospectively associated with frailty and possibly modified by chronic inflammation-a pathway often underlying frailty-remains unexplored., Methods: Using the Study to Understand Fall Reduction and Vitamin D in You data from 477 robust/prefrail adults (mean age = 76 ± 5 yr; 42% women), we examined whether accelerometer patterns (activity counts per day, active minutes per day, and activity fragmentation [broken accumulation]) were associated with incident frailty using Cox proportional hazard regression. Baseline interactions between each accelerometer metric and markers of inflammation that include interleukin-6, C-reactive protein, and tumor necrosis factor-alpha receptor 1 were also examined., Results: Over an average of 1.3 yr, 42 participants (9%) developed frailty. In Cox regression models adjusted for demographics, medical conditions, and device wear days, every 30 min·d -1 higher baseline active time, 100,000 more activity counts per day, and 1% lower activity fragmentation was associated with a 16% ( P = 0.003), 13% ( P = 0.001), and 8% ( P < 0.001) lower risk of frailty, respectively. No interactions between accelerometer metrics and baseline interleukin-6, C-reactive protein, or tumor necrosis factor-alpha receptor 1 were detected (interaction P > 0.06 for all)., Conclusions: Among older adults who are either robust or prefrail, constricted patterns of daily physical activity (i.e., lower total activity minutes and counts, and higher activity fragmentation) were prospectively associated with higher risk of frailty but not modified by frailty-related chronic inflammation. Additional studies, particularly trials, are needed to understand if this association is causal., (Copyright © 2022 by the American College of Sports Medicine.)

Background: Human motor function is optimised for energetic efficiency, however, age-related neurodegenerative changes affects neuromotor control of walking. Energy utilisation has been associated with motor performance, but its association with cognitive performance is unknown., Methods: The study population included 979 Baltimore Longitudinal Study of Aging participants aged $\ge$50 years (52% female, mean age: 70$\pm$10.2 years) with a median follow-up time of 4.7 years. Energy utilisation for walking was operationalised as a ratio of the energy cost of slow walking to peak walking energy expenditure during standardised tasks ('cost-ratio'). Cognitive functioning was measured using the Trail Making Tests, California Verbal Learning Test, Wechsler Adult Intelligence Scale (WAIS), letter and category fluency and card rotation tests. Linear mixed models adjusted for demographics, education and co-morbidities assessed the association between baseline cost-ratio and cognitive functioning, cross-sectionally and longitudinally. To investigate the relationship among those with less efficient energy utilisation, subgroup analyses were performed., Results: In fully adjusted models, a higher cost-ratio was cross-sectionally associated with poorer performance on all cognitive tests except WAIS (P < 0.05 for all). Among those with compromised energy utilisation, the baseline cost-ratio was also associated with a faster decline in memory (long-delay free recall: β = -0.4, 95% confidence interval [CI] = [-0.8, -0.02]; immediate word recall: β = -1.3, 95% CI = [-2.7, 0.1])., Conclusions: These findings suggest cross-sectional and longitudinal links between energy utilisation and cognitive performance, highlighting an intriguing link between brain function and the energy needed for ambulation. Future research should examine this association earlier in the life course to gauge the potential for interventive mechanisms., (© The Author(s) 2022. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Low back pain (LBP) is an important condition associated with high healthcare burden. However, the relationship of this condition with physical function (PF) and health-related quality of life (HRQoL) remains unclear. This is a cross-sectional study that aims to investigate the association between presence and intensity of non-chronic LBP with PF and HRQoL in middle-and older-aged adults. Participants answered questions about presence and intensity of LBP in the previous year, self-reported their PF and HRQoL (SF-12), and underwent objective measures of PF ([ExSPPB] including usual gait speed, narrow walk, chair stands, and standing balance), endurance performance ([EP] long-distance corridor walk) and fatigability. Generalized linear models and logistic regression models were performed. A total of 1500 participants (52.5% women, 70.3% white) aged 69.0 (SD 13.1) years were included. Of those, 642 (42.8%) reported LBP and the mean pain intensity was 4.1 (SD 2.2). After adjustments for potential confounders, presence of LBP was associated with lower self-reported PF (OR 1.73, 95% CI 1.27 to 2.37), lower physical component of HRQoL (β -0.03, 95% CI -0.04 to -0.02) and poorer chair stand performance (β -0.05, 95% CI -0.09 to -0.008). Higher intensity of LBP was associated with lower physical component of HRQoL (β -0.01, 95% CI -0.02 to -0.007), poorer ExSPPB performance (β -0.01, 95% CI -0.02 to -0.004), slower usual gait speed (β -0.01, 95% CI -0.02 to -0.004), lower total standing balance time (β -0.01, 95% CI -0.02 to -0.001) and higher fatigability (OR 1.13, 95% CI 1.01 to 1.25). The presence of non-chronic LBP was more consistently associated with lower self-reported PF, while higher intensity non-chronic LBP was associated with poorer objectively measured PF and fatigability. Collectively, this evidence suggests that although presence of pain may affect perception of function, greater pain intensity appears more strongly associated with unfavorable functional performance in mid-to-late life., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Gonçalves et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Wrist-worn accelerometry metrics are not well defined in older adults. Accelerometry data from 720 participants (mean age 70 years, 55% women) were summarized into (a) total activity counts per day, (b) active minutes per day, (c) active bouts per day, and (d) activity fragmentation (the reciprocal of the mean active bout length). Linear regression and mixed-effects models were utilized to estimate associations between age and gait speed with wrist accelerometry. Activity counts per day, daily active minutes per day, and active bouts per day were negatively associated with age among all participants, while positive associations with activity fragmentation were only observed among those ≥65 years. More activity counts, more daily active minutes, and lower activity fragmentation were associated with faster gait speed. There were baseline age interactions with annual changes in total activity counts per day, active minutes per day, and activity fragmentation (Baseline age × Time, p < .01 for all). These results help define and characterize changes in wrist-based physical activity patterns among older adults.

