Too much is too little: Estimating the optimal physical activity level for a healthy mental state

Abstract

IntroductionAlthough physical activity and exercise are generally thought to have favorable effects on mental health, excessive physical activity may have unfavorable effects. In this study, the associations between physical activity and the states of mental health with U-shaped dose–response curves were hypothesized, and the ranges of physical activity resulting in optimal effects on mental health were investigated.MethodsA cross-sectional survey was conducted on 1,237 adult volunteers in 2017 and 2018. Of these volunteers, 526 participants validly answered the self-administered questionnaires asking about physical activity, depression, anxiety, resilience, insomnia vulnerability, and life events. A comparison of mental health measures by physical activity levels and quadratic equation model regressions were performed.ResultsNo significant linear associations between physical activity levels and mental health measurements were observed; however, the U-shaped, quadratic equation models indicated a significance. The following levels of physical activity per week optimized the mental health measurements values of the participants: 6,953 MET-minutes and 25.70 h for depression, 5,277 MET-minutes and 21.60 h for state anxiety, 5,678 MET-minutes and 22.58 h for trait anxiety, 25.41 h for resilience, and 9,152 MET-minutes and 31.17 h for insomnia vulnerability.ConclusionPhysical activities in the optimal range were associated with more favorable mental health measurements. Physical activities that were too much or too long and outside of the optimal range were associated with less favorable mental health measurements.

Editorial: Advances in the understanding of the affective and cognitive effects of physical activity, exercise, and sports

“…Their research revealed an inverted-U shaped correlation between weekend physical activity and academic achievement, with a noted sex difference in the optimal duration of exercise-−2 h for males and 1 h for females. The inverted-U shape finding aligns with another recent study by Shimura et al ( 2023 ), which examined the association between the total duration of weekly physical activity and mental health outcomes. Moreover, the gender-differentiated impact in the above study is further explored by Wu et al , who found significant associations between physical activity levels and depressive symptoms in males but not in females.…”

Mediating Effects of Trait Anxiety and State Anxiety on the Effects of Physical Activity on Depressive Symptoms

“…Previous studies have indicated the existence of an optimal physical activity time regarding the influence of physical activity intensity on mental health [ 29 ]. There are also reports that this optimal physical activity time is associated with lower depressive symptoms [ 30 , 38 ]. In the present study, we hypothesized that physical activity time affects depressive symptoms via state and trait anxiety, and that an optimal physical activity time exists in this effect, and tested this hypothesis by a path analysis.…”

“…Although the association between physical activity and mental health has been reported in various studies, as described in the Introduction section, the dose-response relationship between physical activity and mental health has not been clarified, which makes specific interventions, such as exercise therapy, difficult. Whereas positive associations between physical activity and mental health have been reported, it was also reported that excessive physical activity levels exacerbate mental health burden as much as no physical activity at all [ 29 , 30 ]. In addition, a U-shaped association between physical activity for leisure and depressive symptoms among Japanese workers [ 38 ] was also reported.…”

“…Subjects self-rated how many days per week and how much time per day they were active in each of the following three categories: strong physical activity, moderate physical activity, and walking continuously for at least 10 min. As existing research suggests that neither under- nor over-physical activity is desirable for mental health and that there is an optimal physical activity time [ 29 , 30 , 38 ], the weekly total physical activity time (hours) and PHQ-9 values obtained here were used to perform a regression analysis in a quadratic equation model. This regression analysis was used to obtain the optimal physical activity time (hours per week), and the difference from the optimal physical activity time (DOT) was used as an indicator for statistical analysis.…”

“…Additionally, there is a lack of knowledge regarding the dose-response association between physical activity and its effects on anxiety and depressive symptoms [ 13 ]. However, the existence of an optimal physical activity time and intensity for mental health was suggested in recent studies [ 29 , 30 ]. While insufficient physical activity has been shown to negatively impact mental health, as aforementioned, excessive physical activity may also be harmful to mental health [ 31 ] because of the stimulation of cytokines [ 32 ] and cortisol systems [ 33 ], known as an overtraining syndrome.…”