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Purpose: Habitual strength and power-demanding activities of daily life may support the maintenance of adequate lower extremity functioning with aging, but this has been sparingly explored. Hence, we examined whether the characteristics of free-living sit-to-stand (STS) transitions predict a decline in lower extremity functioning over a 4-yr follow-up. Methods: A total of 340 community-dwelling older adults (60% women; age 75, 80, or 85 yr) participated in this prospective cohort study. At baseline, a thigh-worn accelerometer was used continuously (3-7 d) to monitor the number and intensity of free-living STS transitions. A decline in lower extremity functioning was defined as a drop of ≥2 points in the Short Physical Performance Battery (SPPB) from baseline to follow-up. Maximal isometric knee extension strength was measured in the laboratory. Results: Eighty-five participants (75%women) declined in SPPB over 4 yr. After adjusting for age, sex, and baseline SPPB points, higher free-living peak STS angular velocity (odds ratio (OR), 0.70; 95% confidence interval (CI), 0.52-0.92, per 20°⋅s-1 increase) protected against a future decline. When adjusting the model for maximal isometric knee extension strength, the statistical significance was attenuated (OR = 0.72; 95% CI = 0.54-0.96, per 20°⋅s-1 increase). Conclusions: Performing STS transitions at higher velocities in the free-living environment can prevent a future decline in lower extremity function. This indicates that changes in daily STS behavior may be useful in the early identification of functional loss. Free-living peak STS angular velocity may be a factor underlying the longitudinal association of lower extremity strength and performance. [ABSTRACT FROM AUTHOR]

Athlete load monitoring using upper back-mounted global navigation satellite system (GNSS) player tracking is common within many team sports. However, accelerometer-based load monitoring may provide information that cannot be achieved with GNSS alone. This review focuses on the accelerometer-based metrics quantifying the accumulation of accelerations as an estimation of athlete training load, appraising the validity and reliability of accelerometer use in upper back-mounted GNSS player tracking systems, the accelerometer-based metrics, and their potential for application within athlete monitoring. Reliability of GNSS-housed accelerometers and accelerometer-based metrics are dependent on the equipment model, signal processing methods, and the activity being monitored. Furthermore, GNSS unit placement on the upper back may be suboptimal for accelerometer-based estimation of mechanical load. Because there are currently no feasible gold standard comparisons for field-based whole-body biomechanical load, the validity of accelerometer-based load metrics has largely been considered in relation to other measures of training load and exercise intensity. In terms of convergent validity, accelerometer-based metrics (e.g., Play- erLoad, Dynamic Stress Load, Body Load) have correlated, albeit with varying magnitudes and certainty, with measures of internal physiological load, exercise intensity, total distance, collisions and impacts, fatigue, and injury risk and incidence. Currently, comparisons of these metrics should not be made between athletes because of mass or technique differences or between manufacturers because of processing variations. Notable areas for further study include the associations between accelerometer- based metrics and other parts of biomechanical load-adaptation pathways of interest, such as internal biomechanical loads or methods of manipulating these metrics through effective training design. [ABSTRACT FROM AUTHOR]

The quantification of training loads (TLs) is essential for optimizing jump performance and reducing the occurrence of injuries. This study aimed to (a) propose a new method for quantifying TLs in explosive exercises, (b) determine the nature of the relationship between TLs dynamics and injury occurrence, and (c) assess a TLcritical for training schedule purposes, above which the risk of injury occurrence becomes unacceptable. This study was conducted with 11 male volleyball players on a national team during a 5-month international competitive period. The proposed new method for quantifying TLs is based on a weighting factor applied to relative jumping intensities, determined by the number of sustainable jumps and their intensities measured by G-Vert accelerometer. The relationship between TLs dynamics and injury occurrence was assessed using a variable dose-response model. A high coefficient of determination was found between the maximum number of jumps possible and their intensities (r² = 0.94 ± 0.14, p < 0.001), indicating a strong physiological relationship between jumping intensities and the constraints imposed. The occurrence of injury was dependent on TLs dynamics for 2 players (r² = 0.26 ± 0.01; p < 0.001). The TLcritical corresponded to 11 jumps over 80% of maximum jump height during games and approximately 130 jumps at <80% of maximal jump height. The present study proposes a new approach for quantifying supramaximal exercises and provides tools for training schedules and the prevention of volleyball injuries. [ABSTRACT FROM AUTHOR]

Introduction: Physical activity, sedentary behavior, and sleep, that is, 24-h movement behaviors, often change in the transition from work to retirement, which may affect cardiometabolic health. This study investigates the longitudinal associations between changes in 24-h movement behaviors and cardiometabolic biomarkers during the retirement transition. Methods: Retiring public sector workers (n = 212; mean (SD) age, 63.5 (1.1) yr) from the Finnish Retirement and Aging study used a thigh-worn Axivity accelerometer and filled out a diary to obtain data on daily time spent in sedentary behavior (SED), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA), and sleep before and after retirement (1 yr in-between). Cardiometabolic biomarkers, including LDL-cholesterol, HDL-cholesterol, total/HDL-cholesterol ratio, triglycerides, C-reactive protein, fasting glucose, and insulin, were measured. Associations between changes in 24-h movement behaviors and cardiometabolic biomarkers were analyzed using compositional robust regression and isotemporal substitution analysis. Results: Increasing LPA in relation to remaining behaviors was associated with an increase in HDL-cholesterol and decrease in total/HDL-cholesterol ratio ( P < 0.05 for both). For instance, reallocation of 30 min from sleep/SED to LPA was associated with an increase in HDL-cholesterol by 0.02 mmol⋅L-1. Moreover, increasing MVPA in relation to remaining behaviors was associated with a decrease in triglycerides ( P = 0.02). Reallocation of 30 min from SED/sleep to MVPA was associated with 0.07-0.08 mmol⋅L-1 decrease in triglycerides. Findings related to LDL-cholesterol, C-reactive protein, fasting glucose, and insulin were less conclusive. Conclusions: During the transition from work to retirement, increasing physical activity at the expense of passive behaviors was associated with a better lipid profile. Our findings suggest that life transitions like retirement could be utilized more as an optimal time window for promoting physical activity and health. [ABSTRACT FROM AUTHOR]

Monitoring training load is essential for optimizing the performance of athletes, allowing practitioners to assess training programs, monitor athlete progress, and minimize the risk of injury and overtraining. However, there is no universal method for training load monitoring, and the adoption of wearable global positioning system (GPS) and accelerometer technology in team sports has increased the volume of data and, therefore, the number of possible approaches. This survey investigated the usage, applications, and understanding of this technology by team sports practitioners. Seventy-two practitioners involved in team and athlete performance monitoring using GPS and accelerometer technology completed the survey. All respondents reported supporting the use of GPS technology in their sport, with 70.8% feeling that GPS technology is important for success. Results showed that 87.5% of respondents use data from wearable technology to inform training prescription, although only 50% use the data to influence decisions in competition. In addition, results showed that GPS metrics are used more than accelerometer-derived metrics; however, both are used regularly. Discrepancies in accelerometer usage highlighted concerns about practitioners' understanding of accelerometer-derived metrics. This survey gained insight into usage, application, understanding, practitioner needs, and concerns and criticisms surrounding the use of GPS and accelerometer metrics for athlete load monitoring. Such information can be used to improve the implementation of this technology in team sport monitoring and highlight gaps in the literature that will help to design future studies to support practitioner needs. [ABSTRACT FROM AUTHOR]

Background: Chinese American immigrants have been underrepresented in health research partly due to challenges in recruitment. Objectives: This study aims to describe recruitment and retention strategies and report adherence in a 7-day observational physical activity study of Chinese American immigrants with prior gestational diabetes during the COVID-19 pandemic. Methods: Foreign-born Chinese women aged 18--45 years, with a gestational diabetes index pregnancy of 0.5--5 years, who were not pregnant and had no current diabetes diagnosis were recruited. They wore an accelerometer for 7 consecutive days and completed an online survey. Multiple recruitment strategies were used: (a) culturally and linguistically tailored flyers, (b) social media platforms (e.g., WeChat [a popular Chinese platform] and Facebook), (c) near-peer recruitment and snowball sampling, and (d) a study website. Retention strategies included flexible scheduling and accommodation, rapid communications, and incentives. Adherence strategies included a paper diary and/or automated daily text reminders with a daily log for device wearing, daily email reminders for the online survey, close monitoring, and timely problem-solving. Results: Participants were recruited from 17 states; 108 were enrolled from August 2020 to August 2021. There were 2,479 visits to the study webpage, 194 screening entries, and 149 inquiries about the study. Their mean age was 34.3 years, and the mean length of U.S. stay was 9.2 years. Despite community outreach, participants weremainly recruited fromsocialmedia (e.g., WeChat). The majority were recruited via near-peer recruitment and snowball sampling. The retention rate was 96.3%; about 99% had valid actigraphy data, and 81.7% wore the device for 7 days. The majority of devices were successfully returned, and the majority completed the online survey on time. Discussion: We demonstrated the feasibility of recruiting and retaining a geographically diverse sample of Chinese American immigrants with prior gestational diabetes during the COVID-19 pandemic. Recruiting Chinese immigrants via social media (e.g., WeChat) is a viable approach. Nonetheless, more inclusive recruitment strategies are needed to ensure broad representation from diverse socioeconomic groups of immigrants. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to examine the associations of 24-h movement behaviors (moderate to vigorous physical activity [MVPA], light physical activity [LPA], sedentary behavior [SB], and sleep) with age-, sex-, and race-specific a real bone mineral density (aBMD) z-score parameters at clinical sites in young pediatric cancer survivors. Methods: This cross-sectional multicenter study was carried out within the iBoneFIT framework in which 116 young pediatric cancer survivors (12.1 ± 3.3 yr old; 42%female) were recruited. We obtained anthropometric and body composition data (i.e., body mass, stature, body mass index, and region-specific lean mass), time spent in movement behaviors over at least seven consecutive 24-h periods (wGT3x-BT accelerometer, ActiGraph), and aBMD z-score parameters (age-, sex-, and race-specific total at the body, total hip, femoral neck and lumbar spine). Survivors were classified according to somatic maturity (pre or peri/postpubertal depending on the estimated years from peak height velocity). The adjusted models' coefficients were used to predict the effect of reallocating time proportionally across behaviors on the outcomes. Results: In prepubertal young pediatric cancer survivors, reallocating time to MVPA from LPA, SB, and sleep was significantly associated with higher aBMD at total body (B = 1.765, P = 0.005), total hip (B = 1.709, P = 0.003), and lumbar spine (B = 2.093, P = 0.001). In peri/postpubertal survivors, reallocating time to LPA from MVPA, SB, and sleep was significantly associated with higher aBMD at all sites (B = 2.090 to 2.609, P = 0.003 to 0.038). Reallocating time to SB from MVPA or LPA was significantly associated with lower aBMD atmost sites in prepubertal and peri/postpubertal survivors, respectively. Finally, reallocating time to sleep from MVPA, LPA, and SB was significantly associated with lower aBMD at total body (B = -2.572, P = 0.036) and total hip (B = -3.371, P = 0.015). Conclusions: These findings suggest that every move counts and underline the benefits of increasing MVPA or LPA, when low MVPA levels are present, for bone regeneration after pediatric cancer treatment completion. [ABSTRACT FROM AUTHOR]

