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Kazuhiro Harada, Kouhei Masumoto and Narihiko Kondo

Background: Although the beneficial effects of physical activity and exercise on mental health are well known, the optimal conditions for them for benefitting mental health are still unclear. Engaging in exercise with others might have more desirable effects on mental health than engaging in exercise alone. This study examined the associations between exercising alone, exercising with others, and mental health among middle-aged and older adults. Methods: Baseline and 1-year follow-up surveys were conducted with 129 individuals. Time spent exercising alone or with others was measured using a 7-day diary survey. Total physical activity was objectively measured using an accelerometer. Mental well-being was assessed using the simplified Japanese version of the World Health Organization Five Well-Being Index, and mental distress was assessed using the Japanese version of the Kessler Distress Scale (K6). Results: Cross-lagged and simultaneous effects models revealed that exercising with others positively influenced mental well-being. Exercising alone and total physical activity did not significantly influence mental well-being. Neither total physical activity, exercising alone, nor exercising with others was significantly associated with mental distress. Conclusion: Engaging in exercise with others could be effective in improving mental well-being relative to engaging in exercise alone.

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Kazuhiro Harada, Ai Shibata, Euna Lee, Koichiro Oka and Yoshio Nakamura


Although several studies have examined associations of perceived benefits and barriers with physical activity, no studies have focused on them corresponding to strength-training recommendations for older adults. This study examined the associations among the perceived health benefits of strength training, perceived barriers to strength straining, and stages of change for strength-training behavior in older Japanese adults.


This cross-sectional survey included a random sample of 1144 adults (60–74 years) from the city of Tokorozawa. Stage of change was the independent variable, with perceived health benefits (eg, strength training can reduce body pain) and perceived barriers (eg, facilities are needed for strength training) as dependent variables. Data were analyzed by analysis of covariance and Bonferroni’s multiple comparison.


After adjusting for demographic variables, the perceived health-benefit score for precontemplation was significantly lower than for the other four stages. The perceived barrier scores in the precontemplation and contemplation stages were significantly higher than those in the preparation and maintenance stages.


These results suggest that information about the health benefits for older adults and about the recommended type of strength training might be useful for the development of strategies to promote strength training among older adults.

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Kazuhiro Harada, Ai Shibata, Koichiro Oka and Yoshio Nakamura

This study aimed to examine the association of muscle-strengthening activity with knee and low back pain, falls, and health-related quality of life among Japanese older adults. A cross-sectional survey targeted 3,000 people. The response rate was 52% and 208 respondents did not meet the inclusion criteria. Therefore, 1,351 individuals were analyzed. Muscle-strengthening activity (exercise using equipment and body weight, lifestyle activities), knee and low back pain, falls over the past year, health-related quality of life (SF-8), and potential confounders were assessed. Individuals engaging in exercise using body weight and lifestyle activity (≥ 2 days/week) were more likely to have knee pain. Engaging in exercise using equipment and body weight was associated with higher scores of general health. These results indicate that exercise using equipment and body weight might have a positive effect on health-related quality of life, but muscle-strengthening activities are associated with knee pain in older people.

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Kazuhiro Harada, Sangyoon Lee, Sungchul Lee, Seongryu Bae, Yuya Anan, Kenji Harada and Hiroyuki Shimada

This study aimed to examine whether the expectation for physical activity to minimize dementia risk was associated with physical activity level and whether this association was moderated by perceived high value of dementia prevention among older adults. Participants (n = 2,824) completed questionnaires and wore accelerometers to measure their average daily steps and levels of physical activity. The expectation for physical activity to minimize dementia risk, perceived value of dementia prevention, and potential covariates (expectation of other desirable outcomes, demographics, and health-related factors) were also measured. The main effects of the expectation and perceived value and their interaction were not significant for physical activity variables in generalized linear models. These findings indicate that expecting physical activity in minimizing dementia risk might not be sufficient to influence physical activity behavior regardless of perceived high value of dementia prevention among older adults.

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Kazuhiro Harada, Koichiro Oka, Ai Shibata, Kaori Ishii, Yoshio Nakamura, Shigeru Inoue and Teruichi Shimomitsu

The authors examined the relationship between strength-training behavior and perceived environment in older Japanese adults. An Internet-based survey was conducted of 293 adults age 68.2 ± 2.8 yr. The dependent variable was regular strength-training behavior. The IPAQ environment module, access to facilities for strength training, and home equipment for strength training were environmental factors. Logistic-regression analysis was employed. After demographic variables (gender, age, educational background, household income, body-mass index, self-rated health status, smoking habit, and residential area) were adjusted for, home equipment for strength training (OR = 2.14, 95% CI = 1.50–3.06), access to facilities for strength training (OR = 2.53, 95% CI = 1.32–4.85), and observing active people (OR = 2.20, 95% CI = 1.06–4.58) were positively correlated with regular strength-training behavior. In conclusion, environmental factors associated with strength-training behavior were access to facilities for strength training, having home equipment for strength training, and observing active people.

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Sungchul Lee, Sangyoon Lee, Seongryu Bae, Kazuhiro Harada, Songee Jung, Keitaro Makino and Hiroyuki Shimada

This study examined the association between the estimated glomerular filtration rate (eGFR) and disability incidence according to sedentary time in community-dwelling Japanese older adults. This prospective cohort study sampled 5,104 community-dwelling older adults (≥65 years) enrolled in a health promotion study in a general population. The participants (n = 4,457; ≥65 years) were monitored for inclusion in the long-term care insurance system for 4 years. This study used blood samples to assess eGFR. Cox proportional regression analysis was used to determine predictors of disability. In total, 461 participants (10.3%) became newly certified as needing long-term care insurance services. Cox regression models were adjusted for multiple confounders: eGFR < 45 ml/min/1.73 m2 (hazard ratio = 1.741, 95% confidence interval [1.193–2.539]) and eGFR < 45 ml/min/1.73 m2 with high sedentary time (≥8 hr) (hazard ratio = 4.367, 95% confidence interval [2.021–9.438]) remained significantly associated with disability incidence. Our findings suggest that in the case of chronic kidney disease, the disability incidence rate may be affected by sedentary time.

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Kazuhiro Harada, Hyuntae Park, Sangyoon Lee, Hiroyuki Shimada, Daisuke Yoshida, Yuya Anan and Takao Suzuki

This study examined associations between perceived neighborhood environment and physical activity among frail older adults and whether these associations are moderated by fear of falling. Participants were 238 frail older adults. Daily step counts and duration of moderate-to-vigorous physical activity were measured using an accelerometer. Participants completed the abbreviated Neighborhood Environment Walkability Scale; fear of falling and demographic and health-related factors were measured by a questionnaire. The interaction between crime safety and fear of falling was significantly associated with step count (p = .009) and moderate-to-vigorous physical activity (p = .018) in multiple regression analysis. Stratified according to fear of falling, crime safety was significantly associated with steps (p = .007) and moderate-to-vigorous physical activity (p = .030) in the low fear of falling group. The results suggest that crime safety is associated with physical activity among frail older adults, and this association is moderated by fear of falling.