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Background Deteriorated skeletal muscle condition, including sarcopenia, is a risk factor for disability in older adults. Promoting physical activity is a useful treatment for sarcopenia. However, optimal intensity of physical activity according to sarcopenia characteristics is unclear. Methods This longitudinal cohort study enrolled 2149 community‐dwelling older adults (women 55.7%, mean age: 75.5 ± 4.0 years). Five‐year disability incidence defined by Japanese long‐term care insurance certification and accelerometer‐measured physical activities (light‐intensity physical activity [LPA] and moderate‐to‐vigorous intensity physical activity [MVPA]), which were adjusted for potential confounders, was analysed using cox‐proportional hazard model stratified by sarcopenia characteristics based on the diagnostic algorithm by the Asian working group for sarcopenia (robust, low physical function, low muscle mass, and sarcopenia). The sarcopenia group was defined as low muscle mass and low physical function (weakness and/or slowness). The low muscle mass and low physical function groups were each defined by these characteristics alone. Muscle mass was analysed via bioelectrical impedance analysis. Each intensity of physical activity times was divided by median values. Results The disability incidence rate was 15.4%, excluding those who could not be followed up. Mean LPA times were 43.8 ± 18.0, 45.6 ± 17.5, 45.4 ± 16.6, 40.8 ± 18.6, and 41.4 ± 18.5 min/day and MVPA times were 24.6 ± 17.6, 26.3 ± 18.3, 27.2 ± 17.3, 21.6 ± 16.3, and 21.5 ± 16.4 min/day in all participants, the robust, low muscle mass, low physical function, and sarcopenia groups, respectively. For all participants, higher MVPA was associated with disability incidence [hazard ratios (HR), 0.63; 95% confidence interval (95% CI), 0.49–0.81; P

Gait speed is an important indicator of functional decline in older adults. Recently, daily gait speed has been assessed using accelerometers. However, it is unclear whether this parameter can predict the decline in functional abilities. This study investigates whether daily gait speed can be a predictor of incident disability risk as well as in-laboratory gait speed. A sample of 1860 older adults (Male: 728, Female: 1132; 70.1 ± 6.2 years) were instructed to wear accelerometers on the waist. The association between daily gait speed for two weeks and incident disability during a two-year period was analyzed by using the cut-off value for screening prefrailty in the previous study (106.3 cm/s). Furthermore, the associations with in-laboratory gait speed (cut-off value: 100 cm/s), number of steps (cut-off value: 6342.2 steps/day), and incident disability were also analyzed. Cox proportional hazards analysis showed a significant hazard ratio of low daily gait speed (HR, 2.97; p = 0.02) comparable to that of low in-laboratory gait speed (HR: 2.53; p = 0.01). Conversely, the number of steps had no significant association with incident disability (HR: 1.99; p = 0.12). These results suggest that daily gait speed can be a predictor of incident disability risk in older adults.

Prefrailty is an intermediate stage between non-frailty and frailty. It is associated with an increased risk of progression to frailty, which makes it important to screen older adults for prefrailty at an early stage. This study verified whether daily gait speed and number of steps measured using a tri-axial accelerometer could be used to identify prefrailty. In total, 1692 Japanese community-dwelling older adults were divided into robust (n = 1032) and prefrail (n = 660) groups based on the Kihon Checklist, which is a self-administered questionnaire. Both daily gait speed and number of steps were measured for two weeks using tri-axial accelerometers. We also calculated the area under the ROC curve and the cut-off values for these parameters. Our results showed that the cut-off value for daily gait speed was 106.3 cm/s, while that for number of steps was 6342.2. In addition, we found that the combined assessment of both cut-off values was a more effective way to screen older adults with prefrailty status compared to either parameter alone. This is also considered an effective way to reduce national expenditures for daily care assistance.