Increasing step rate has been proposed to reduce overuse injury risk in runners by reducing the magnitude of musculoskeletal loading. Although estimating structure-specific loads is challenging, during level running, changes in a runner's vertical ground reaction force (vGRF) may provide insight to changes in their musculoskeletal loading. Further, vGRF can be approximated using force sensing insoles. Purpose: The primary goal of this study was to examine changes in peak insole force and cumulative weighted peak force (CWPF)/km with increased step rate in collegiate runners. The secondary goal was to determine whether sacral acceleration correlates with insole force when increasing step rate. Methods: Twelve collegiate distance runners ran 1000 m outdoors at 3.83 m⋅s-1 at preferred and 10% increased step rates while insole force and sacral acceleration were recorded. Cumulative weighted peak force/km was calculated from insole force based on cumulative damage models. The effects of step rate on peak insole force and CWPF⋅km-1 were tested using paired t tests or Wilcoxon tests. Correlation coefficients between peak axial (approximately vertical) sacral acceleration times body mass and peak insole force were calculated on cohort and individual levels. Results: Peak insole force and CWPF⋅km-1 decreased (P < 0.001) with increased step rate. Peak axial sacral acceleration did not correlate with peak insole force on the cohort level (r = 0.3 5, P = 0.109) but did within individuals (mean, r = 0.69-0.78; P < 0.05). Conclusions: Increasing step rate may reduce peak vGRF and CWPF⋅km-1 in collegiate runners. Therefore, clinicians should consider step rate interventions to reduce peak and cumulative vGRF in this population. Individual-specific calibrations may be required to assess changes in peak vGRF in response to increasing step rate using wearable accelerometers. [ABSTRACT FROM AUTHOR]

Purpose: Hip and knee arthroplasty aims to reduce joint pain and increase functional mobility in patients with osteoarthritis; however, the degree to which arthroplasty is associated with higher physical activity is unclear. The current study sought to assess the association of hip and knee arthroplasty with objectively measured physical activity. Methods: This cross-sectional study analyzed wrist-worn accelerometer data collected in 2013-2016 from UK Biobank participants (aged 43-78 yr). Multivariable linear regression was performed to assess step count, cadence, overall acceleration, and activity behaviors between nonarthritic controls, end-stage arthritic, and postoperative cohorts, controlling for demographic and behavioral confounders. From a cohort of 94,707 participants with valid accelerometer wear time and complete self-reported data, electronic health records were used to identify 3506 participants having undergone primary or revision hip or knee arthroplasty and 68,389 nonarthritic controls. Results: End-stage hip or knee arthritis was associated with taking 1129 fewer steps per day (95% confidence interval (CI), 811-1447; P < 0.001) and having 5.8 fewer minutes per day (95% CI, 3.0-8.7; P < 0.001) of moderate-to-vigorous activity compared with nonarthritic controls. Unilateral primary hip and knee arthroplasties were associated with 877 (95% CI, 284-1471; P = 0.004) and 893 (95% CI, 232-1554; P = 0.008) more steps than end-stage osteoarthritic participants, respectively. Postoperative unilateral hip arthroplasty participants demonstrated levels of moderate-to-vigorous physical activity and daily step count equivalent to nonarthritic controls. No difference in physical activity was observed between any cohorts in terms of overall acceleration, or time spent in daily light activity, sedentary behavior, or sleep. Conclusions: Hip and knee arthroplasties are associated with higher levels of physical activity compared with participants with end-stage arthritis. Unilateral hip arthroplasty patients, in particular, demonstrate equivalence to nonarthritic peers at more than 1 yr after surgery. [ABSTRACT FROM AUTHOR]

Purpose: Less physical activity has been associated with systemic biomarkers of cartilage breakdown after anterior cruciate ligament reconstruction (ACLR). However, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity after ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR. Methods: Daily steps and MVPA were assessed over 7 d using an accelerometer worn on the hip in 26 individuals between 6 and 12 months after primary unilateral ACLR. Resting T1rho MRI was collected bilaterally, and T1rho MRI interlimb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex. Results: Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA (R 2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior (P = 0.025), central (P = 0.002), and posterior (P = 0.002) medial femoral condyle. Conclusions: Lesser physical activity may be a risk factor for maintaining cartilage health after ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females. [ABSTRACT FROM AUTHOR]

Purpose: Accelerometer-assessed physical activity (PA) can be summarized using cut-point–free or population-specific cut-point–based outcomes. We aimed to 1) examine the interrelationship between cut-point–free (intensity gradient (IG) and average acceleration (AvAcc)) and cut-point–based accelerometer metrics, 2) compare the association between cardiorespiratory fitness (CRF) and cut-point–free metrics to that with cut-point–based metrics in healthy adults aged 20 to 89 yr and patients with heart failure, and 3) provide age-, sex-, and CRF-related reference values for healthy adults. Methods: In the COmPLETE study, 463 healthy adults and 67 patients with heart failure wore GENEActiv accelerometers on their nondominant wrist and underwent cardiopulmonary exercise testing. Cut-point–free (IG: distribution of intensity of activity across the day; AvAcc: proxy of volume of activity) and traditional (moderate-to-vigorous and vigorous activity) metrics were generated. The "interpretablePA" R-package was developed to translate findings into clinical practice. Results: IG and AvAcc yield complementary information on PA with both IG (P = 0.009) and AvAcc (P < 0.001) independently associated with CRF in healthy individuals (adjusted R 2 = 73.9%). Only IG was independently associated with CRF in patients with heart failure (P = 0.043, adjusted R 2 = 38.4%). The best cut-point–free and cut-point–based model had similar predictive value for CRF in both cohorts. We produced age- and sex-specific reference values and percentile curves for IG, AvAcc, moderate-to-vigorous PA, and vigorous PA for healthy adults. Conclusions: IG and AvAcc are strongly associated with CRF and thus indirectly with the risk of noncommunicable diseases and mortality, in healthy adults and patients with heart failure. However, unlike cut-point–based metrics, IG and AvAcc are comparable across populations. Our reference values provide a healthy age- and sex-specific comparison that may enhance the translation and utility of cut-point–free metrics in clinical practice. [ABSTRACT FROM AUTHOR]

Purpose: Accelerometers are used to objectively measure physical behaviors in free-living environments, typically for seven consecutive days or more. We examined whether participants experience "wear fatigue," a decline in wear time day over day, during typical assessment period acquired in a nationally representative sample of 6- to 80-yr-olds in the United States. Methods: Participants were instructed to wear an ActiGraph GT3X+ on their nondominant wrist continuously for seven consecutive days. Participants with seven complete days of recorded data, regardless of wear status, were included in the analyses (N = 13,649). Wear was scored with the sleep, wake, and nonwear algorithm. Results: Participants averaged 1248 ± 3.6 min·d−1 (mean ± SE) of wear over the assessment, but wear time linearly decreased from day 1 (1295 ± 3.2 min) to day 7 (1170 ± 5.3 min), resulting in a wear fatigue of −18.1 ± 0.7 min·d−1 (β ± SE). Wear fatigue did not differ by sex but varied by age-group—highest in adolescents (−26.8 ± 2.4 min·d−1) and lowest in older adults (−9.3 ± 0.9 min·d−1). Wear was lower in evening (1800–2359 h) and early morning (0000–0559 h) compared with the middle of the day and on weekend days compared with weekdays. We verified similar wear fatigue (−23.5 ± 0.7 min·d−1) in a separate sample (N = 14,631) with hip-worn devices and different wear scoring. Applying minimum wear criteria of ≥10 h·d−1 for ≥4 d reduced wear fatigue to −5.3 and −18.7 min·d−1 for the wrist and hip, respectively. Conclusions: Patterns of wear suggest noncompliance may disproportionately affect estimates of sleep and sedentary behavior, particularly for adolescents. Further study is needed to determine the effect of wear fatigue on longer assessments. [ABSTRACT FROM AUTHOR]

Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Chalkley, D, Cole, MH, Johnston, RD, and Cormack, SJ. Validity and reliability of thoracic-mounted inertial measurement units to derive gait characteristics during running. J Strength Cond Res 38(2): 274-282, 2024--Inertial measurement units (IMUs) attached to the tibia or lumbar spine can be used to analyze running gait but, with teamsports, are often contained in global navigation satellite system (GNSS) units worn on the thoracic spine. We assessed the validity and reliability of thoracic-mounted IMUs to derive gait characteristics, including peak vertical ground reaction force (vGRFpeak) and vertical stiffness (Kvert). Sixteen recreationally active subjects performed 40 m run throughs at 3-4, 5-6, and 7-8 m·s21. Inertial measurement units were attached to the tibia, lumbar, and thoracic spine, whereas 2 GNSS units were also worn on the thoracic spine. Initial contact (IC) from a validated algorithm was evaluated with F1 score and agreement (mean difference 6SD) of gait data with the tibia and lumbar spine using nonparametric limits of agreement (LoA). Test-retest error {coefficient of variation, CV (95% confidence interval [CI])} established reliability. Thoracic IMUs detected a nearly perfect proportion (F1 $ 0.95) of IC events compared with tibia and lumbar sites. Step length had the strongest agreement (0 6 0.04 m) at 3-4 m·s21, whereas contact time improved from 3 to 4 (20.02860.018 second) to 7-8m·s21 (20.00460.013 second). All values for Kvert fell within the LoA at 7-8 m·s21. Test-retest error was #12.8% for all gait characteristics obtained from GNSS units, where Kvert was most reliable at 3-4 m·s21 (6.8% [5.2, 9.6]) and vGRFpeak at 7-8m·s21 (3.7% [2.5, 5.2]). The thoracic-spine site is suitable to derive gait characteristics, including Kvert, from IMUs within GNSS units, eliminating the need for additional sensors to analyze running gait. [ABSTRACT FROM AUTHOR]

Brown, FSA, Fields, JB, Jagim, AR, Baker, RE, and Jones, MT. Analysis of in-season external load and sport performance in women's collegiate basketball. J Strength Cond Res 38(2): 318-324, 2024--Quantifying and monitoring athlete workload throughout a competitive season is a means to manage player readiness. Therefore, the purpose of the current study was to quantify practice and game external loads and to assess the relationship between such loads and basketball-specific performance metrics across a women's collegiate basketball season. Thirteen National Collegiate Athletic Association Division I women basketball athletes (age 20.08 6 1.55 years) wore Global Positioning Systems sensors equipped with triaxial accelerometers for 29 games and 66 practices during the 2019-20 season. A multivariate analysis of variance was used to assess differences in external load between high- and low-minute players and across quarters within games (p < 0.05). Bivariate Pearson correlation coefficients were run to determine relationships between external loads and metrics of basketball performance. Findings indicated that highand low-minute athletes experienced different loads during games and practices (p, 0.001). External loads differed by quarter, such that player load (PL) was highest in Q4 (p 5 0.007), PL·min21 was highest in Q1 and lowest in Q4 (p, 0.001), and explosive ratio (i.e., ratio of PL and explosive efforts) was lowest in Q3 (p50.45). Relationships existed between PL·min21 and field goals (r5 0.41; p50.02) and between the explosive ratio and free throws (r50.377 p50.04). These results can be used to inform design of training sessions with the intent to prepare athletes for the demands of the competitive season. It is recommended that future research continue to explore the relationship of sport-specific performance metrics and athlete external load. [ABSTRACT FROM AUTHOR]

Horsley, BJ, Tofari, PJ, Halson, SL, Kemp, JG, Johnston, RD, and Cormack, SJ. Thoracic-worn accelerometers detect fatiguerelated changes in vertical stiffness during sprinting. J Strength Cond Res 38(2): 283-289, 2024--Thoracic-mounted accelerometers are valid and reliable for analyzing gait characteristics and may provide the opportunity to assess running-related neuromuscular fatigue (NMF) during training and competition without the need for additional tests, such as a countermovement jump (CMJ). However, their sensitivity for detecting fatigue-related changes in gait across different speeds is unclear. We, therefore, assessed the changes in accelerometer-derived gait characteristics, including vertical stiffness (Kvert), following a repeated sprint protocol (RSP). Sixteen recreationally active subjects performed single and repeated CMJs on a force plate and 40 m run throughs overground at 3-4, 5-6, and 7-8 m·s21 pre-post a 123 40 mRSP. Gait characteristics (contact time, step frequency, step length, Kvert, etc.) were derived from an accelerometer contained within a global navigation satellite system unit on the thoracic spine using a validated algorithm. Changes in running gait and CMJ performance were assessed using a linear mixed-effects model (95% confidence interval [95% CI]; effect size [ES]). Significance was set at p < 0.05. A significant reduction in Kvert occurred at 7-8m·s21 following the RSP (28.51 kN·m21 [213.9, 23.11]; p 5 0.007; ES [95% CI] 5 20.39 [20.62, 20.15]) which coincided with a decreased jump height (20.03 m [20.04, 20.01]; p 5 0.002; ES [95% CI] 5 20.87 [21.41, 20.30]). However, all other gait characteristics were not significantly different irrespective of speed. Thoracic-worn accelerometers can detect changes in Kvert at 7-8 m·s21 which may be useful for monitoring NMF during sprinting. However, a RSP does not result in altered gait mechanics in subsequent running at lower speeds. [ABSTRACT FROM AUTHOR]

Heredia-Elvar, JR, Juan-Recio, C, Prat-Luri, A, Barbado, D, R'ıos-Calonge, Jdl, and Vera-Garcia, FJ. Exercise intensity progressions and criteria to prescribe core stability exercises in young physically active men: a smartphone accelerometer-based study. J Strength Cond Res 38(2): 266-273, 2024--The establishment of core stability (CS) exercise intensity progressions in sport and clinical settings is normally based on subjective criteria. Therefore, this study aimed to develop exercise intensity progressions for some of the most common CS exercises through smartphone accelerometry and to analyze the effect of the subjects' lumbopelvic postural control on these progressions. Fifty-seven healthy young physically active male students performed 7 isometric variations of front bridge, back bridge, side bridge, and bird-dog exercises with a smartphone accelerometer placed on the pelvis. Mean pelvic accelerations were calculated during each variation to evaluate the lumbopelvic postural control challenge imposed on the subjects as an index of exercise intensity of difficulty. For the bridge exercises, long bridging produced higher pelvic accelerations than short bridging, bridging with single-leg support was more intense than bridging with double-leg support (even with both legs on a hemisphere ball for the back and front bridge), and the most difficult variations were those performed on a Swiss ball, mainly the variations with single-leg support. For the bird-dog exercise, the 2-point positions weremore intense than the 3-point positions, the variations performed with a knee on the hemisphere ball produced higher pelvic accelerations than similar variations performed with the forearm on the hemisphere ball, and the variationswith limbmotions generated higher pelvic accelerations than similar variations performed without limbmotions. Although the CS exercise progressionswere very similar across subjects, our results showed the need to individualize the prescription of theCS exercise progressions based on the subjects' lumbopelvic postural control level. [ABSTRACT FROM AUTHOR]

Comparative Analysis of ActiGraph Step Counting Methods in Adults: A Systematic Literature Review and Meta-Analysis. Med. Sci. Sports Exerc., Vol. 56, No. 1, pp. 53-62, 2024. Purpose: The primary aim of this study was to compare steps per day across ActiGraph models, wear locations, and filtering methods. A secondary aim was to compare ActiGraph steps per day to those estimated by the ankle-worn StepWatch. Methods: We conducted a systematic literature review to identify studies of adults published before May 12, 2022, that compared free-living steps per day of ActiGraph step counting methods and studies that compared ActiGraph to StepWatch. Random-effects meta-analysis compared ActiGraph models, wear locations, filter mechanisms, and ActiGraph to StepWatch steps per day. A sensitivity analysis of wear location by younger and older age was included. Results: Twelve studies, with 46 comparisons, were identified.When worn on the hip, the AM-7164 recorded 123% of the GT series steps (no low-frequency extension (no LFE) or default filter). However, the AM-7164 recorded 72% of the GT series steps when the LFE was enabled. Independent of the filter used (i.e., LFE, no LFE), ActiGraph GT series monitors captured more steps on the wrist than on the hip, especially among older adults. Enabling the LFE on the GT series monitors consistently recorded more steps, regardless of wear location. When using the default filter (no LFE), ActiGraph recorded fewer steps than StepWatch (ActiGraph on hip 73% and ActiGraph on wrist 97% of StepWatch steps). When LFE was enabled, ActiGraph recorded more steps than StepWatch (ActiGraph on the hip, 132%; ActiGraph on the wrist, 178% of StepWatch steps). Conclusions: The choice of ActiGraph model, wear location, and filter all impacted steps per day in adults. These can markedly alter the steps recorded compared with a criterion method (StepWatch). This review provides critical insights for comparing studies using different ActiGraph step counting methods. [ABSTRACT FROM AUTHOR]