Background: Higher energetic costs for mobility are associated with declining gait speed, and slow gait is linked to cognitive decline and Alzheimer's disease. However, the physiological underpinnings of gait and brain health have not been well explored. We examined the associations of the energetic cost of walking with brain volume in cognitively unimpaired adults from the Baltimore Longitudinal Study of Aging., Methods: We used brain magnetic resonance imaging (MRI) data from 850 participants (mean baseline age 66.3 ± 14.5 years), of whom 451 had longitudinal MRI data (2.8 ± 1.0 MRI scans over 4.0 ± 2.0 years). The energetic cost of walking was assessed as the average energy expended (V̇O2) during 2.5 minutes of customary-paced overground walking. Multivariable linear mixed-effects models examined the associations between baseline energetic cost of walking and regional brain volumes adjusting for covariates., Results: At baseline, higher energetic cost of walking was cross-sectionally associated with lower gray and white matter volumes within the frontal, parietal, and temporal lobes, as well as hippocampal, total brain, and larger ventricular volumes (all false-discovery rate [FDR] p < .05). A baseline energetic cost of walking × time interaction demonstrated that participants with higher energetic cost of walking had faster annual decline in hippocampal volume (FDR p = .02) and accelerated annual increase in ventricular volumes (FDR p = .02)., Conclusions: The energetic cost of walking is associated with gray and white matter volumes and subsequent hippocampal atrophy and ventricular enlargement. Collectively, these data suggest the energetic cost of walking may be an early marker of neurodegeneration that contributes to the gait brain connection., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

This study compared accelerometer-measured physical activity by body placement to daily total energy expenditure (TEE) and activity energy expenditure (AEE) measured using doubly labeled water (DLW). Forty-nine adult participants wore accelerometers placed on the nondominant wrist, dominant wrist, and chest while also undergoing DLW assessments. In adjusted models, wrist-measured physical activity ( p  < 0.05), but not chest-measured physical activity ( p  > 0.05), was associated with TEE and AEE and explained a significant amount of variance that was not explained by age, sex, height, or body composition ( R 2 change = 0.04-0.08; all p  < 0.05). Accelerometer placement location is an important consideration when using accelerometry to provide information about energy expenditure.

Purpose of Review: This review assessed recent evidence on the association between objectively measured physical activity from wearable accelerometers and blood pressure (BP) in participants with metabolic syndrome (MetS)., Recent Findings: Results directly related to BP were mixed, with some studies showing positive associations and others showing null results. Importantly, several studies noted that participants with MetS demonstrated greater improvements in components of MetS after engaging in higher amounts of daily physical activity. Although this suggests greater volume of physical activity may be a means to partially mitigate hypertension in those with MetS, it remains unclear whether physical activity or inactivity (i.e., sedentary behavior) is more strongly associated with MetS. Although there may be benefit to greater volumes of daily PA among hypertensive patients with MetS, more research is needed to quantify and define the amount of daily activity needed to improve health and refine clinical recommendations. Moreover, although the evidence for improving components of MetS through engaging in physical activity is high, the amount and type(s) of physical activity needed to achieve these benefits is unclear., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Self-reported low physical activity is a defining feature of phenotypic frailty but does not adequately capture physical activity performed throughout the day. This study examined associations between accelerometer-derived patterns of routine daily physical activity and frailty., Methods: Wrist accelerometer and frailty data from 638 participants (mean age 77 [SD = 5.5] years; 44% women) were used to derive 5 physical activity metrics: active minutes/day, sedentary minutes/day, total activity counts/day, activity fragmentation (reciprocal of the average active bout length), and sedentary fragmentation (reciprocal of the average sedentary bout length). Robust, prefrail, and frail statuses were identified using the physical frailty phenotype defined as having 0, 1-2, or ≥3 of the following criterion: weight loss, exhaustion, slowness, self-reported low activity, and weakness. Frailty was collapsed into not frail (robust and prefrail) and frail, and each frailty criteria was dichotomized. Multiple logistic regression was used to model each accelerometer metric. Separate frailty criteria and interactions with age and sex were also examined., Results: With higher amounts and intensity of daily activity (more active minutes, fewer sedentary minutes, higher activity counts) and lower activity fragmentation, the odds of frailty were lower compared to robust/prefrail states (p < .02 for all). For interactions, only an age by sedentary fragmentation interaction on the odds of frailty was observed (p = .01). For each separate criteria, accelerometer metrics were associated with odds of slowness, low activity, and weakness., Conclusion: Less favorable patterns of objectively measured daily physical activity are associated with frailty and the components of slowness, low self-reported activity, and weakness., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Studies of the relationship between vitamin D and physical functioning have had inconsistent results., Methods: Physical functioning measures were collected for up to 2 years during a 2-stage, Bayesian, response-adaptive, randomized trial of 4 doses of vitamin D3 supplementation (200 [control], 1 000, 2 000, and 4 000 IU/day) to prevent falls. Two community-based research units enrolled adults aged ≥70 years, with elevated fall risk and serum 25-hydroxyvitamin D level of 10-29 ng/mL. The Pooled Higher Doses (PHD) group (≥1 000 IU/day, n = 349) was compared to the control group (n = 339) on changes in Short Physical Performance Battery (SPPB) score and its component tests, Timed Up-and-Go (TUG) test, 6-minute walk distance, and grip strength., Results: The trial enrolled 688 participants. Mean age was 77.2 years, 56.4% were male, 79.7% White, and 18.2% Black. While the PHD and control groups both lost function over time on most outcomes, the 2 groups did not show differential change overall on any outcome. Incidence of transitioning to poor functioning on gait speed, SPPB score, or TUG test did not differ by dose group., Conclusion: In older persons with low serum 25-hydroxyvitamin D level and elevated fall risk, high-dose vitamin D supplementation, ≥1 000 IU/day, did not improve measures of physical function compared to 200 IU/day., Clinical Trial Registration: NCT02166333., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Orthostatic hypotension (OH) based on a change from seated-to-standing blood pressure (BP) is often used interchangeably with supine-to-standing BP., Methods: The Study to Understand Fall Reduction and Vitamin D in You (STURDY) was a randomized trial of vitamin D3 supplementation and fall in adults aged ≥70 years at high risk of falls. OH was defined as a drop in systolic or diastolic BP of at least 20 or 10 mmHg, measured at pre-randomization, 3-, 12-, and 24-month visits with each of 2 protocols: seated-to-standing and supine-to-standing. Participants were asked about orthostatic symptoms, and falls were ascertained via daily fall calendar, ad hoc reporting, and scheduled interviews., Results: Among 534 participants with 993 paired supine and seated assessments (mean age 76 ± 5 years, 42% women, 18% Black), mean baseline BP was 130 ± 19/68 ± 11 mmHg; 62% had a history of high BP or hypertension. Mean BP increased 3.5 (SE, 0.4)/2.6 (SE, 0.2) mmHg from sitting to standing, but decreased with supine to standing (mean change: -3.7 [SE, 0.5]/-0.8 [SE, 0.3] mmHg; P-value < 0.001). OH was detected in 2.1% (SE, 0.5) of seated versus 15.0% (SE, 1.4) of supine assessments (P < 0.001). While supine and seated OH were not associated with falls (HR: 1.55 [0.95, 2.52] vs 0.69 [0.30, 1.58]), supine systolic OH was associated with higher fall risk (HR: 1.77 [1.02, 3.05]). Supine OH was associated with self-reported fainting, blacking out, seeing spots and room spinning in the prior month (P-values < 0.03), while sitting OH was not associated with any symptoms (P-values ≥ 0.40)., Conclusion: Supine OH was more frequent, associated with orthostatic symptoms, and potentially more predictive of falls than seated OH., (© 2022 The American Geriatrics Society.)

