Isotemporal substitution of sedentary time with physical activity and its associations with mental health of Japanese office workers / 体力科学

ABSTRACT

In this study, we performed isotemporal substitution analysis to examine potential associations of sedentary time and physical activity with mental health of Japanese office workers. This study employed a cross-sectional study design. We analyzed data on 108 Japanese office workers (mean age 46.4 ± 9.8 years; 64.8% women) in the study. Sedentary behavior (SB; ≤ 1.5 metabolic equivalents [METs]), light-intensity physical activity (LPA; 1.6–2.9 METs), and moderate-to-vigorous physical activity (MVPA; ≥ 3 METs) were measured with a triaxial accelerometer. Two kinds of self-administered questionnaires, the mental stress (K6) and work engagement (Utrecht Work Engagement Scale), were used to assess negative/positive mental health. A cut-off score of 5 or higher on the K6 was used to define persons with mental stress. Logistic and multiple regression analyses using an isotemporal substitution model was applied to demonstrate the association between replacing 30 min/d of SB with an equal amount of time spent on LPA or MVPA and mental stress and work engagement; the studied covariates were age, sex, body mass index, economic status, education, and overtime hours. The results showed that replacing SB with MVPA for 30 min/d was significantly decreased odds ratio (OR) of mental stress (OR = 0.38, 95% confidence interval 0.15–0.92), whereas the replacement was not associated with work engagement (B = 0.16, P = 0.38). In contrast, substitution of SB with LPA was not associated with mental stress and work engagement. These results indicate that substituting sedentary time with MVPA could be associated with mental stress of Japanese office workers.