Abstract
OBJECTIVES: We examined the extent to which changes in worker health, as measured by health checkup items, were associated with increased intensity of leisure-time physical activity (LTPA) after controlling for individual time-invariant attributes. METHODS: We used panel data from two to four waves of a Japanese occupational cohort survey, focusing on 30,206 observations of 10,106 individuals (7,669 men and 2,437 women) aged 18-76 years. We estimated first-difference and mean-centered fixed effects models to examine how changes in 10 health checkup items were associated with changes in LTPA intensity. We considered four LTPA intensity levels (none, low, moderate, and vigorous), based on self-reported assessments. RESULTS: For men, low-density lipoprotein cholesterol levels, glycated hemoglobin levels, body mass index, and waist circumference improved when LTPA intensity was increased even at a low level, whereas triglyceride, high-density lipoprotein cholesterol, and fasting blood glucose levels improved when LTPA intensity was increased to moderate or vigorous levels. Blood pressure (both systolic and diastolic) and total cholesterol levels were only modestly responsive to changes in LTPA intensity. For women, blood pressure (both systolic and diastolic) and waist circumference were negatively associated with LTPA intensity, whereas the other variables showed more modest effects. CONCLUSIONS: The results suggest that even low- to moderate-intensity LTPA can improve health checkup results; however, the lowest LTPA intensity associated with improvement in health depends on health-risk factors as well as gender.