Background: Given the evolution of processing and analysis methods for accelerometry data over the past decade, it is important to understand how newer summary measures of physical activity compare with established measures., Objective: We aimed to compare objective measures of physical activity to increase the generalizability and translation of findings of studies that use accelerometry-based data., Methods: High-resolution accelerometry data from the Baltimore Longitudinal Study on Aging were retrospectively analyzed. Data from 655 participants who used a wrist-worn ActiGraph GT9X device continuously for a week were summarized at the minute level as ActiGraph activity count, monitor-independent movement summary, Euclidean norm minus one, mean amplitude deviation, and activity intensity. We calculated these measures using open-source packages in R. Pearson correlations between activity count and each measure were quantified both marginally and conditionally on age, sex, and BMI. Each measures pair was harmonized using nonparametric regression of minute-level data., Results: Data were from a sample (N=655; male: n=298, 45.5%; female: n=357, 54.5%) with a mean age of 69.8 years (SD 14.2) and mean BMI of 27.3 kg/m2 (SD 5.0). The mean marginal participant-specific correlations between activity count and monitor-independent movement summary, Euclidean norm minus one, mean amplitude deviation, and activity were r=0.988 (SE 0.0002324), r=0.867 (SE 0.001841), r=0.913 (SE 0.00132), and r=0.970 (SE 0.0006868), respectively. After harmonization, mean absolute percentage errors of predicting total activity count from monitor-independent movement summary, Euclidean norm minus one, mean amplitude deviation, and activity intensity were 2.5, 14.3, 11.3, and 6.3, respectively. The accuracies for predicting sedentary minutes for an activity count cut-off of 1853 using monitor-independent movement summary, Euclidean norm minus one, mean amplitude deviation, and activity intensity were 0.981, 0.928, 0.904, and 0.960, respectively. An R software package called SummarizedActigraphy, with a unified interface for computation of the measures from raw accelerometry data, was developed and published., Conclusions: The findings from this comparison of accelerometry-based measures of physical activity can be used by researchers and facilitate the extension of knowledge from existing literature by demonstrating the high correlation between activity count and monitor-independent movement summary (and other measures) and by providing harmonization mapping., (©Marta Karas, John Muschelli, Andrew Leroux, Jacek K Urbanek, Amal A Wanigatunga, Jiawei Bai, Ciprian M Crainiceanu, Jennifer A Schrack. Originally published in JMIR mHealth and uHealth (https://mhealth.jmir.org), 22.07.2022.)

