Highlights

Abstract

Keywords

۱٫ Introduction

۲٫ Methods

۳٫ Results

۴٫ Discussion

۵٫ Conclusions

Funding

Declaration of competing interest

Appendix A. Supplementary data

References

Abstract

Introduction
The Great East Japan Earthquake and the Fukushima Daiichi nuclear power plant accident in March 2011 impacted survivors’ mental health. This study examined whether exercise habits and mental health conditions were associated, and whether the degree of the effect varied depending on time.

Methods
A self-administered questionnaire was sent annually to former residents (born before April 1, 1998) in registered evacuation areas. Exercise habit was evaluated by participants’ exercise frequency, and responses were categorized into “almost never,” “once a week,” and “twice a week and more.” Data were tracked during three periods: fiscal year (FY) 2011–۲۰۱۲, ۲۰۱۲–۲۰۱۳, and 2013–۲۰۱۴٫ The association between baseline habitual exercise and new onset of psychological distress was assessed using the Japanese version of the Kessler 6-item Psychological Distress Scale and logistic regression analysis.

Results
A total of 1304 (5.7%) of 22,741, 1060 (4.7%) of 22,709, and 759 (3.6%) of 21,220 respondents had psychological distress in FY 2011–۲۰۱۲, ۲۰۱۲–۲۰۱۳, and 2013–۲۰۱۴, respectively. An association between exercise and psychological distress was observed in men in FY 2011–۲۰۱۲ (P for trend: 0.010) and in women in FY 2013–۲۰۱۴ (P for trend: 0.026). “Almost never” was associated with onset of psychological distress in men in FY 2011–۲۰۱۲ [odds ratio (OR): 1.317, 95% confidence interval (CI): 1.054–۱٫۶۴۵] and in women in FY 2013–۲۰۱۴ (OR: 1.296, 95% CI: 1.027–۱٫۶۳۶).

Conclusions
Exercise habit was associated with psychological distress, and its effect in time varied according to sex.

۱٫ Introduction

Mental health is defined as “a state of well-being in which every individual realizes his/her own potential, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to her or his community” (WorldHealth Organization, n.d.). Promotion of mental health contributes to overall health; therefore, it is recognized as an essential component of health promotion and included as one of the Sustainable Development Goals of the United Nations (United Nations, n.d.). Thus, actions to identify protective or inhibiting factors of mental health have recently accelerated.

Previous studies have focused on various lifestyle factors such as obesity, exercise, and drinking as factors associated with mental health (Jonsdottir, Rödjer, Hadzibajramovic, Börjesson, & Ahlborg, 2010; Xu, Anderson, & Courtney, 2010). In particular, exercise has recently been reported to lead to moderate increases in self-reported positive-activated affect (Reed & Buck, 2009) and to alleviating symptoms of depression (Craft & Perna, 2004). The mechanisms by which exercise positively affects mental health include physiological and biochemical effects. Exercise may also be an alternative to psychotherapy for improving mental health (Mikkelsen, Stojanovska, Polenakovic, Bosevski, & Apostolopoulos, 2017). The government of Japan established exercise guidelines for citizens in which exercise is recommended for citizens of all ages, and performing exercise for 30 min or more at least two days a week is encouraged (Ministry of Health, Labour and Welfare, 2013).