Increasing light-intensity physical activity (LPA) or moderate-to-vigorous physical activity (MVPA) and decreasing sedentary behavior (SB) are important to maintain cognitive function in older adults. However, there is a lack of studies examining the influence of replacing time spent in SB, LPA and MVPA on cognitive function. Therefore, this study applied an isotemporal substitution (IS) model approach to examine the associations of objectively measured SB, LPA, and MVPA on multiple cognitive functions in older adults. We analyzed data from 145 older persons (mean age, 75.1 ± 4.5 years; 61.4% women) in Kasama City, Japan. We assessed SB, LPA, and MVPA for seven consecutive days with a triaxial accelerometer. To evaluate the cognitive function, we used the Five-Cog test (character position referencing task, category cued recall task, clock drawing task, animal name listing task, and analogy task). The IS model of the multiple regression analysis was used to examine the effects of replacing time spent on one activity type with 30 minutes per day of SB, LPA, and MVPA on multiple cognitive functions, adjusting for age, gender, body mass index, education, smoking, sleep duration, history of stroke, medication for hypertension, dyslipidemia, and diabetes and accelerometer wear time. The results showed that reallocation from SB to LPA was significantly related to the category cued recall task score (B = 0.69, 95% confidence interval 0.07 - 1.31). In contrast, other reallocations were not associated with any cognitive tasks. The results suggest that substituting SB with LPA is positively associated with verbal episode memory among older Japanese adults.

Introduction: The purpose of this study was to investigate the effects that a group exercise activity managed by elderly volunteers would have on the physical function of older women after they participated in a formal exercise program taught by fitness experts.

Methods: Subjects were 47 community-dwelling older women who had completed a 3-month exercise program led by expert instructors in Kasama City, Ibaraki. After completing this exercise program, 28 subjects continued to participate in a group exercise activity led by elderly volunteers for approximately 11 months. The remaining 19 subjects did not join the group activities after the formal program. In both the initial, expert-led exercise program and the subsequent, volunteer-led group activity, subjects mainly engaged in the square-stepping exercise, which is a novel exercise for improving lower extremity physical function. In order to assess participants' physical function, we conducted five physical performance tests at both the baseline and follow-up; the former is the last day of the exercise program and the latter is approximately a year after the baseline.

Results: Two-way ANOVA demonstrated a significant interaction in the timed up and go test (P=0.003). The performance of subjects who had participated in the volunteer-managed group activity improved between the baseline and follow-up tests (P=0.007).

Conclusion: Participating in a group exercise activity managed by elderly volunteers can improve mobility skills of older women who had previously completed a formal exercise program led by expert instructors.

We examined the relationship between the timing of habitual physical activities and sleep quality in older adults. The subjects were Japanese community-dwelling older adults (n=49, average age 70.1±3.5 years; men: 36.7%). We measured habitual physical activity using a 3-axis accelerometer (HJA-350 IT, Omron) for a week. Timing of physical activity was classified into the following three periods: (1) morning: waking to 11:59, (2) afternoon: 12:00 to 17:59, and (3) night: 18:00 to bedtime. We also categorized the intensity of habitual physical activity during 2 sessions as either (1) low (1.6-2.9 METs) or (2) moderate-to-vigorous (≧3.0 METs) intensity. The subjective sleep parameters were assessed using the Pittsburgh Sleep Quality Index (PSQI). We used a forced-entry multiple regression analysis to investigate the relationships between subjective sleep parameters and the timing of physical activities. Forced-entry multiple regression analysis revealed that sleep latency and PSQI global score were positively correlated with low-intensity physical activity at night. However, there was no significant correlation with moderate-to-vigorous activity. These results suggest that low-intensity habitual physical activity at night would be one useful and modifiable factor to improve sleep quality in the elderly.