Peak energy capacity of the whole person is associated with neurodegeneration. However, change in ability to utilize energy manifests as combination of declining peak energy capacity and rising energetic costs of mobility in mid-to-late life. We examined longitudinal associations between change in energy utilization and brain volumes. Cognitively normal participants from the Baltimore Longitudinal Study of Aging (N = 703, age = 70.4 ± 12.1 years, 54.1% women, 30% black) had concurrent data on brain volumes and energy utilization (defined as ratio of energetic cost of walking to peak energy capacity ("cost-to-capacity ratio") at ≥ 1 visit between 2008 and 2018. We performed linear mixed-effect models, adjusting for demographics, medical history and walking engagement. Average baseline cost-to-capacity ratio was 0.55 ± 0.16, with average annual increase of 0.04 ± 0.13 over 3.9 follow-up years. A 10% higher baseline cost-to-capacity ratio was associated with 2.00 cm 3 (SE = 0.44) larger baseline ventricular volume (p < 0.001), and 0.10 cm 3 (SE = 0.03) greater annual increase in ventricular volume (p = 0.004) after adjustment. Longitudinal change in cost-to-capacity ratio was not associated with brain volumes. These findings highlight, among cognitive-normal adults, poorer baseline energy utilization is associated with subsequent ventricular enlargement, an indirect measure of central brain atrophy. Future studies should explore whether early detection of worsening energy utilization may act as a marker of underlying brain atrophy., (© 2022. The Author(s).)

Context: The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a randomized trial enrolling older adults with low 25-hydroxyvitamin D [25(OH)D], demonstrated vitamin D supplementation ≥ 1000 IU/day did not prevent falls compared with 200 IU/day, with doses ≥ 2000 IU/day potentially showing safety concerns., Objective: To examine associations of achieved and change in 25(OH)D concentrations after 3 months of vitamin D supplementation with fall risk., Design: Observational analysis of trial data., Setting: General community., Participants: A total of 637 adults aged ≥ 70 with baseline 25(OH)D concentrations 10 to 29 ng/mL and elevated fall risk. Three-month on-treatment absolute 25(OH)D; absolute and relative changes from baseline., Main Outcome Measures: Incident first fall (primary) and first consequential fall (injury or sought medical care) up to 24 months. Cox models were adjusted for sociodemographics, season, Short Physical Performance Battery, and body mass index., Results: At baseline, mean (SD) age was 77.1 (5.4) years and 25(OH)D was 22.1 (5.1) ng/mL; 43.0% were women and 21.5% non-White. A total of 395 participants experienced ≥ 1 fall; 294 experienced ≥ 1 consequential fall. There was no association between absolute achieved 25(OH)D and incident first fall (30-39 vs < 30 ng/mL hazard ratio [HR], 0.93; 95% CI, 0.74-1.16; ≥40 vs < 30 ng/mL HR, 1.09; 95% CI, 0.82-1.46; adjusted overall P  = 0.67), nor absolute or relative change in 25(OH)D. For incident consequential first fall, the HR (95% CI) comparing absolute 25(OH)D ≥ 40 vs < 30 ng/mL was 1.38 (0.99-1.90)., Conclusion: Achieved 25(OH)D concentration after supplementation was not associated with reduction in falls. Risk of consequential falls may be increased with achieved concentrations ≥ 40 ng/mL., Trial Registration: ClinicalTrials.gov: NCT02166333., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society.)

Sufficient physical activity (PA) reduces the risk of a myriad of diseases and preserves physical capabilities in later life. While there have been significant achievements in mapping accelerations to real-life movements using machine learning (ML), errors continue to be common, particularly for wrist-worn devices. It remains unknown whether ML models are robust for estimating age-related loss of physical function. In this study, we evaluated the performance of ML models (XGBoost and LASSO) to estimate the hallmark measures of PA in low physical performance (LPP) and high physical performance (HPP) groups. Our models were built to recognize PA types and intensities, identify each individual activity, and estimate energy expenditure (EE) using wrist-worn accelerometer data (33 activities per participant) from a large sample of participants (n = 247, 57% females, aged 60+ years). Results indicated that the ML models were accurate in recognizing PA by type and intensity while also estimating EE accurately. However, the models built to recognize individual activities were less robust. Across all tasks, XGBoost outperformed LASSO. XGBoost obtained F1-Scores for sedentary (0.932 ± 0.005), locomotion (0.946 ± 0.003), lifestyle (0.927 ± 0.006), and strength flexibility exercise (0.915 ± 0.017) activity type recognition tasks. The F1-Scores for recognizing low, light, and moderate activity intensity were (0.932 ± 0.005), (0.840 ± 0.004), and (0.869 ± 0.005), respectively. The root mean square error for EE estimation was 0.836 ± 0.059 METs. There was no evidence showing that splitting the participants into the LPP and HPP groups improved the models’ performance on estimating the hallmark measures of physical activities. In conclusion, using features derived from wrist-worn accelerometer data, machine learning models can accurately recognize PA types and intensities and estimate EE for older adults with high and low physical function.

