Objective: The purpose of this study was to investigate the association between sedentary behavior and mental
health among Japanese workers.
Methods: This study was a cross-sectional study. We collected survey data from annual health check-ups conducted in Meiji Yasuda Shinjuku Medical Center in Tokyo, Japan. The study participants comprised 9335 Japanese workers（5192 men and 4143 women; mean age 46.9 ± 10.8 years）without any psychiatric disease. A self-reported questionnaire gathered data on sedentary behavior, mental health（K6）, moderate to vigorous physical activity （MVPA, IPAQ）and potential confounding factors. Poor mental health was defined as a K6 score ≥ 13 points. Subjects were divided into four groups based on the total sitting time of the day. The odds ratio（OR）and 95% confidence interva（l 95% CI）of poor mental health were calculated using multiple logistic regression analysis adjusted for socioeconomic factors, lifestyle, MVPA and other potential confounding factors.
Results: OR（95% CI）of poor mental health for men who had 12 or more hours per day of sitting time was 2.74
（1.24 － 6.04）. It was also confirmed that OR tended to increase the longer the sitting time（tend P < 0.01）. On the other hand, OR of poor mental health for women who had between 6 and 9 hours of sitting time per day was 0.52
（0.28 － 0.98）. However, there was no significant linear trend.
Conclusion: In Japanese male workers, long sitting time is associated with poor mental health, even after adjustments for socio-economic factors, lifestyle, occupational factors, and MVPA. Compared to the group with under 6 hours of sitting time per day, the group with over 12 hours per day suffered more than twice as much poor mental health. On the other hand, no significant linear trend in the relationship between sitting time and poor mental
health was found among women.
Chronic physical inactivity has a potential to induce negative affective states and impair cognitive function. In
contrast, it has been suggested that exercise at moderate intensity improves affective states and cognitive function.
Nevertheless, moderate exercise may induce stress responses in those who are physically inactive, which implies that moderate exercise may not be appropriate to improve affective states and cognitive function for the inactive population.
Stretching is a common form in general fitness, and may reduce anxiety and improve affective states. Hence, we
expected that acute stretching is beneficial to affective states and cognitive function, particularly in inactive people.
However, it is unclear how stretching alters affective states and cognitive function in inactive people. The purpose of this study was to examine the effects of acute stretching on affective states and cognitive function in inactive people.
Nineteen subjects participated in the present study. They performed a cognitive task（Trail Making Test: TMT）
and answered questionnaires（Mood Check List-short form 2: MCL-S.2 and WASEDA）before and after stretching
or rest （control）for 10 min. The order of stretching and control was counter-balanced. MCL-S.2 was used to assess
pleasantness, relaxation, and anxiety, and WASEDA was used to assess negative affect, positive engagement, and
tranquility. Saliva levels of immunoglobulin A（IgA）were measured before and after stretching or rest.
Reaction time in the TMT significantly decreased after stretching. Pleasantness and positive engagement increased after stretching. These alterations were not observed in the control condition. Stretching did not affect
salivary IgA. These results suggest that improvements in cognitive performance may be associated with positive
affective states induced by acute stretching. In conclusion, the present results suggest that stretching improves affective states and cognitive function in inactive people.
Many studies demonstrate that exercise improves mental health. However, the neural mechanisms underlying this
improvement remain unclear. In the present study, we examined the effect of hip-hop dance training on neural
response to emotional stimuli using the functional magnetic resonance imaging（ fMRI） in healthy young adults.
Twenty-two university students who did not regularly exercise were assigned to either the training group（ 7 men and 4 women） or the control group （5 men and 6 women）. The training group performed short-term hip-hop dance
training, consisting of a 60-min class 3 times per week for 3 weeks. The control group maintained their normal daily
activity. Acquisition of fMRI was performed while the participants viewed pleasant, unpleasant, and neutral slides
pre- and post-training. The contrasts of pleasant vs. neutral and unpleasant vs. neutral were calculated, and activity
changes between the pre- and post-training periods were compared between the two groups. As a result, hip-hop
dance training increased brain activity in the posterior parietal and occipital cortices, for both the pleasant and
unpleasant emotional stimuli, suggesting that the training facilitated visual attention. Moreover, increased activity
was observed in the temporoparietal junction（TPJ）and insula specifically for pleasant emotional stimuli, suggesting
empathetic understanding of pleasant emotion, whereas no activity increase occurred in regions related to emotion
generation for unpleasant emotional stimuli. These changes may be associated with psychological benefits of exercise.