Purpose: Existing sedentary behavior interventions have largely achieved mixed results. Conventionally, interventions have attempted to reduce sedentary behavior using a full-day approach. An alternative strategymay be to target specific periods during the day and/orweek. This study examined the day-of-the-week (Monday to Sunday) and time-of-the-day patterns (3-and 6-h periods) of sedentary behavior among U.S. Hispanics/Latinos adults. Methods: Participants (n = 12,241) from the Hispanic Community Health Study/Study of Latinos, a multisite community-based prospective cohort study of Hispanic/Latino adults, were studied. Sedentary behavior was assessed for 1 wk using a hip-mounted accelerometer through total sedentary time, sedentary time in bouts ≥60 min, and total number of sedentary breaks. The temporal patterns of sedentary behavior metrics were evaluated using linear mixed effect models accounting for the Hispanic Community Health Study/Study of Latinos complex survey design.Results: Therewere statistically significant variations in temporal patterns across day-of-the-week and time-of-the-day periods for all three metrics (P < 0.001). Adults were more sedentary on weekends than on weekdays and most sedentary on Sundays. The time-of-the-day patterns had a U-curve pattern wherein adults weremost sedentary late at night, became less sedentary throughout the day, reached peak activeness around noon, then gradually became more sedentary into the evening. These patterns were largely robust across seasonality and most sociodemographic characteristics, including age, employment status, work shift schedule, acculturation, and field center. Conclusions: Our findings suggest that early mornings, evenings, and weekends were the more sedentary periods in this cohort of Hispanic/Latino adults, characterized by higher volumes of sedentary time, higher volumes of time in prolonged sedentary bouts, and fewer number of sedentary breaks than other time periods, highlighting important windows of opportunity to reduce sedentary behavior. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study is to evaluate the feasibility of a workplace intervention supporting employees to interrupt sitting time with short bouts of activity (termed an opportunity to move [OTM]). Methods: Using an interrupted time series design, 58 sedentary employees provided baseline assessments of physical activity, health, and work-related outcomes and completed the 12-week intervention. Assessments were repeated immediately and 12 weeks after intervention. Focus groups explored intervention acceptability. Results: Accelerometer data showed no change in the number of OTMs taken before to after intervention, while participants self-reported 62-69% intervention adherence. Physical activity at work, productivity, and musculoskeletal health improved but cardiometabolic health and psychological well-being did not. Intervention components were viewed favorably (pending amendments), but taking an OTM every 30 minutes was not feasible. [ABSTRACT FROM AUTHOR]

Background: Physical activity is necessary for improved health outcomes among older adults with coronary artery disease (CAD), and device-based assessment of physical activity is preferred for accurate measurement. Many previous studies have applied accelerometry to examine physical activity in this population, but no reviews have systematically examined the application of various accelerometers tomeasure physical activity in older adults with CAD. Objective: This integrative review aimed to examine accelerometry application to measure physical activity in older adults with CAD and provide guidance for accelerometer selection and settings. Methods: Six databases--CINAHL, PubMed, PsycINFO, Scopus, EMBASE, andGoogle Scholar--were searched for information sources. Authors of selected studies applied accelerometers to measure physical activity and included adults 60 years or older with CAD. Results: Among 12 studies reviewed, 5 were randomized controlled trials, and most used an age cutoff of 65 years for older adults. The most frequently used accelerometer was the RT3, and the most common device placement was the waist/hip. Data collection duration was typically 3 consecutive days. However, many study authors did not report epoch length, sampling frequency, number of valid hours of data required per day, total number of valid days of data needed, or criteria for nonwear time. Conclusions: On the basis of data synthesis and previous study results, triaxial research-grade accelerometers, waist/hip placement, and a 5- to 7-day monitoring period are recommended for measuring physical activity in older adultswith CAD. However, the study purpose, device and participant characteristics, and physical activity outcomes of interest should be considered during device selection. [ABSTRACT FROM AUTHOR]

Purpose: This study examined the associations of motor proficiency with moderate-to-vigorous physical activity (MVPA) and sleep quality in children with attention-deficit/hyperactivity disorder (ADHD) and children with typical development (TD). Methods: This cross-sectional study included 88medical-naive children with ADHD age 6-12 yr (mean (SD) age, 8.43 (1.38) yr; 81.8% boys) and 40 age-matched children with TD (mean (SD) age, 8.46 (1.44) yr; 60% boys). MVPA was recorded by a wGT3X-BT accelerometer for 7 consecutive days. Motor proficiency was assessed using the Test of Gross Motor Development--Third Edition. Sleep quality was assessed using a self-report questionnaire. Results: ChildrenwithADHDspent significantly less time inMVPAdaily, displayed less proficiency in locomotor and ball skills, and reported poorer sleep quality (e.g., longer sleep latency, less sleep duration, and lower sleep efficiency) than children with TD. MVPA guideline attainment and sleep duration significantly predicted locomotor skills development; in turn, locomotor skills predictedMVPA guideline attainment.MVPA and ball skills increased by age in children with ADHD. Conclusions: Our results highlight the importance of promoting MVPA, motor proficiency, and sleep duration in children with ADHD and TD since childhood. [ABSTRACT FROM AUTHOR]

Five times sit-to-stand (STS) test is commonly used as a clinical assessment of lower-extremity functional ability, but its association with free-living performance has not been studied. Therefore, we investigated the association between laboratory-based STS capacity and free-living STS performance using accelerometry. The results were stratified according to age and functional ability groups. Methods: This cross-sectional study included 497 participants (63% women) 60-90 yr old from three independent studies. A thigh-worn triaxial accelerometer was used to estimate angular velocity in maximal laboratory-based STS capacity and in free-living STS transitions over 3-7 d of continuous monitoring. Functional ability was assessed with short physical performance battery. Results: Laboratory-based STS capacity was moderately associated with the free-living mean and maximal STS performance (r = 0.52-0.65, P < 0.01). Angular velocity was lower in older compared with younger and in low- versus high-functioning groups, in both capacity and free-living STS variables (all P < 0.05). Overall, angular velocity was higher in capacity compared with free-living STS performance. The STS reserve (test capacity - free-living maximal performance) was larger in younger and in high-functioning groups compared with older and low-functioning groups (all P < 0.05). Conclusions: Laboratory-based STS capacity and free-living performance were found to be associated. However, capacity and performance are not interchangeable but rather provide complementary information. Older and low-functioning individuals seemed to perform free-living STS movements at a higher percentage of their maximal capacity compared with younger and high-functioning individuals. Therefore, we postulate that low capacity may limit free-living performance. [ABSTRACT FROM AUTHOR]

The present study was intended to i) investigate the relationship between metabolic power average (MPA), acceleration (AcZ) and deceleration (DcZ) zones, and their differences (Δ) on 3 load levels with noncontact injuries in professional players throughout a full soccer season and ii) to analyze the injury risk associated between high-load versus low-load levels for each of the aforementioned parameters with odds ratios (OR) and relative risk (RR), respectively. Twenty-one professional soccer players (age = 28.3 ± 3.9 years) were monitored during a full season (48 weeks) through global positioning system (GPS). A relationship between MPA and accelerometer-based GPS, mainly in explosive actions (i.e., AcZs and DcZs), was found. A higher incidence of injuries in the high-load weeks compared with the low-load weeks were reported (mainly in MPA, AcZ1, AcZ2, and DcZ3 variables). Moreover, significant means of OR (mean = 4.3) and RR (mean = 2.6) of noncontact injuries were established in intense periods with higher metabolic load (i.e., power accelerations, AcZ1, x² = 0.022). Our results may be useful for coaches, sports scientists, and researchers regarding the optimization of the athletes' performance, as well as providing insights about the impact of intense exercise. [ABSTRACT FROM AUTHOR]

Purpose: In a cross-sectional sample of US Hispanic/Latino adults, we aimed to describe step-based metric distributions, estimate their associations with activity counts and self-report, and calibrate step-based translations of current (2018) US physical activity (PA) guidelines, that is, ≥150 min·wk-1 moderate-to-vigorous PA (MVPA) from accelerometer counts and self-report. Methods: The Hispanic Community Health Study/Study of Latinos enrolled 16,415 Hispanic/Latino adults 18-74 yr from four US cities (2008-2011). Participants completed the Global PA Questionnaire and 1 wk of Actical accelerometer wear (n = 12,528). Weighted medians were used to describe step-based metrics, and Spearman correlations estimated their relationships with count-based and self-reported PA indicators. Receiver operator characteristic curve analyses were used to examine the ability of each step-basedmetric to classify participantsmeeting PAguidelines. Results: Overall, US Hispanic/Latino adults accumulated medians of 6770 steps per day and 6, 18, 236, and 630 min·d-1 at ≥100, ≥70, 1-69, and 0 steps perminute, respectively. Count-based time inMVPA, light PA, and sedentary behavior weremost strongly correlated (rs = 0.79-0.85) with times ≥70, 1-69, and 0 steps perminute, respectively,whereas self-reported MVPA had similar correlations with steps per day and times ≥40 and ≥70 steps per minute (rs = 0.28-0.29). Time ≥70 steps per minute had the greatest capacity to classify participants meeting PA guidelines with both measures of MVPA. Conclusions: This study provides the first normative values (based on percentiles) of step-based metrics for US Hispanic/Latino adults, which can facilitate surveillance, program planning, research, and data interpretation. Our finding that PA guidelines corresponded to 6000-7000 steps per day or ~20 min·d-1 at ≥70 steps per minute with an Actical accelerometer can be considered alongside dose-response relationships with health outcomes to develop step-based recommendations that are consistent with and better communicate PA guidelines. [ABSTRACT FROM AUTHOR]