Background: Low serum 25-hydroxyvitamin D [25(OH)D] level is associated with a greater risk of frailty, but the effects of daily vitamin D supplementation on frailty are uncertain. This secondary analysis aimed to examine the effects of vitamin D supplementation on frailty using data from the Study To Understand Fall Reduction and Vitamin D in You (STURDY)., Methods: The STURDY trial, a two-stage Bayesian, response-adaptive, randomized controlled trial, enrolled 688 community-dwelling adults aged ≥ 70 years with a low serum 25(OH)D level (10-29 ng/mL) and elevated fall risk. Participants were initially randomized to 200 IU/d (control dose; n = 339) or a higher dose (1000 IU/d, 2000 IU/d, or 4000 IU/d; n = 349) of vitamin D3. Once the 1000 IU/d was selected as the best higher dose, other higher dose groups were reassigned to the 1000 IU/d group and new enrollees were randomized 1:1 to 1000 IU/d or control group. Data were collected at baseline, 3, 12, and 24 months. Frailty phenotype was based on number of the following conditions: unintentional weight loss, exhaustion, slowness, low activity, and weakness (≥ 3 conditions as frail, 1 or 2 as pre-frail, and 0 as robust). Cox proportional hazard models estimated the risk of developing frailty, or improving or worsening frailty status at follow-up. All models were adjusted for demographics, health conditions, and further stratified by baseline serum 25(OH)D level (insufficiency (20-29 ng/mL) vs. deficiency (10-19 ng/mL))., Results: Among 687 participants (mean age 77.1 ± 5.4, 44% women) with frailty assessment at baseline, 208 (30%) were robust, 402 (59%) were pre-frail, and 77 (11%) were frail. Overall, there was no significant difference in risk of frailty outcomes comparing the pooled higher doses (PHD; ≥ 1000 IU/d) vs. 200 IU/d. When comparing each higher dose vs. 200 IU/d, the 2000 IU/d group had nearly double the risk of worsening frailty status (HR = 1.89, 95% CI: 1.13-3.16), while the 4000 IU/d group had a lower risk of developing frailty (HR = 0.22, 95% CI: 0.05-0.97). There were no significant associations between vitamin D doses and frailty status in the analyses stratified by baseline serum 25(OH)D level., Conclusions: High dose vitamin D supplementation did not prevent frailty. Significant subgroup findings might be the results of type 1 error., Trial Registration: ClinicalTrials.gov: NCT02166333 ., (© 2022. The Author(s).)

Although physical activity (PA) is an important determinant of exercise capacity, the association between these constructs is modest. The authors investigated the associations of self-reported and objectively measured PA with maximal and submaximal tests of exercise capacity. Participants aged ≥40 years (N = 413; 49.6% female) completed a PA questionnaire, wore a uniaxial accelerometer (5.2 ± 1.1 days), and performed maximal (cardiopulmonary exercise test [CPET]) and submaximal (long-distance corridor walk) tests with indirect calorimetry (oxygen consumption, V˙O2). Linear regression models were fitted to assess the variation in exercise capacity explained (partial eta squared, η2) by PA variables. Accelerometer-measured vigorous (η2 = 22% female; η2 = 16% male) and total PA (η2 = 17% female; η2 = 13% male) explained the most variance in CPET V˙O2 (p < .001). All η2 values were lower for long-distance corridor walk V˙O2 (η2 ≤ 11%). Age contributed more to CPET V˙O2 than any PA variable in males (η2 = 32%), but not in females (η2 = 19%). Vigorous and total PA play important roles in CPET V˙O2 in mid to late life.

Background: Vitamin D3 supplementation is considered a potential intervention to prevent orthostatic hypotension (OH) based on observational evidence that vitamin D levels are inversely associated with OH. With data from The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a double-blind, randomized, response-adaptive trial, we determined if higher doses of vitamin D3 reduced risk of OH., Methods: STURDY tested the effects of higher (1,000+ IU/day, i.e., 1,000, 2,000, and 4,000 IU/day combined) vs. lower-dose vitamin D3 (200 IU/day, comparison) on fall risk in adults ages 70 years and older with low serum 25-hydroxyvitamin D (25(OH)D, 10-29 ng/ml). OH was determined at baseline, 3, 12, and 24 months by taking the difference between seated and standing blood pressure (BP). OH was defined as a drop in systolic or diastolic BP of at least 20 or 10 mm Hg after 1 minute of standing. Participants were also asked about OH symptoms during the assessment and the preceding month., Results: Among 688 participants (mean age 77 [SD, 5] years; 44% women; 18% Black), the mean baseline systolic/diastolic BP was 130 (19)/67 (11) mm Hg, serum 25(OH)D was 22.1 (5.1) ng/ml, and 2.8% had OH. There were 2,136 OH assessments over the maximum 2-year follow-up period. Compared with 200 IU/day, 1,000+ IU/day was not associated with seated, standing, or orthostatic BP, and it did not lower risk of OH or orthostatic symptoms., Conclusions: These findings do not support use of higher doses of vitamin D3 supplementation as an intervention to prevent OH., Clinical Trials Registration: Trial Number NCT02166333., (© American Journal of Hypertension, Ltd 2021. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The health benefits of physical activity (PA) have been widely recognized, yet traditional measures of PA, including questionnaires and category-based assessments of volume and intensity, provide only broad estimates of daily activities. Accelerometers have advanced epidemiologic research on PA by providing objective and continuous measurement of PA in free-living conditions. Wrist-worn accelerometers have become especially popular because of low participant burden. However, the validity and reliability of wrist-worn devices for adults have yet to be summarized. Moreover, accelerometer data provide rich information on how PA is accumulated throughout the day, but only a small portion of these rich data have been used by researchers. Last, new methodological developments are emerging that aim to overcome some of the limitations of accelerometers. In this review, we provide an overview of accelerometry research, with a special focus on wrist-worn accelerometers. We describe briefly how accelerometers work; summarize the validity and reliability of wrist-worn accelerometers; discuss the benefits of accelerometers, including measuring light-intensity PA; and discuss pattern metrics of daily PA recently introduced in the literature. A summary of large-scale cohort studies and randomized trials that implemented wrist-worn accelerometry is provided. We conclude the review by discussing new developments and directions of research using accelerometers, with a focus on wrist-worn accelerometers., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Gradual disengagement from daily physical activity (PA) could signal present or emerging mild cognitive impairment (MCI) or Alzheimer's disease (AD)., Objective: This study examined whether accelerometry-derived patterns of everyday movement differ by cognitive diagnosis in participants of the Baltimore Longitudinal Study of Aging (BLSA)., Methods: Activity patterns, overall and by time-of-day, were cross-sectionally compared between participants with adjudicated normal cognition (n = 549) and MCI/AD diagnoses (n = 36; 5 participants [14%] living with AD) using covariate-adjusted regression models., Results: Compared to those with normal cognition, those with MCI/AD had 2.1% higher activity fragmentation (SE = 1.0%, p = 0.036) but similar mean total activity counts/day (p = 0.075) and minutes/day spent active (p = 0.174). Time-of-day analyses show MCI/AD participants had lower activity counts and minutes spent active during waking hours (6:00 am-5:59 pm; p < 0.01 for all). Also, they had lower activity fragmentation from 12:00-5:59 am (p < 0.001), but higher fragmentation from 12:00-5:59 pm (p = 0.026)., Conclusion: Differences in the timing and patterns of physical activity throughout the day linked to MCI/AD diagnoses warrant further investigation into potential clinical utility.

