Is sitting bad for your mental health?

Kirk, Alison and Knowles, Ann-Marie and Hughes, Adrienne (2014) Is sitting bad for your mental health? In: American College of Sports Medicine Annual Meeting, 2012-05-29 - 2012-06-02.

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Sedentary behaviors are any waking activity characterized by energy expenditure ≤ 1.5 metabolic equivalents and sitting or reclining posture. People currently spend a substantial amount of time in sedentary behaviors and this has been linked to poor physical health, independent of physical activity (PA) levels. Little is known about associations of sedentary behaviors with mental health and quality of life. Purpose: To explore the association between objectively measured sedentary behavior and perceived mental health and quality of life. Methods: 42 adults (19M, 23F); mean age 38yrs (range 18-67); BMI 24.8kg/m2 (range 18.7-33.8) wore an activPAL monitor 24h/day for 1 week and completed the Hospital Anxiety and Depression Scale (HADS) and SF-12 Health Survey. The activPAL monitor measures posture and classifies an individual’s activity into time spent sitting/lying, standing and stepping. Sedentary time was defined as time spent sitting/lying by subtracting participant recorded sleep time from activPAL recorded sitting/lying time. Average weekday and weekend day sitting/lying time was computed. Differences in HADS and SF-12 subscale scores were examined across sitting/lying groups (Low less than 8hrs/day, Medium 8-10hrs/day, High more than 10hrs/day) using ANCOVA with a measure of PA (step count) included as a covariate. All tests were conducted at p<0.05. Results: Average sitting/lying time was 9hrs 29mins on a weekday (range 5hrs 52mins to 12hrs 55mins) and 8hrs 59mins (range 4hrs, 07mins to 14hrs, 40mins) on a weekend day. There was a main effect for weekday sitting/lying time on total anxiety and depression (HADS) and mental health and vitality (SF-12). Planned contrasts identified individuals in the low sitting/lying group had lower anxiety and depression and higher mental health and vitality scores than individuals in the medium or high group. No difference was found between individuals in the medium or high sitting/lying group. No main effects were found for weekend sitting/lying. Conclusion: Lower weekday sitting/lying time (below 8 hours/day) is associated with better mental health and quality of life. These findings add to the growing body of evidence reporting the detrimental effects of sedentary behavior on health and provide further justification for interventions to reduce sedentary time.