Influence of Reallocating Time to Sedentary and Physical Activity on Cardiometabolic Risk Factors in Japanese Men

Abstract

Physical activity has been beneficially associated with cardiometabolic risk factors, whereas long sedentary time has been detrimentally associated with cardiometabolic risk factors. These associations are typically examined after adjusting for confounders. It would be best to consider a finite time interval while treating sedentary and physical activities as interdependent. PURPOSE: To examine the association between cardiometabolic risk factors, objectively measured sedentary time, and time allocated to light-intensity physical activity (LPA) or moderate- to vigorous-intensity physical activity (MVPA). METHODS: One hundred twenty-eight men (average age, 49.4 ± 9.2 years; average body mass index [BMI], 26.8 ± 3.7 kg/m2) wore triaxial accelerometers (Active style Pro, OMRON HEALTHCARE Co., Ltd.) on the hip for 2 consecutive weeks to assess sedentary time, LPA, and MVPA during waking hours (instructed to remove the device for swimming and bathing). The participants who obtained no less than 72 h of data, corresponding to a period of physical activity of ≥10 hours/day, with at least one valid weekend day, were included in the study. The association between BMI, waist circumference, blood pressure, high-density lipoprotein cholesterol level, triglyceride level, HbA1c level, and activity variables (30-min increments/day) was examined after adjusting for confounders, wear time, and activity variables using isotemporal substitution modeling. RESULTS: BMI, waist circumference, and triglyceride level were positively associated (P < 0.05) with sedentary time and less LPA. Diastolic blood pressure was negatively associated (P < 0.05) with LPA. High-density lipoprotein cholesterol level was positively associated (P < 0.05) with LPA and MVPA. Less sedentary time (−30 min/day) with more LPA (+30 min/day) was positively associated with BMI (β = −0.31 kg/m2; 95% confidence interval [CI], −0.59 to −0.04), waist circumference (β = −1.08 cm; 95% CI, −1.81 to −0.35), and diastolic blood pressure (β = −0.98 mmHg; 95% CI, −1.74 to −0.22). Less sedentary time (−30 min/day) with more MVPA (+30 min/day) was positively associated with triglyceride level (β = −26.99 mg/dl; 95% CI, −49.97 to −4.00). CONCLUSIONS: Reallocating sedentary time to LPA and MVPA may contribute to determining cardiometabolic risk factors.