The purpose of this study was to examine the association of muscle mass and muscle strength with mobility limitation and history of falls in community-dwelling older adults. This cross-sectional study included 420 older adults (207 men, 213 women, 73.7 ± 5.2 years). The participants were classified to following four groups according to their appendicular skeletal muscle mass index (AMI) which was evaluated by bioelectric impedance analysis for skeletal muscle mass in the arms and legs and appendicular skeletal muscle strength Z-score (ASZ) which was calculated from hand-grip strength for upper extremity and peak reaction force during sit-to-stand movement for lower extremity: 1) Low AMI and Low ASZ, 2) Low AMI alone, 3) Low ASZ alone, and 4) Normal. Mobility limitation and history of falls were assessed as a self-reported questionnaire. We used a poisson regression analysis with an adjustment for age, body mass index, knee pain, and back pain. The prevalence of mobility limitation was significantly higher at Low AMI and Low ASZ (relative risk, RR = 5.09, 95% confidence interval, CI 2.08–12.46) and Low ASZ alone (RR = 4.79, 95% CI 2.01–11.39) in men and Low AMI and Low ASZ (RR = 1.70, 95% CI 1.01–2.88) in women than Normal. History of falls was significantly associated with Low ASZ alone (RR = 2.00, 95% CI 1.02–3.91) just in men. These results suggest that low muscle strength per weight rather than low muscle mass per height is an important risk factor to increase mobility limitation in both genders and falls in men.

The purpose of this study was to elucidate the effects of whole-body vibration training (WBVT) on knee function and physical performance in middle-aged and older Japanese women who suffered from knee osteoarthritis (OA) and knee pain. Thirty-eight middle-aged and older Japanese women (aged 50-73 years) with knee OA and knee pain were divided into two groups: (1) a WBVT group (n = 29) engaging in WBVT 3 times a week for 8 weeks, and (2) a control group (C group, n = 9) performing exercises at home. The WBVT program consisted of a warm-up, strength training mainly of the quadriceps and their surrounding muscles and cool-down exercises. In the WBVT group, there were no dropouts, and there were significant improvements in the physical function (Cohen’s d = 0.28) and total score (Cohen’s d = 0.25) of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). There were also statistically significant improvements in all lower-extremity function tests (5-times sit-to-stand, timed up and go, standing time from a long sitting position, sit and reach, 4-way choice reaction time; Cohen’s d = 0.34-1.24). The item that changed significantly in the C group, however, was only the sit and reach (Cohen’s d = 0.52). In addition, all items in the Japanese Orthopaedic Association Score (JOA score) improved significantly (Cohen’s d = 0.63-0.67) in the WBVT group. In conclusion, the 8-week WBVT program can safely improve knee function and physical performance in middle-aged and older Japanese women who suffer from knee OA and knee pain.

This study examined relationships between physical activity and sleep relative to leisure-time, household, and occupational physical activity in community-dwelling, older adults. From 3,000 randomly chosen community-dwelling, adults, aged 65-85 years, we recruited 509 eligible subjects (mean age 73.2 ± 5.1 years). We assessed nocturnal sleep duration, sleep onset latency and subjective sleep quality over the previous month through a questionnaire. Physical Activity Scale for the Elderly was used to assess leisure-time, household, and occupational physical activity. Items pertaining to sleep were expressed as dichotomous variables (good/poor), and each physical activity score was divided into two categories based on activity level. To investigate the relationship between sleep (dependent variable) and physical activity (independent variable), we used a logistic regression analysis, controlling for age, gender, living arrangement, depressive symptoms, and cognitive function. Prolonged sleep latency was significantly related to no participation in low intensity exercise (OR 2.14; 95% CI 1.42-3.21) and muscle strength exercise (OR 1.99; 95% CI 1.06-3.74). Our data suggest that not participating in low intensity exercise or muscle strength exercise may be associated with difficulty initiating sleep in older adults.

The purpose of this study was to examine whether volunteering as exercise instructors over a continuous period of time affected the physical and cognitive functions of community-dwelling, elderly women. Longitudinal analysis was conducted on data from 18 volunteer leaders (Leader group) aged 65-79 years (69.6 ± 3.9 years) and 18 age-matched survey participants (Control group). We evaluated physical function using 8 physical performance tests along with their standardized total score, and we evaluated cognitive function using the Five Cognitive Function Test. We used two-way ANOVA to examine the effectiveness of engaging in a yearlong volunteer activity and Cohen's d for effect size. There were significant interactions in timed up and go, hand working with pegboard, standardized score of performance tests and the Five Cognitive Function Test score (P < 0.05). The Leader group improved significantly in sit and reach (d = 0.55), 5-repetition sit-to-stand (d = 0.77), timed up and go (d = 0.77), 5-m habitual walk (d = 0.88), 4-way choice reaction time (d = 0.86), standardized score of performance tests (d = 0.96) and the Five Cognitive Function Test score (d = 0.93). Although the Control group also improved significantly in some tests, the effect size tended to be lower: sit and reach (d = 0.49), hand working with pegboard (d = 0.57), standardized score of performance tests (d = 0.38) and the Five Cognitive Function Test score (d = 0.54). These results suggest that volunteering as an exercise instructor improves volunteers' physical and cognitive functions.

