Relationship Between Exercise At Different Periods Of Time And Coronary Artery Disease In A Chinese Population

Purpose: Exercise leads to a lower risk of coronary artery disease(CAD). But whether exercise at different times of day has effect on CAD is still unclear. The present study is to investigate relationship between exercise at different times of day and angiography determined coronary atherosclerosis in a Chinese population.Methods and Results: The present study population consisted of 1129 consecutive patients who underwent coronary angiography(CAG) for the first time. Patients were divided into 2 groups(Non-CAD and CAD groups) according to the result of coronary angiography. We use a pre-designed questionnaire, the work-related activity, leisure-time activity, and exercise information was recorded in the form of self-reporting. Coronary artery disease(CAD) was defined as a stenosis >50% in the left main trunk or in the other major coronary arteries [left anterior descending coronary artery(LAD), left circumflex coronary artery(LCX) and right coronary artery(RCA)]. Information on intensity(none, low, moderate-high), duration(none, ≤ 30min/day, 30-60min/day, > 60min/day), frequency(none, ≤ 4day/wk, >4day/wk), starting age(none 、≤ 47 years, 48-53 years, 54-59 years, ≥ 60years), period of time [none, morning(5:00-8:00), forenoon(8:00-12:00), afternoon(15:00-18:00), evening(18:00-21:00)] and lifestyle were collected before CAG by trained interviewers. Exercise was associated with a reduced risk of CAD, with an odds ratio(OR) of 0.59(95% confidence interval, 0.46–0.77), after adjusting the established and potential confounders, with an adjusted OR of 0.48(95% CI, 0.35-0.67) compared with those who did not take any exercise. Compared to non-exercisers, the adjusted ORs were 0.57(0.40–0.82) for low intensity exercise and 0.34(0.22–0.52) for moderate-high exercise, with a statistically significant test for trend(P<0.002). Dose–response relationships were also observed for duration, frequency, and starting age of taking exercise. Further stratification analysis revealed that the protective effect of exercise were more significant in the afternoon and evening group than in the morning and forenoon group. The adjusted ORs of taking exercise in morning(5:00-8:00), forenoon(8:00-12:00), afternoon(15:00-18:00), evening(18:00-21:00) groups were 0.53(0.36-0.78), 0.51(0.27-0.96), 0.46(0.25-0.85), 0.43(0.28-0.66), respectively, when compared to non-exerciser, with a statistically significant test for trend(P<0.05).Conclusions: Exercise can decrease the risk of CAD, and exercising in the afternoon or evening may have more significant effects on the prevention of CAD than in other time of day.