Background: Vision loss is associated with increased risk of falls and restricted physical activity, yet the relationship between multiple vision measures and objectively measured physical activity, especially activity patterns, in mid-to-late life is not well understood., Method: This study included 603 participants aged 50 years and older (mean age = 73.5) in the Baltimore Longitudinal Study of Aging who had the following assessments: presenting and best-corrected visual acuity, contrast sensitivity, visual fields, stereo acuity, and free-living physical activity using a wrist-worn ActiGraph accelerometer for 7 days. Linear regression models were used to examine the association between vision measures and daily activity counts, active minutes, and activity fragmentation (defined as an active-to-sedentary transition probability), adjusting for potential confounders. Mixed-effects models estimated differences in activity by time of day comparing those with and without each visual impairment., Results: In the fully adjusted model, worse presenting visual acuity, contrast sensitivity, and visual fields were associated with fewer activity counts, less active time, and more fragmented activity patterns (p < .05 for all). Participants with presenting or best-corrected visual acuity impairment had 19.2 and 29.3 fewer active minutes (p = .05 and p = .03, respectively) per day. Visual field impairment was associated with 268 636 fewer activity counts (p = .02), 46.2 fewer active minutes (p = .02) per day, and 3% greater activity fragmentation (p = .009). Differences in activity levels tended to be greatest from 6 am to 6 pm (p < .05)., Conclusions: Older adults with visual impairment have restricted and more fragmented patterns of daily activity. Longitudinal studies to quantify the long-term impacts of visual impairments on activity decline are warranted., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Importance: Among older people, slow walking is an early indicator of risk for Alzheimer disease (AD). However, studies that have assessed this association have not considered that slow walking may have different causes, some of which are not necessarily associated with higher AD risk., Objective: To evaluate whether low activity fragmentation among older adults with slow gait speed indicates neurological causes of slow walking that put these individuals at higher risk of AD., Design, Setting, and Participants: This prospective cohort study performed survival analyses using data from the Baltimore Longitudinal Study of Aging. Participants included 520 initially cognitively normal persons aged 60 years or older. New diagnoses of mild cognitive impairment (MCI) or AD were adjudicated during a mean (SD) follow-up of 7.3 (2.7) years. Initial assessment of gait speed and activity fragmentation occurred from January 3, 2007, to May 11, 2015, with follow-up completed on December 31, 2020. Data were analyzed from February 1 to May 15, 2021., Exposures: Gait speed for 6 m and activity fragmentation assessed by accelerometry., Main Outcomes and Measures: Associations of gait speed, activity fragmentation, and their interaction with incident MCI/AD were evaluated using Cox proportional hazards models, adjusted for covariates., Results: Among the 520 participants (265 women [51.0%]; 125 Black participants [24.0%]; 367 White participants [70.6%]; mean [SD] age, 73 [8] years), MCI/AD developed in 64 participants. Each 0.05-m/s slower gait was associated with a 7% increase in risk of developing MCI/AD (hazard ratio [HR], 1.07 [95% CI, 1.00-1.15]; P = .04). Activity fragmentation alone was not associated with MCI/AD risk (HR, 0.83 [95% CI, 0.56-1.23]; P = .35), but there was a significant interaction between gait speed and activity fragmentation (HR, 0.92 [95% CI, 0.87-0.98]; P = .01). At low activity fragmentation (-1 SD), each 0.05-m/s slower gait speed was associated with a 19% increase in hazard of developing MCI/AD (HR, 1.19 [95% CI, 1.07-1.32]), whereas at higher activity fragmentation (+1 SD), gait speed was not associated with MCI/AD (HR, 1.01 [95% CI, 0.93-1.10]). Among participants with slow gait, higher activity fragmentation was associated with higher odds of having lower extremity osteoarthritis (odds ratio, 1.31 [95% CI, 1.01-1.69]) and less decline in pegboard dominant hand performance (β = 0.026 [SE, 0.009]; P > .05)., Conclusions and Relevance: These findings suggest that frequent rests among older adults with slow gait speed are associated with lower risk of future MCI/AD and that this behavioral strategy is associated with a lower likelihood of subclinical neurological impairment.