Purpose: Assessment of trends in physical activity (PA) and sedentary time (ST) is important for evaluating the effectiveness of national policies and setting goals to improve population PA. This study describes changes in measured PA and ST through motion sensors of the Portuguese population from 2008 to 2018. Methods: PA and ST were measured with accelerometry from individuals (≥10 yr) participating in the 2008 (n = 4 532) and 2018 (n = 6 369) Portuguese PA Surveillance Systems. Changes were analyzed using generalized linear and logistic models adjusted for accelerometer wear time. A weight factor was applied to all analyses in order to achieve national representativeness of the present results. Results: In 2018, 15.4%, 71.2%, and 30.6% of Portuguese youth, adults, and older adults met the PA recommendations. Compared with 2008, the percentage meeting the PA guidelines increased in youth females (4.7% vs 7.7%, P < 0.05) and adult males (72.2% vs 79.4%, P < 0.05). A decrease in ST was observed for adult males, whereas ST increased in all youth. Male youth decreased the number of breaks in ST (BST per hour), whereas a favorable increase was found for both adult and older adult males and females. Conclusions: PA has remained fairly stable between 2008 and 2018 for all groups, except for youth females and adult males. For ST, a favorable decrease was observed for adult males; however, an inverse trend was found in youth. These results are relevant for policy makers to develop health care policies aimed at promoting PAand reducing ST across all age-groups. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the criterion validity of Activities Completed over Time (ACT24), an automated previous-day recall tool designed for mobile devices for 1) estimating sedentary versus active time compared with an activPAL, and 2) estimating time spent in activity domains (e.g., work, household, leisure) compared with direct observation (DO). Methods: Over a 7-d study period, 53 participants were sent invitations to complete three automated ACT24 recalls and to wear an activPAL device. A subset (N = 24) consented to two, 3-h video-recorded DO sessions. activPAL and ACT24 data were matched by date, and agreement for sedentary versus active time was compared between methods using paired t -tests for mean differences and spearman correlations. We compared DO and ACT24 results by domain for overall time use and separately for sedentary and active time using κ statistics and tested mean differences with linear mixed models. Results: Compared with the activPAL, the mean difference in ACT24 sedentary time was 1.9% (mean (95% confidence interval), −0.17 (−0.75 to 0.40) h·d−1), and the mean difference for ACT24 active time was 2.2% (0.14 (−0.32 to 0.60) h·d−1). Correlations were R = 0.61 (95% confidence interval, 0.39 to 0.76) and R = 0.65 (0.44 to0.78) for sedentary and active time, respectively. Domain-specific agreement was substantial for leisure-time, work, and shopping/errands (κ range, 0.63–0.79), moderate for transportation (κ = 0.49), and fair for personal care and household activities (κ = 0.24 and 0.33). ACT24 estimates of average time within each domain were not significantly different from DO. Conclusions: The present study confirms that ACT24 is accurate for group-level estimation of active and sedentary time. Domain-specific agreement tended to be higher for more commonly reported activities and those that were of longer duration. [ABSTRACT FROM AUTHOR]

The NFPA's Wellness Fitness Initiative needs to emphasize a PA recommendation to increase cardiorespiratory fitness (CRF) and overall health. Adequate or increased amounts of PA could be beneficial for firefighters' CRF as it lowers the cardiovascular workload to perform firefighter tasks, thus, improving job efficiency. Objective: The aim of the study is to objectively assess if firefighters are meeting the National Fire Protection Association (NFPA) cardiorespiratory fitness (CRF) and American College of Sports Medicine/American Heart Association physical activity (PA) guidelines. Methods: Two independent fire departments from the Midwest participated in the study. Firefighters wore an accelerometer to track PA and associated intensities. In addition, firefighters completed a stage-graded exercise test TO determine their maximal oxygen uptake (V˙O2max). Results: A total of 43 career firefighters completed the study (fire department 1 [FD1]: n = 29, FD2: n = 14). Almost half (44.8% FD1 and 42.9% FD2) met the NFPA CRF guidelines. Compared with the American College of Sports Medicine PA Guidelines of 30 min/d of moderate-to-vigorous PA, more than half of FD2 (57.1%) met the recommended amount of PA, whereas FD1 had less than half (48.3%). Conclusions: These data demonstrate the need to improve firefighters' PA levels, CRF, and overall health. [ABSTRACT FROM AUTHOR]

This study determined stroke and movement accelerometry metrics from a wearable sensor and compared between court surface (grass vs. hard) and match outcome (win vs. loss) during competitive tennis match-play. Eight junior high-performance tennis players wore a trunk-mounted global positioning system, with in-built accelerometer, magnetometer, and gyroscope during singles matches on hard and grass courts. The manufacturer software calculated accelerometer-derived total player load (tPL). A prototype algorithm classified forehands, backhands, serves, and "other" strokes, thereby calculating stroke PL (sPL) from individual strokes. Movement PL (mPL) was calculated as the difference between tPL and sPL, with all metrics reported as absolute and relative (min-1, %, and ·stroke). Analysis of accelerometer load and stroke count metrics was performed through a two-way (surface [grass vs. hard] × match outcome [win vs. loss]) analysis of variance (p < 0.05) and effect sizes (Cohen's d). No interaction effects for surface and match outcome existed for absolute tPL, mPL, and sPL (p > 0.05). Increased mPL% featured on grass courts, whereas sPL% was increased on hard courts (p = 0.04, d = 1.18[0.31-2.02]). Elevated sPL·min-1 existed on hard courts (p = 0.04, d = 1.19[0.32-2.04]), but no differences in tPL·min-1 and mPL·min-1 were evident for surface or outcome (p > 0.05). Relative forehand sPL (FH-sPL·min-1) was higher on hard courts (p = 0.03, d = 1.18[0.31-2.02]) alongside higher forehand counts (p = 0.01, d = 1.29[0.40-2.14]). Hitting demands are heightened on hard courts from increased sPL and counts. Conversely, increased mPL% on grass courts likely reflects the specific movement demands from point-play. Physical preparation strategies during training blocks can be tailored toward movement or hitting loads to suit competitive surfaces. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to assess whether total daily physical activity (PA), PA intensities, sedentary time (ST), and prolonged ST are associated with differences in the gut microbiota composition or short-chain fatty acid (SCFA) profile of adults with overweight or obesity. Methods: Cross-sectional associations between total daily PA (counts per minute), PA intensities (light and moderate-to-vigorous (MVPA)), ST, prolonged ST, and fecal microbiota composition were assessed in adults (n = 124) between 25 and 45 yr of age with body mass index ≥25 kg·m−2. Fecal microbiota composition was assessed with 16S rRNA gene sequencing. Daily PA and ST were measured with a hip-worn ActiGraph wGT3X-BT accelerometer. Results: Daily PA volume and intensity were positively associated with relative abundance of Faecalibacterium (P = 0.04) and negatively associated with the abundances of Alistipes , Parabacteroides , and Gemmiger (P = 0.003–0.04) as well as the concentrations of acetate, butyrate, and total SCFA (all P = 0.04). Conversely, ST was negatively associated with abundance of Faecalibacterium but positively associated with the abundances of taxa, including Ruminococcaceae, Parabacteroides , Alistipes , and Gemmiger. Clustering of participants based on whether they met PA recommendations suggested that SCFA profiles differed between individuals who did and did not meet PA recommendations. K-means clustering based on percent of time spent in MVPA and ST also identified differences in fecal microbiota composition between cluster 1 (lower MVPA, higher ST) and cluster 2 (higher MVPA, lower ST), including a higher abundance of Alistipes in cluster 1. Conclusions: The current analysis suggests a beneficial association of daily PA on the fecal microbiota and a negative association of ST, particularly with respect to the associations of these variables with the genera Faecalibacterium , a butyrate-producing taxon. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Applying extensive physical activity measurements, results suggest inverse dose–response relationship between physical activity and chronic pain, with stronger associations for those with more severe pain. Epidemiological literature on the relationship between physical activity and chronic pain is scarce and inconsistent. Hence, our aim was to assess the relationship applying comprehensive methodology, including self-reported and accelerometer measures of physical activity and different severity levels of chronic pain. We used data from the Tromsø Study (2015-2016). All residents in the municipality, aged 40 years and older were invited to participate (n = 32,591, 51% women). A total of 21,083 (53%) women reported on questionnaires. Additionally, 6778 participants (54% women) were invited to wear accelerometers (6125 with complete measurements). Our exposure measures were self-reported leisure time physical activity, exercise frequency, duration, and intensity and 2 accelerometer measures (steps per day and minutes of moderate to vigorous physical activity per day). Outcome measurements were chronic pain and moderate-to-severe chronic pain. We used Poisson regression to estimate chronic pain prevalence and prevalence ratios for each physical activity measure, with adjustments for sex, age, education level, smoking history, and occupational physical activity. Our main analyses showed an inverse dose–response relationship between all physical activity measures and both severity measures of chronic pain, except that the dose–response relationship with exercise duration was only found for moderate-to-severe pain. All findings were stronger for the moderate-to-severe pain outcomes than for chronic pain. Robustness analyses gave similar results as the main analyses. We conclude that an inverse dose-response association between physical activity and chronic pain is consistent across measures. To summarize, higher levels of physical activity is associated with less chronic pain and moderate-to-severe chronic pain. [ABSTRACT FROM AUTHOR]

Introduction: To establish a possible effect of Lycra sleeves, accurate recording of wear time is critical. The aim of this study was to test whether an accelerometer-embedded Lycra sleeve can measure wear compliance and record upper-limb (UL) movements/activity in people with stroke. Methods: Seven adults with stroke resulting in unilateral UL weakness were approached for participation in this study as a convenience sample, and five participants were recruited. Participants wore accelerometer-embedded Lycra sleeve on their affected arm for 8 to 10 hrs/d for 14 days and were prescribed four simple UL exercises. They completed a diary to record daily sleeve wear time and exercise times. Upper-limb function, shoulder muscle strength, range of movement, and pain were assessed at days 1 and 14. Results: Seven participants were approached, and five participants (72 ± 10 years) were recruited. The mean time since stroke was 20 months. Using an acceleration movement threshold of 0.01 g (g = acceleration of gravity) and the constructed algorithm, the sleeve donning and doffing time was identified. The mean accelerometer and diary-recorded wear time were 11.64 hrs/d (SD, 2.64) and 11.27 hrs/d (SD, 2.03), respectively. Individual spikes above threshold indicated UL activity but could not distinguish participant-recorded exercises from daily UL use. Arm function showed improvement in three of five participants. Conclusions: Accelerometers provide a practical method to record wear time of a Lycra sleeve, overcoming the necessity for patients to keep diaries, which can often be unreliable. A more sensitive accelerometer that can detect the direction of the acceleration and movement should be considered in future studies. Clinical Relevance: Accelerometers provide accurate data on Lycra sleeve wear time and may help with monitoring adherence. [ABSTRACT FROM AUTHOR]