Prefrailty is an intermediate stage between non-frailty and frailty. It is associated with an increased risk of progression to frailty, which makes it important to screen older adults for prefrailty at an early stage. This study verified whether daily gait speed and number of steps measured using a tri-axial accelerometer could be used to identify prefrailty. In total, 1692 Japanese community-dwelling older adults were divided into robust (n = 1032) and prefrail (n = 660) groups based on the Kihon Checklist, which is a self-administered questionnaire. Both daily gait speed and number of steps were measured for two weeks using tri-axial accelerometers. We also calculated the area under the ROC curve and the cut-off values for these parameters. Our results showed that the cut-off value for daily gait speed was 106.3 cm/s, while that for number of steps was 6342.2. In addition, we found that the combined assessment of both cut-off values was a more effective way to screen older adults with prefrailty status compared to either parameter alone. This is also considered an effective way to reduce national expenditures for daily care assistance.

Gait speed in laboratory settings (in-laboratory gait speed) is one of the important indicators associated with the decline in functional abilities in older adulthood. Recently, it has become possible to measure gait speed during daily living (daily gait speed) using accelerometers. However, the relationship between these two gait speed parameters is unclear. This study aimed to compare in-laboratory gait speed, measured by a sheet-type pressure sensor, and daily gait speed, measured by an accelerometer, in healthy community-dwelling older adults. Participants were aged ≥60 years, residing in Takahama city, Aichi, Japan. To calculate daily gait speed, participants were instructed to wear a tri-axial accelerometer on their waist. A total of 1965 participants were included in the final analysis. The results showed a weak association (r = 0.333, p

Objective The purpose of the study was to estimate, using an isotemporal substitution model, the effect of replacing sedentary behavior (SB) with physical activity on the incidence of disability in community-dwelling older adults. Methods This 2-year longitudinal cohort study enrolled 3691 community-dwelling older adults (57.2% women; mean age = 74.0 [SD = 5.0] years). Individuals with dementia, stroke, Parkinson disease, depression, low Mini-Mental State Examination scores, dependence on basic activities of daily living, and missing data were excluded. Physical activity and potential confounding factors were investigated as a baseline survey of disability incidence, defined by Japanese long-term care insurance certification, for 2 years in 2 regions. Physical activity data (SB, light-intensity physical activity, and moderate- to vigorous-intensity physical activity [MVPA]) were measured using triaxial accelerometers for 14 days, and daily mean time spent in each physical activity parameter was computed in increments of 10 minutes. The relationship between baseline physical activity and disability incidence adjusted for potential confounders was analyzed using multilevel Cox proportional hazards regression analyses with an isotemporal substitution model. Results The disability incidence rate was 3.8%, excluding individuals who could not be followed-up. Replacing 10 minutes of SB per day with MVPA was associated with a decreased disability incidence (hazard ratio = 0.870; 95% CI = 0.766–0.988), whereas no evidence was found for replacing SB with light-intensity physical activity (hazard ratio = 0.980; 95% CI = 0.873–1.10). Conclusions Replacing SB with MVPA was associated with a lower risk of disability. These findings are helpful for establishing disability prevention strategies. Impact These results suggest that feasible changes in daily behavior, such as replacing 10 minutes of SB with MVPA daily, might have a protective effect on disability incidence. Clarifying these associations is useful for developing disability prevention strategies and may help reduce the incidence of disability in community-dwelling older adults.

[Purpose] This study evaluated gait parameters and foot pressure in two regions of the feet among older females with different personal care support needs to analyze factors that contribute to higher support requirements. [Subjects and Methods] Thirty-two older females were divided into support-need and care-need level groups. Gait parameters (speed, cadence, step length, step width, gait angle, toe angle, double support phase, swing phase, and stance phase) and foot pressure during a 5-m walk were measured and analyzed in the two groups. [Results] The percentage of the double support phase on both feet and the right stance phase were significantly higher in the care-need level group, while that of the right swing phase was significantly lower than that of the support-need level group. Additionally, the phase showing peak pressure on the left rear foot was significantly delayed and the left forefoot pressure in the terminal stance was significantly lower in the care-need level group than in the support-need level group. [Conclusion] These findings show that the temporal duration parameters and foot pressure on a particular side were significantly different between the two groups and suggest that these differences were associated with a higher care level.