The purpose of this study was to examine the effects of 9 weeks of resistance training, with and without static acceleration training (AT), on participants' lower-limb muscle strength, power, and physical function. Healthy participants (19 men and 28 women), aged 65-75 years, were assigned to a static AT group (AT, n = 31) or a non-AT control group (C, n = 16). The AT group and the C group trained three times/week for 9 weeks. The AT group performed unloaded static AT and low-intensity aerobic activity. The C group performed dynamic weight-bearing resistance training without whole-body vibration and the same aerobic activity as the AT group. We collected and analyzed data from 45 participants (AT = 30, C = 15) who completed pre- and post-tests. There was no significant Group × Time interaction on any measurements of lower-limb muscle strength, power, or physical function. Significant time effects were observed in the following tests:isokinetic knee extensor and flexor peak torque, 5-time sit-to-stand, usual gait speed, timed up and go, standing time from a long sitting position, and sit and reach. All of these 7 variables showed positive changes. These results suggest that static AT is a suitable training method having approximately the same efficiency as conventional, weight-bearing, dynamic resistance training for improving lower-limb muscle strength and power, mobility, and flexibility in community-dwelling Japanese older adults.

The purpose of this study was to determine whether hand-grip strength (HGS) can be a significant discrimination factor of mobility limitation (ML) among older adults. Cross-sectional analysis was conducted on data from 939 community-dwelling older adults, aged 65-96 years (74.4 ± 6.4 yr, 266 men, 673 women). ML was defined as self-reported difficulty in walking 400 m, climbing 10 steps, and rising from a chair. Trained testers assessed standardized measurements of HGS and lower extremity performance score (LEPS) calculated by four tests (i.e., tandem stance, 5-chair sit-to-stand, alternate step, and timed up & go). Receiver operating characteristic (ROC) analysis was conducted to identify discrimination power of HGS and LEPS for ML. The areas under the ROC curves (AUCs) of HGS and LEPS for ML were 0.82 and 0.87 in men; 0.70 and 0.85 in women, respectively. No significant difference was detected between the AUCs of HGS and LEPS (P = 0.12) in men, whereas in women, the AUC was significantly lower in HGS than LEPS (P < 0.001). The optimal HGS cut-off values for ML were 31.0 kg (sensitivity 75%, specificity 81%) for men and 19.6 kg (sensitivity 73%, specificity 57%) for women. In men, the HGS test could be as useful as LEPS for identifying ML. In women, discrimination power for ML by HGS alone was considered acceptable; however, a combination of HGS and lower extremity performance tests could be more useful for monitoring the hierarchical levels of physical frailty.

The vertical ground reaction force (GRF) parameters in a sit-to-stand movement are useful for measuring lower-limb muscle strength and power in older adults. The purpose of this study was to examine which GRF parameters would be more strongly associated with a person's physical functioning, history of falls, fear of falling and mobility limitations, all of which are known to be related to lower-limb muscle strength and power. We performed cross-sectional analyses on 363 community-dwelling older adults, which included 160 men and 203 women, aged 65-85 years (73.4 ± 5.3 years). Five parameters were measured: peak reaction force, two rate of force development and two time-related parameters. Their rate of force development was relatively higher correlated with results from timed “up and go” tests, standing times from a long sitting position and 4-way choice reaction times (partial r = -0.37 ∼ -0.52); these tests were accompanied with a dynamic movement of lower-limb; than their peak reaction force and time-related parameters. The rate of force development were poorer in subjects reporting falls, a fear of falling or a mobility limitation compared with those reporting no falls, fear of falling or mobility limitation. These results suggest that measuring the rate of force development in a sit-to-stand movement provide a better assessment of lower-limb muscle strength and power.