Purpose: Chronic exposure to hypoxia can induce muscle wasting in unaccustomed individuals. Detailed assessment of the effects of hypoxia on muscle tissue adaptation in elite mountaineers has not been performed. This study aims to assess muscle volume after exposure to normobaric hypoxia. Methods: Two professional mountaineers (A and B) participated in a 35-d intervention of graded normobaric hypoxia with the aim of 14 d exposure to 8% oxygen corresponding to 7112-m altitude. Volume of the shank, thigh, and hip muscles was assessed by magnetic resonance imaging pre- and postintervention. Dietary intake and physical activity were monitored throughout the study from food images and accelerometry analysis, together with blood analysis and anthropometric measurements. Results: Hypoxia reduced total leg muscle volume by 3.3% ± 6.0% in A and by 9.4% ± 7.3% in B. A lost 288 g and B 642 g of muscle mass, whereas dietary intake only declined by ~23% in the last intervention week. Arterial oxygen saturation declined from 95% and 86% to 77% and 72% in A and B, respectively. In hypoxia, participants could not maintain their physical activity levels. Notably, muscle loss varied substantially across muscle groups amounting to 5.4% ± 3.0%, 8.3% ± 5.2%, and 4.1% ± 8.6% for hip, thigh, and shank muscles, respectively. Conclusions: Our results indicate that hypoxia and resultant reductions in physical activity and caloric intake lead to substantial loss of muscle mass that was accentuated in proximal muscle as opposed to distal muscles. Surprisingly, thigh muscle wasting during this intervention is comparable with that observed during strict 56-d bed rest. [ABSTRACT FROM AUTHOR]

There is a culture among rock climbers of striving to maintain low body mass and percentage body fat to enhance performance. Diet practices based on this belief might lead to increased risk of low energy availability (LEA) or eating disorders (EDs). Twenty-five advanced or elite rock climbers (male, n = 14; female, n = 11) had body composition measured, completed 4-day food intake and physical activity diaries while wearing an accelerometer and heart rate monitor, and completed the Eating Attitudes Test (EAT)-26 and the Low Energy Availability in Females Questionnaire (LEAF-Q; n = 11 female subjects only). EAT-26 scores of 3.5 (1.8, 7.0) [median (IQR)] and 9.3 ± 6.4 (mean ± SD) for male and female subjects, respectively, indicated low risk of ED in this cohort, but 4 female subjects were at high risk of LEA according to LEAF-Q scores. Suboptimal (<45 kcal·kg·FFM-1·d-1) and LEA (<30 kcal·kg·FFM-1·d-1) were evident in 88 and 28%, respectively, of climbers. However, only the female climbers had energy intakes (1775 ± 351 kcal·d-1) significantly lower than their calculated energy requirements (2056 ± 254 kcal·d-1; p = 0.006). In all subjects, carbohydrate intakes were lower (male subjects: 3.8 ± 1.2 g·kg-1·d-1, p = 0.002; female subjects: 3.4 ± 0.7 g·kg-1·d-1, p < 0.001), and fat intakes were higher (male subjects: 1.6 ± 0.5 g·kg-1·d-1, p < 0.001; female subjects: 1.4 ± 0.4 g·kg-1·day-1, p < 0.001) than current sports nutrition recommendations, and inadequate intakes of calcium, magnesium, and vitamin D were observed. Female subjects specifically had lower than recommended intakes of protein and iron. These results show that advanced and elite rock climbers have a high prevalence of LEA and have a risk of having nutritional deficiencies as result of their diet. [ABSTRACT FROM AUTHOR]

This study compared the movement- and stroke-related accelerometer profiles and stroke counts between common on-court tennis training drills. Ten, junior-elite, male tennis players wore a cervical-mounted global positioning systems, with in-built accelerometer, gyroscope, and magnetometer during hard court training sessions (n = 189). Individual training drills were classified into 8 categories based on previous research descriptions. Manufacturer software calculated total player load (tPL), while a prototype algorithm detected forehand (FH), backhands (BH), and serves and then calculated a stroke player load (sPL) from individual strokes. Movement player load (mPL) was calculated as the difference between tPL and sPL. Drill categories were compared for relative (.min-1) tPL, sPL, mPL, and stroke counts via a 1-way analysis of variance with effect sizes (Cohen's d) and 95% confidence intervals. Highest tPL.min-1 existed in accuracy and recovery or defensive drills (p < 0.05), with lowest tPL·min-1 values observed in match-play simulation (p < 0.05). For sPL·min-1, accuracy drills elicited greater values compared with all other drill types (p < 0.05), partly via greater FH-sPL·min-1 (p < 0.05), with lowest sPL·min-1 existing for match-play (p < 0.05). Accuracy, open, and recovery or defensive drills result in greater BH-sPL·min-1 and BH.min-1 (p < 0.05). Serve-sPL·min-1 is highest in technical and match-play drills (p < 0.05). Higher mPL·min-1 existed in accuracy, recovery or defensive, 2v1 net, open, and 2v1 baseline (p < 0.05). Furthermore, mPL·min-1 in points drills was greater than technical and match-play simulation drills (p < 0.05). Higher hitting-based accelerometer loads (sPL·min-1) exist in accuracy drills, whereas technical and match-play drills show the lowest movement demands (mPL·min-1). These findings can aid individual drill prescription for targeting movement or hitting load. [ABSTRACT FROM AUTHOR]

Background: Understanding the mechanism of interventions that increase physical activity (PA) is critical to developing robust intervention strategies. Aims: This study aims to examine the mediation effects of hypothesized changes in self-efficacy, social support, and barriers on daily changes in accelerometer-measured steps and the duration of moderate to vigorous PA over 3-month intervention and 6-month maintenance periods with a mobile phone–based PA education program. Methods: Data were analyzed for a total of 210 physically inactive women who were randomized. The mean (SD) age was 52.4 (11.0) years. The framework of Baron and Kenny and the Sobel test were used to evaluate the proportion of the treatment effect explained by mediation factors. Results: Postintervention PA changes were mediated by a reduction in self-efficacy and barriers and an increase in social support from friends during the intervention and maintenance periods (P ≤.05). However, social support from family was significant only during the intervention, but not the maintenance (P =.90). Barriers to PA had the largest mediation effect on the intervention, explaining 13% to 16% of the 3-month intervention effect and 14% to 19% of the 6-month maintenance effect on daily steps and duration of moderate to vigorous PA minutes (P ≤.05). Conclusions: Incorporating strategies for overcoming PA barriers and promoting social support for PA is important for the design of interventions for physically inactive women. However, a reduction in self-efficacy was observed in the intervention group at 3 and 9 months as compared with the control group. This unexpected finding requires further investigation. [ABSTRACT FROM AUTHOR]

Background: Low moderate-to-vigorous physical activity (MVPA) levels and obesity are associated with increased cardiometabolic disease risk. Objective: The aim of this study was to describe MVPA and cardiometabolic risk characteristics of insufficiently active African American women with obesity (N = 60) enrolled in a culturally tailored MVPA intervention. Methods: We assessed accelerometer-measured and self-reported MVPA, blood pressure, serum lipid profiles, cardiorespiratory fitness (VO2 peak), and aortic pulse wave velocity. Results: Participants (mean age, 38.4; mean body mass index, 40.6 kg/m2) averaged 15 min/d of accelerometer-measured MVPA and 30 min/wk of self-reported MVPA. Systolic and diastolic blood pressure levels were elevated (135.4 and 84.0 mm Hg, respectively). With the exception of low-density lipoprotein cholesterol (121.4 mg/dL) and high-density lipoprotein cholesterol (47.6 mg/dL), lipid profiles were within reference ranges. Compared with normative reference values, average VO2 peak was low (18.7 mL/kg/min), and pulse wave velocity was high (7.4 m/s). Conclusions: Our sample of insufficiently active African American women with obesity was at an elevated risk for cardiometabolic disease. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Physical activity may influence chronic disease risk, in part, through epigenetic mechanisms. Previous studies have demonstrated that an acute bout of physical activity can influence DNA methylation status. Few studies have explored the relationship between habitual, accelerometer-measured physical activity or sedentary time with epigenetic markers of aging. Methods: We used linear regression to examine cross-sectional associations of accelerometer-measured physical activity and sedentary time with extrinsic and intrinsic epigenetic age acceleration (EEAA and IEAA) models and GrimAge measured from blood samples from Framingham Heart Study participants with accelerometry and DNA methylation data (n = 2435; mean age, 54.9 ± 14.3; 46.0% men). Residuals of Hannum-, Horvath-, and GrimAge-predicted epigenetic age were calculated by regressing epigenetic age on chronological age. We took into account blood cell composition for EEAA, IEAA, and AdjGrimAge. Moderate to vigorous physical activity was log-transformed to normalize its distribution. Adjustment models accounted for family structure, age, sex, smoking status, cohort–laboratory indicator, and accelerometer wear time. We additionally explored adjustment for body mass index (BMI). Results: Walking 1500 more steps per day or spending 3 fewer hours sedentary was associated with >10 months lower GrimAge biological age (or ~1 month lower AdjGrimAge, after adjusting for blood cells, P < 0.05). Every 5 min·d−1 more moderate to vigorous physical activity was associated with 19–79 d of lower GrimAge (4–23 d lower using EEAA or AdjGrimAge, P < 0.01). Adjusting for BMI attenuated these results, but all statistically significant associations with AdjGrimAge remained. Conclusions: Greater habitual physical activity and lower sedentary time were associated with lower epigenetic age, which was partially explained by BMI. Further research should explore whether changes in physical activity influence methylation status and whether those modifications influence chronic disease risk. [ABSTRACT FROM AUTHOR]