[Purpose] A trial was conducted to examine the effects of promoting daily physical activity, tailored to specific living situations, on physical and mental health indicators in older adults. [Participants and Methods] Participants in the 'Intervention' group (N=21) wore accelerometers during the 12-week trial period, and for one week during preliminary and follow-up surveys. Based on their physical activity levels as measured by accelerometers, participants were given instructions to increase their daily physical activity. Participants in the 'Control' group (N=18) wore the accelerometer only during the preliminary and follow-up survey. [Results] Number of steps increased significantly in the intervention group and a significant decrease in light physical activity time was observed in the control group. No such decrease was observed in the intervention group. With regard to health-related quality of life, significant interactions were observed between groups based on the 36-Item Short-Form Health Survey Mental Component Summary score, and some sub-items. A combined analysis of both groups found a significant positive correlation between the change in light physical activity time and the Mental Component Summary score. [Conclusion] An increase in daily physical activity was considered to have a sustained bolstering effect on mental health.

The ubiquity of wearable sensors now enables us to measure a user’s walking speed outside of a laboratory or clinical setting, during activities of daily living. However, this technology is recent, and researchers have yet to determine the locations on the body that produce the most accurate data from these sensors. This study aims to compare the accuracy of average walking speed estimation measured using acceleration data from three body landmarks: wrist, pelvis, and ankle. Estimation models are derived from the gait data of 247 healthy adults using stepwise linear multiple regression analyses. The absolute value of the within-participant mean of errors between actual average walking speed and estimated average walking speed is computed and compered across landmarks. The ankle is the most accurate locations from which to estimate average walking speeds from acceleration signals, whereas the wrist was the least accurate locations. Walking speed is an important measure of health and function, especially in older people, and accurately estimating walking speeds in daily life may be helpful in predicting health outcomes in the elderly.

Methods to estimate step length using accelerometers are gaining attention in recent times. However, the influence of the sensor location on the accuracy of step length estimation is still unknown for models fabricated in a uniform manner. Therefore, the purpose of this study was to compare the accuracy of step length estimations among the following three body parts: ankle, pelvis, and wrist. Ten time-normalized acceleration signals from one gait cycle were obtained from 247 healthy adults aged 20 to 77 while walking barefoot at a comfortable, self-selected speed. Linear multiple regression analyses with leave-one-participant-out cross validation technique were used to build the algorithms. The absolute value of mean error for each participant (AME) was computed to compare the accuracies among the body parts. Mean (standard deviation) values of AME for each part were as follows: ankle, 2.66 (2.24) cm; pelvis, 3.09 (2.39) cm; and wrist, 4.05 (3.01) cm. Statistical analyses revealed significant differences for the ankle–wrist and pelvis–wrist estimations. We found that step length can be estimated from the acceleration signal of the ankle or pelvis with almost the same accuracy (approximately 3 cm of average error between participants). Also, estimation of step lengths with the acceleration signals obtained from the wrist needs to be conducted more carefully than those obtained from the ankle or pelvis.

Amyloid fibrils are fibrillar aggregates of denatured proteins associated with a large number of amyloidoses. The formation of amyloid fibrils has been considered to occur by nucleation and elongation. Real-time imaging of the elongation as well as linear morphology of amyloid fibrils suggests that all elongation events occur at the growing ends of fibrils. On the other hand, we suggested that monomers also bind to the lateral sides of preformed fibrils during the seed-dependent elongation, diffuse to the growing ends, and finally make further conformation changes to the mature amyloid fibrils. To examine lateral binding during the elongation of fibrils, we used islet amyloid polypeptide (IAPP), which has been associated with type II diabetes, and prepared IAPP modified with the fluorescence dye, Alexa532. By monitoring the elongation process with amyloid specific thioflavin T and Alexa532 fluorescence, we obtained overlapping images of the two fluorescence probes, which indicated lateral binding. These results are similar to the surface diffusion-dependent growth of crystals, further supporting the similarities between amyloid fibrillation and the crystallization of substances.