Background/objectives: To assess whether vitamin D supplementation prevents specific fall subtypes and sequelae (e.g., fracture)., Design: Secondary analyses of STURDY (Study to Understand Fall Reduction and Vitamin D in You)-a response-adaptive, randomized clinical trial., Setting: Two community-based research units., Participants: Six hundred and eighty-eight participants ≥70 years old with elevated fall risk and baseline serum 25-hydroxyvitamin D levels of 10-29 ng/ml., Intervention: 200 IU/day (control), 1000 IU/day, 2000 IU/day, or 4000 IU/day of vitamin D3., Measurements: Outcomes included repeat falls and falls that were consequential, were injurious, resulted in emergency care, resulted in fracture, and occurred either indoors or outdoors., Results: After adjustment for multiple comparisons, the risk of fall-related fracture was greater in the pooled higher doses (≥1000 IU/day) group compared with the control (hazard ratio [HR] = 2.66; 95% confidence interval [CI]:1.18-6.00). Although not statistically significant after multiple comparisons adjustment, time to first outdoor fall appeared to differ between the four dose groups (unadjusted p for overall difference = 0.013; adjusted p = 0.222), with risk of a first-time outdoor fall 39% lower in the 1000 IU/day group (HR = 0.61; 95% CI: 0.38-0.97; unadjusted p = 0.036; adjusted p = 0.222) and 40% lower in the 2000 IU/day group (HR = 0.60; 95%CI 0.38-0.97; p = 0.037; adjusted p = 0.222), each versus control., Conclusion: Vitamin D supplementation doses ≥1000 IU/day might have differential effects on fall risk based on fall location and fracture risk, with the most robust finding that vitamin D doses between 1000 and 4000 IU/day might increase the risk of first time falls with fractures. Replication is warranted, given the possibility of type 1 error., (© 2021 The Authors. Journal of the American Geriatrics Society published by Wiley Periodicals LLC on behalf of The American Geriatrics Society.)

Study Objective: To examine associations of personality dimensions and facets with insomnia symptoms in a community sample of older adults., Methods: We studied 1049 participants aged 60-97 years in the Baltimore Longitudinal Study of Aging. Personality was assessed by the Revised NEO Personality Inventory (NEO-PI-R), and insomnia symptom severity was measured by the Women's Health Initiative Insomnia Rating Scale (WHIIRS)., Results: Adjusting for demographic characteristics, higher neuroticism, lower conscientiousness, and lower extraversion were associated with greater insomnia symptom severity. These associations remained significant for neuroticism and conscientiousness when further adjusting for depressive symptoms and comorbidities. Higher scores on neuroticism facets Anxiety, Angry Hostility, and Depression, and lower scores on conscientiousness facets Competence, Order, and Achievement Striving and on agreeableness facet Altruism were associated with greater insomnia symptom severity in fully adjusted models. Results were similar among cognitively normal older adults (N = 966), except higher scores on extraversion facets Warmth and Assertiveness associated with lower insomnia symptom severity, and agreeableness facet Altruism was unassociated., Conclusion: Among older adults, insomnia symptoms appear partially related to personality, with persons higher in neuroticism experiencing greater insomnia symptom severity, and those higher in conscientiousness experiencing lower insomnia symptom severity. Exploring facets of the Big-Five dimensions may provide additional insight regarding the etiology and resolution of sleep disturbance, and some of these associations may differ based on cognitive status. Future studies should investigate the hypothesis that sleep impairment mediates part of the association between specific personality traits and health-related outcomes., (© Sleep Research Society 2021. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Physical activity becomes increasingly fragmented with age, which may be an early marker of functional decline. Energetic cost of walking and energy capacity are also linked with functional decline, but their associations with activity fragmentation, and the potential modifying roles of total daily physical activity and age, remains unclear., Method: A total of 493 participants (50-93 years) from the Baltimore Longitudinal Study of Aging underwent measures of energetic cost of usual-paced overground walking (mL/kg/m), energy demand during slow walking (mL/kg/min) on a treadmill (0.67 m/s, 0% grade), and average peak walking energy expenditure (mL/kg/min) during a fast-paced 400-m walk. A ratio of slow walking to peak walking energy expenditure ("cost-to-capacity ratio") was calculated. Activity fragmentation was quantified as an active-to-sedentary transition probability (ASTP) using Actiheart accelerometer data. Linear regression models with ASTP as the dependent variable were used to test whether poorer energy cost and capacity were associated with higher ASTP and whether the associations differed by daily physical activity or age., Results: After adjusting for demographics, body composition, comorbidities, and daily physical activity, every 10% higher cost-to-capacity ratio was associated with 0.4% greater ASTP (p = .005). This association was primarily driven by the least active participants (pinteraction = .023). Peak walking energy expenditure was only associated with ASTP among participants aged ≥70 years., Conclusions: Higher cost-to-capacity ratio and lower energy capacity may manifest as more fragmented physical activity, especially among those less active or aged ≥70 years. Future studies should examine whether an increasing cost-to-capacity ratio or declining energy capacity predicts subsequent activity fragmentation., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Physical fatigability, or susceptibility to physical fatigue, is strongly associated with aging, disease, and disability. Over the lifecourse, personality traits are also connected to numerous age-related vulnerabilities and resistance-yet, their longitudinal association with fatigability remains unknown. Well-functioning community-dwelling volunteers aged ≥50 (N = 995) from the Baltimore Longitudinal Study of Aging (BLSA) were assessed over an average of 2 years on personality traits (NEO-PI-R; openness, conscientiousness, extraversion, agreeableness, and neuroticism) and perceived fatigability [Borg Rating of Perceived Exertion (RPE) after a 5-min slow treadmill walk; 6 (low) to 20 (high) exertion]. Linear and multinomial logistic regression models examined cross-sectional associations [treating fatigability continuously and by RPE category: low (6-7), intermediate (8-9), and high (10+)]. Generalized estimating equations (GEE) tested longitudinal associations. All models were adjusted for demographics and comorbid conditions. In cross-sectional models, openness, β = -.09 RPE (SE =.03); p < .01, conscientiousness, β = -.07 (.03); p < .05, and extraversion, β = -.10 (.03); p < .01, were negatively associated with fatigability. In parallel, lower openness, OR: .98, 95% CI [.96-1.00], conscientiousness, OR: .98, 95% CI [.96-1.00], and extraversion, OR: .97, 95% CI [.95-.99], corresponded with higher odds of having high versus low fatigability. In longitudinal models (mean follow-up time 2 ± 2 years), openness, conscientiousness, and extraversion associations remained significant and did not change over time (Trait × Year p values > .34). Together, findings suggest that personality plays a role in the perceived tolerance of fatigue in well-functioning older adults. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Introduction: Higher energetic costs for mobility predict gait speed decline. Slow gait is linked to cognitive decline and Alzheimer's disease (AD). Whether the energetic cost of walking is linked to AD pathology is unknown. We investigated the cross-sectional association between the energetic cost of walking, gait speed, and amyloid beta (Aβ) status (+/-) in older adults., Methods: One hundred forty-nine cognitively normal adults (56% women, mean age 77.5 ± 8.4 years) completed customary-paced walking assessments with indirect calorimetry and 11 C-Pittsburgh compound B positron emission tomography. Logistic regression models examined associations adjusted for demographics, body composition, comorbid conditions, and apolipoprotein E ε4., Results: Each 0.01 mL/kg/m greater energy cost was associated with 18% higher odds of being Aβ+ (odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.04 to 1.34; P  = .011). These findings were not observed when investigating gait speed (OR = 0.99; 95% CI: 0.97 to 1.01; P  = .321)., Discussion: High energetic cost of walking is linked to AD pathology and may be a potential target for therapeutic intervention., Competing Interests: All authors report no conflicts of interest., (© 2021 The Authors. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring published by Wiley Periodicals, LLC on behalf of Alzheimer's Association.)