Purpose: Physical activity (PA), sedentary time (SED), and energy intake (EI) are associated with fat mass accrual in children and youth. Previous studies relied primarily on cross-sectional designs and proxy measures of body composition such as body mass index. We aimed to prospectively investigate associations between PA, SED, EI, and total body fat mass accrual using dual-energy x-ray absorptiometry. Methods: This analysis of the mixed longitudinal Healthy Bones III Study included data from 312 participants (138 boys age 9 to 21 yr at baseline). For each participant, we acquired a maximum of four annual total body dual-energy x-ray absorptiometry scans from which we determined fat mass (in kilograms; n = 748 observations). We assessed total PA, moderate-to-vigorous PA (MVPA) and SED with accelerometers (ActiGraph GT1M) and measured EI via 24-h dietary recall. We fit sex-specific multilevel models adjusting for maturity (years from age at peak height velocity (APHV)), weight status, ethnicity, total PA, MVPA, SED, and EI. Results: Boys and girls demonstrated divergent trajectories of fat mass accrual; rate of fat mass accrual in girls was four times greater than boys at APHV and increased across adolescence, whereas boys' fat mass plateaued after APHV. In boys, within-person change in MVPA negatively predicted fat mass independent of SED; each annual increase in MVPA of 6 min·d−1 was associated with a 0.21-kg lower fat mass. In girls, between-person average MVPA negatively predicted fat mass accrual independent of SED; greater MVPA of 4 min·d−1 across adolescence was associated with a 0.31-kg lower fat mass. Conclusions: MVPA demonstrates an independent and negative effect on fat mass in boys and girls. Given different trajectories of fat mass accrual and movement behaviors between boys and girls, PA interventions aimed at preventing obesity in youth may benefit from a sex and gendered approach. [ABSTRACT FROM AUTHOR]

This study's aim was to investigate the validity, within-brand interunit reliability, and between-brand agreement of movement indicators from 3 commonly used global positioning system (GPS) units used in applied and research settings. Forty-two units (GPSports EVO; 10 Hz, n = 13: GPSports HPU; 5 Hz, n = 14: and Catapult S5; 10 Hz, n = 15) were investigated across 3 experiments: a 40-m linear track with all units pushed on a trolley, a sport simulation circuit with all units pulled on a sled, and a similar circuit with 3 models of units placed in a modified GPS vest worn by an athlete between the scapulae. Distance, speed, and acceleration indices were obtained and analyzed with the level of significance set (p < 0.05). The results demonstrated good to moderate (% mean difference; 0-6.5%) validity with criterion and good (coefficient of variation [CV] ± 90% confidence interval [CI]: 0-3.9%) interunit reliability for distance and speed in units. Ten hertz units demonstrated good to moderate (CV ± 90% CI: 0.21-5.58%) interunit reliability in all acceleration and deceleration measures, with 5 Hz units having good to poor (CV ± 90% CI: 4.54-12.78%) results. Agreement ranged from good to moderate (% mean difference; 0.01-7.8%) for distance, speed, and absolute acceleration/deceleration. Agreement ranged from good to poor (% mean difference; 2.21-32.74%) in average acceleration. The GPS units investigated can be compared within and between applied and research settings for distance and speed. However, caution is warranted in acceleration indices. This highlights the importance of testing other commonly used GPS models and brands. [ABSTRACT FROM AUTHOR]

Physical activity (PA) volume, intensity, and qualitative contextual information regarding activity type and loads carried are limited during U.S. Army Basic Combat Training (BCT). The purpose of this study was to characterize daily (05:00-20:00 hours) PA during BCT using a comprehensive approach. During 2 10-week BCT cycles (n = 40 trainees per cycle), pedometers, accelerometers, and direct observation were used to estimate daily step count, PA volume, and intensity. Physical activity intensity was categorized by metabolic equivalents (METs) such as "sedentary" (1-2 METs), "light" (2-3 METs), "moderate" (3-6 METs), or "vigorous" (≥6 METs). Daily PA data were analyzed longitudinally using linear mixed models, with significance set at p ≤ 0.05. The mean daily step count was 13,459 ± 4,376 steps, and the mean daily accelerometer-assessed PA volume and intensity were as follows: sedentary: 505 ± 98 minutes, light: 190 ± 78 minutes, moderate: 168 ± 51 minutes, and vigorous: 14 ± 14 minutes, with no differences between cycles for all measures (p > 0.50). Cumulative time on feet (~50%) and sitting (20-25%) accounted for most daily activity types during both cycles. Trainees, on average, carried between 3 and 9 kg, and ≥9 kg, for 60% and 10% of the monitored day, respectively. Basic Combat Training's physical demands are high, where trainees achieved 1.7 to 2.7 times greater daily ambulation and 6 times the recommended weekly moderate-to-vigorous PA compared with civilian counterparts and performed weight-bearing load carriage for nearly half of the day. Basic Combat Training-associated PA may increase injury risk among trainees unaccustomed to arduous PA and exercise. Implementing national PA policies to improve physical fitness and facilitate acclimatization to BCT's high physical demands could reduce public health burdens and military nonreadiness. [ABSTRACT FROM AUTHOR]

Commercially available player tracking sensors such as the Polar Team Pro system (PTPS) have been used to monitor athlete performance. Use during ice hockey practices and games has resulted in seemingly plausible and valid values for internal metrics (heart rate); however, external metrics (distance, speed, and acceleration) seem sporadic and counterintuitive. To determine the validity of the PTPS for measuring sprint speed with collegiate hockey players, 15 NCAA Division I male athletes (21.86 ± 1.04 years, 175.86 ± 6.78 cm, 80.58 ± 4.44 kg) participated in the study. Subjects wore a PTPS strap, at the level of the xiphoid process, and performed 2 sprints of 15.24 m (blue line to blue line) and 35.05 m (red line to the far blue line) in 3 conditions: indoor ice skating, indoor running, and outdoor running. Timing gates (TG) were used to determine sprint times, which allowed for manual calculation of speed. Speed values from the PTPS and TG were compared using paired-samples t-tests, and an alpha level of 0.05, 2-sided, was set a priori as a significance level. For indoor ice skating, PTPS significantly underestimated speeds at both distances (p < 0.001). However, PTPS significantly overestimated speeds for indoor and outdoor sprints at both distances (p ≤ 0.001). The PTPS is not accurate for measuring short-distance linear sprint speed or linear sprint speed during indoor ice skating. The inconsistency in speed values needs to be taken into consideration when using the system for science-based training because inaccurate speed values may negatively affect other external performance metrics provided by PTPS. [ABSTRACT FROM AUTHOR]

Introduction: Estimating physical activity, sedentary behavior, and sleep from wrist-worn accelerometer data requires reliable detection of sensor nonwear and sensor wear during both sleep and wake. Purpose: This study aimed to develop an algorithm that simultaneously identifies sensor wake-wear, sleep-wear, and nonwear in 24-h wrist accelerometer data collected with or without filtering. Methods: Using sensor data labeled with polysomnography (n = 21) and directly observed wake-wear data (n = 31) from healthy adults, and nonwear data from sensors left at various locations in a home (n = 20), we developed an algorithm to detect nonwear, sleep-wear, and wake-wear for "idle sleep mode" (ISM) filtered data collected in the 2011–2014 National Health and Nutrition Examination Survey. The algorithm was then extended to process original raw data collected from devices without ISM filtering. Both algorithms were further validated using a polysomnography-based sleep and wake-wear data set (n = 22) and diary-based wake-wear and nonwear labels from healthy adults (n = 23). Classification performance (F1 scores) was compared with four alternative approaches. Results: The F1 score of the ISM-based algorithm on the training data set using leave-one-subject-out cross-validation was 0.95 ± 0.13. Validation on the two independent data sets yielded F1 scores of 0.84 ± 0.60 for the data set with sleep-wear and wake-wear and 0.94 ± 0.04 for the data set with wake-wear and nonwear. The F1 score when using original, raw data was 0.96 ± 0.08 for the training data sets and 0.86 ± 0.18 and 0.97 ± 0.04 for the two independent validation data sets. The algorithm performed comparably or better than the alternative approaches on the data sets. Conclusions: A novel machine-learning algorithm was designed to recognize wake-wear, sleep-wear, and nonwear in 24-h wrist-worn accelerometer data that are applicable for ISM-filtered data or original raw data. [ABSTRACT FROM AUTHOR]

Purpose: Sedentary behavior is associated with poor physical function in older adults, which can lead to accelerated skeletal muscle aging (sarcopenia) and premature mortality. We examined the independent and joint effects of sedentary behavior and moderate to vigorous intensity physical activity (MVPA) with measures of physical functioning. Methods: We studied 5408 participants in the REasons for Geographic and Racial Differences in Stroke study who wore a hip-mounted accelerometer over seven consecutive days (2009–2013) and had self-reported and directly observed physical function (time walk, chair stand test) measured during an in-home visit conducted from 2013 to 2016. Results: Greater sedentary time was significantly associated with poorer chair stand and timed walk scores. Substituting 30 min of sedentary time with 30 min of MVPA was associated with significant improvements in chair stands (β −0.57; P = 0.007) and timed walk (β −0.36; P = 0.01). Similar, but less robust, findings were observed for reallocations of sedentary time to light-intensity physical activity. In joint association analyses, high sedentary time in combination with low MVPA (but not in combination with high MVPA) was associated with poorer physical function compared with the referent group (low sedentary time/high MVPA; P < 0.001 for all). Conclusions: Greater time spent being sedentary was associated with worse physical functioning outcomes. However, reallocations of sedentary time to light-intensity physical activity, and especially MVPA, were associated with more favorable physical functioning. Interventions aimed to increase MVPA and reduce sedentary behavior should be a priority, especially among populations at greatest risk for sarcopenia and physical function decline. [ABSTRACT FROM AUTHOR]