Background: Larger brain volumes are often associated with more free-living physical activity (PA) in cognitively normal older adults. Yet, whether greater brain volumes are associated with more favorable (less fragmented) PA patterns, and whether this association is stronger than with total PA, remains unknown., Methods: Brain magnetic resonance imaging and wrist-worn accelerometer data were collected in 301 participants (mean age = 77 [SD = 7] years, 59% women) enrolled in the Baltimore Longitudinal Study of Aging. Linear regression models were fit to examine whether brain volumes (cc) were cross-sectionally associated with: (a) total daily PA minutes and (b) activity fragmentation (mean number of PA bouts / total PA minutes × 100). Sensitivity analyses were conducted by adjusting for counterpart PA variables (eg, fragmentation covariate included in the PA minutes model)., Results: Greater white matter volumes in the parietal and temporal lobes were associated with higher daily PA minutes (2.6 [SE = 1.0] and 3.8 [0.9] min/day, respectively; p < .009 for both) after adjusting for demographics, behavioral factors, medical conditions, gait speed, apolipoprotein E e4 status, and intracranial volume. Greater temporal white matter volume was associated with lower fragmentation (-0.16% [0.05], p = .003). In sensitivity analyses, observed associations between brain volumes and daily PA minutes remained significant while associations with fragmentation no longer remained significant., Conclusions: Our results suggest white matter brain structure in cognitively normal older adults is associated with the total amount of PA and, to a lesser extent, the PA accumulation patterns. More work is needed to elucidate the longitudinal relationship between brain structure and function and PA patterns with aging., (© The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Accelerometer-based fitness trackers and smartwatches are proliferating with incessant attention towards health tracking. Despite their growing popularity, accurately measuring hallmark measures of physical activities has yet to be accomplished in adults of all ages. In this work, we evaluated the performance of four machine learning models: decision tree, random forest, extreme gradient boosting (XGBoost) and least absolute shrinkage and selection operator (LASSO), to estimate the hallmark measures of physical activities in young (20-50 years), middle-aged (50-70 years], and older adults (70-89 years]. Our models were built to recognize physical activity types, recognize physical activity intensities, estimate energy expenditure (EE) and recognize individual physical activities using wrist-worn tri-axial accelerometer data (33 activities per participant) from a large sample of participants ( n = 253, 62% women, aged 20-89 years old). Results showed that the machine learning models were quite accurate at recognizing physical activity type and intensity and estimating energy expenditure. However, models performed less optimally when recognizing individual physical activities. F1-Scores derived from XGBoost's models were high for sedentary (0.955-0.973), locomotion (0.942-0.964) and lifestyle (0.913-0.949) activity types with no apparent difference across age groups. Low (0.919-0.947), light (0.813-0.828) and moderate (0.846-0.875) physical activity intensities were also recognized accurately. The root mean square error range for EE was approximately 1 equivalent of resting EE [0.835-1.009 METs]. Generally, random forest and XGBoost models outperformed other models. In conclusion, machine learning models to label physical activity types, activity intensity and energy expenditure are accurate and there are minimal differences in their performance across young, middle-aged and older adults.