Introduction: Efforts to study performance fatigability have been limited because of measurement constrains. Accelerometry and advanced statistical methods may enable us to quantify performance fatigability more granularly via objective detection of performance decline. Thus, we developed the Pittsburgh Performance Fatigability Index (PPFI) using triaxial raw accelerations from wrist-worn accelerometer from two in-laboratory 400-m walks. Methods: Sixty-three older adults from our cross-sectional study (mean age, 78 yr; 56% women; 88% White) completed fast-paced (n = 59) and/or usual-paced 400-m walks (n = 56) with valid accelerometer data. Participants wore ActiGraph GT3X+ accelerometers (The ActiGraph LLC, Pensacola, FL) on nondominant wrist during the walking task. Triaxial raw accelerations from accelerometers were used to compute PPFI, which quantifies percentage of area under the observed gait cadence-versus-time trajectory during a 400-m walk to a hypothetical area that would be produced if the participant sustained maximal cadence throughout the entire walk. Results: Higher PPFI scores (higher score = greater fatigability) correlated with worse physical function, slower chair stands speed and gait speed, worse cardiorespiratory fitness and mobility, and lower leg peak power (| ρ | = 0.36–0.61 from fast-paced and | ρ | = 0.28–0.67 from usual-paced walks, all P < 0.05). PPFI scores from both walks remained associated with chair stands speed, gait speed, fitness, and mobility, after adjustment for sex, age, race, weight, height, and smoking status; PPFI scores from the fast-paced walk were associated with leg peak power. Conclusions: Our findings revealed that the objective PPFI is a sensitive measure of performance fatigability for older adults and can serve as a risk assessment tool or outcome measure in future studies and clinical practice. [ABSTRACT FROM AUTHOR]

Rago, V, Vigh-Larsen, JF, Deylami, K, Muschinsky, A, and Mohr, M. Use of rating of perceived exertion–based training load in elite ice hockey training and match-play. J Strength Cond Res 36(10): 2837–2843, 2022—Training load (TL) based on the subjective rating of perceived exertion (RPE) may be a useful athlete monitoring alternative when wearable technology is unavailable. The aim of this study was to examine the validity of RPE-based TL monitoring in elite ice hockey. A male ice hockey team (n = 18) was monitored using a 200-Hz accelerometer, heart rate (HR) and RPE (0–10 scale), throughout a 4-week competitive period (n = 309 individual observations). Session-RPE (RPE × duration) averaged 244.8 ± 135.2 and 728.6 ± 150.9 arbitrary units (AU) during practice sessions and during official games, respectively. The smallest worthwhile change was 19.8 AU. Within-individual correlations between session-RPE and total accelerations >0.5 m·s−2 (Acctot), accelerations >2 m·s−2 (Acc2), total decelerations >−0.5 m·s−2 (Dectot), decelerations < −2 m·s−2 (Dec2), time > 85% maximum HR, Edwards' TL, and modified training impulse were very large (r = 0.70–0.89; p < 0.001). In addition, correlations between RPE and measures of exercise intensity (Acctot per min, Acc2 per min, Dectot per min, mean HR, and peak HR) were small (r = 0.02–0.29; p < 0.05) except for Dec2 being unclear (p = 0.686). Differences in intensity parameters between RPE range (easy to very hard, 2–7 AU) were small (r = 0.22–0.31; p < 0.05). The session-RPE method can be used as a global indicator of TL in ice hockey. Specific ranges of time-motion and HR intensity variables can be demarcated between RPE categories (easy to very hard; 2–7 AU). Accounting for training volume (session-RPE) more accurately reflects objective methods of TL based on accelerative efforts and HR, than the RPE score (based on the perception of the intensity). [ABSTRACT FROM AUTHOR]

Background and Purpose: Physical activity can delay the progression of self-care disability in older adults residing in living care facilities. Nonetheless, older adults residing in living care facilities spend most of their time sedentary and do not meet the physical activity recommendation, which may result in increasing self-care disability in this population group. In this study, we aimed to determine whether the association between sedentary time and self-care disability was moderated by moderate-to-vigorous physical activity (MVPA) in older adults residing in living care facilities. Methods: Sedentary time and MVPA were both measured with accelerometers. Self-care disability was assessed with the Barthel Index. A multivariate regression model was used to ascertain the effects of the interaction between sedentary time and MVPA on the self-care disability of participants. The Johnson-Neyman technique was then used to estimate the exact MVPA threshold at which the effect of sedentary time on self-care disability became nonsignificant. Results: We found a significant effect of sedentary time on self-care disability (standardized β=−1.66; 95% CI −1.77 to −1.54, P =.013). Results indicated that MVPA moderates the relationship between self-care disability status and sedentary time (standardized β= 1.14; 95% CI 1.13 to 1.14, P =.032). The Johnson-Neyman technique determined that 51 min/day of MVPA would offset the negative effects of sedentary time on self-care disability. Conclusions: Our results suggest physical therapists should focus on reducing sedentary time alongside physical activity to prevent the progression to dependency in octogenarians residing in living care facilities. [ABSTRACT FROM AUTHOR]

Introduction: Higher levels of physical activity are associated with lower cardiometabolic risk. However, the relative contribution of overall activity and the intensity of activity are unclear. Our aim was to determine the relative contribution of overall activity and intensity distribution of activity to cardiometabolic risk in a cross-sectional analysis of apparently healthy office workers and in people with one or more chronic disease. Methods: Clustered cardiometabolic risk score was calculated from mean arterial pressure, high-density lipoprotein cholesterol, triglycerides and HbA1c. Open-source software (GGIR) was used to generate average acceleration and intensity gradient from wrist-worn accelerometer data for two data sets: office-workers who did not have a self-reported medical condition (n = 399, 70% women) and adults with one or more chronic disease (n = 1137, 34% women). Multiple linear regression analyses were used to assess the relative contribution of overall activity and intensity of activity to cardiometabolic risk. Results: When mutually adjusted, both overall activity and intensity of activity were independently associated with cardiometabolic risk in the healthy group (P < 0.05). However, for the CD group, although mutually adjusted associations for average acceleration were significantly associated with cardiometabolic risk (P < 0.001), intensity was not. In healthy individuals, cardiometabolic risk was lower in those with high overall activity and/or intensity of activity, and who also undertook at least 10 min brisk walking. In those with a chronic disease, risk was lower in those who undertook at least 60 min slow walking. Conclusions: These findings suggest interventions aiming to optimize cardiometabolic health in healthy adults could focus on increasing both intensity and amount of physical activity. However, in those with chronic disease, increasing the amount of activity undertaken, regardless of intensity, may be more appropriate. [ABSTRACT FROM AUTHOR]

Introduction: Physical inactivity, excessive total time spent in sedentary behavior (SB) and prolonged sedentary bouts have been proposed to be risk factors for chronic disease morbidity and mortality worldwide. However, which patterns and postures of SB have the most negative impacts on health outcomes is still unclear. This population-based study aimed to investigate the independent associations of the patterns of accelerometer-based overall SB and sitting with serum lipid biomarkers at different moderate- to vigorous-intensity physical activity (MVPA) levels. Methods: Physical activity and SB were measured in a birth cohort sample (N = 3272) at 46 yr using a triaxial hip-worn accelerometer in free-living conditions for 14 d. Raw acceleration data were classified into SB and PA using a machine learning–based model, and the bouts of overall SB and sitting were identified from the classified data. The participants also answered health-related questionnaires and participated in clinical examinations. Associations of overall SB (lying and sitting) and sitting patterns with serum lipid biomarkers were investigated using linear regression. Results: The overall SB patterns were more consistently associated with serum lipid biomarkers than the sitting patterns after adjustments. Among the participants with the least and the most MVPA, high total time spent in SB and SB bouts of 15–29.99 and ≥30 min were associated with impaired lipid metabolism. Among those with moderate amount of MVPA, higher time spent in SB and SB bouts of 15–29.99 min was unfavorably associated with serum lipid biomarkers. Conclusions: The associations between SB patterns and serum lipid biomarkers were dependent on MVPA level, which should be considered when planning evidence-based interventions to decrease SB in midlife. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to assess the association of a wrist-worn, device-based metric of 24-h movement with cognitive function and subjective cognitive complaints among older adults, 60 yr and older. Methods: This is a cross-sectional analysis of the 2011–2012 and 2013–2014 National Health and Nutrition Examination Survey (NHANES) cycles. A wrist-worn ActiGraph GT3X+ accelerometer captured total 24-h movement activity, analyzed as Monitor-Independent Movement Summary units (MIMS-units), and quantified into placement based on an age- and sex-standardized percentile. Cognitive tests in the domains of memory, language/verbal fluency, and executive performance were administered. Test-specific cognitive z -scores were generated. Subjective cognitive complaints included perceived difficulty remembering and confusion/memory loss. Results: The analytical sample included 2708 U.S. older adults (69.5 ± 0.2 yr, 55% female, 20.9% non-White). Multivariable linear regressions revealed those in quartiles 3 (50th–74th percentile) and 4 (≥75th percentile) for their age and sex had higher cognitive function z -scores across all domains compared with those in quartile 1. Logistic regressions demonstrated those in quartiles 3 and 4 also had lower odds of reporting difficulty remembering (adjusted odds ratio [AOR] = 0.52, 95% confidence interval [CI] = 0.31–0.89; AOR = 0.57, 95% CI = 0.37–0.88) and confusion/memory loss (AOR = 0.49, 95% CI = 0.27–0.91; AOR = 0.49, 95% CI = 0.27–0.98), respectively, compared with those in quartile 1. Conclusions: In a representative sample of U.S. older adults, higher cognitive functioning occurs among those that perform total 24-h movement activity at or above the 50th percentile for their age and sex. Future studies should consider movement behaviors across a 24-h period on cognitive health outcomes in older adults. More research exploring prospective associations of MIMS-units and time-use behaviors across midlife and older adulthood that may affect cognitive functioning across diverse populations is needed. [ABSTRACT FROM AUTHOR]