Key result
Leisure sedentary time over 8 hours daily linked to ~24% higher MI risk.
Why the study?
The associations between leisure-related sedentary time, physical activity, and myocardial infarction incidence including its subtypes were not comprehensively investigated.
Does prolonged leisure-related sedentary time increase the incidence of myocardial infarction, and do higher durations of physical activity or sleep reduce this risk in adults free of prior MI?
Cohort (n=475,874)
Yes
Does prolonged leisure-related sedentary time increase the incidence of myocardial infarction, and do higher durations of physical activity or sleep reduce this risk in adults free of prior MI?
Prolonged leisure-related sedentary time is independently associated with an increased risk of incident myocardial infarction, while reallocating sedentary time to physical activity or sleep modestly lowers this risk.
Answers are grounded in this paper and cite their sources.
Hypothesis-generating for sedentary reduction in primary MI prevention; prospective trials needed before practice change.
Objectives: This study aimed to comprehensively investigate the associations between leisure-related sedentary time, physical activity (PA), and the incidence of myocardial infarction (MI) and its subtypes. Methods: This cohort study included 475,874 individuals free of MI at baseline. Daily behavioral data-including leisure-related sedentary time, PA, and sleep duration-along with baseline demographic characteristics were collected. Three multivariable-adjusted Cox proportional hazards models were constructed to assess the association between leisure-related sedentary time and incident MI. Additionally, a mutually adjusted Cox model incorporating all four behaviors simultaneously was used to estimate hazard ratios for inter-behavior comparisons via coefficient contrasts, evaluating whether higher PA or sleep durations, independent of other measured behaviors, were associated with reduced MI risk. Results: Compared with the reference group, individuals with leisure-related sedentary time exceeding 4 h per day had an increased risk of MI and its subtypes after full multivariable adjustment. Mutually adjusted analyses demonstrated inverse associations with MI risk across all behaviors. Coefficient contrasts indicated that a 60-min higher duration of sleep, LPA, or MVPA-holding other measured behaviors constant-corresponded to hazard ratios of 0.967 (95% CI: 0.954-0.980) for sleep, 0.987 (95% CI: 0.964-1.011) for LPA, and 0.974 (95% CI: 0.953-0.995) for MVPA. Consistent patterns were observed for 30-min and 15-min contrasts, with estimated risk reductions ranging from approximately 1-6% across all comparisons. Conclusion: Prolonged leisure-related sedentary time is associated with an increased risk of MI, STEMI, and NSTEMI. Independent of other daily behaviors, higher durations of PA and sleep are inversely associated with MI incidence, with benefits evident even at modest (15-30 min) differences in daily duration.
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Sun et al. (2026) conducted a cohort in Myocardial infarction (n=475,874). Leisure-related sedentary time >8 hours/day vs. Leisure-related sedentary time ≤2 hours/day was evaluated on Myocardial infarction incidence (HR 1.24, 95% CI 1.15-1.34, p=<0.001). Prolonged leisure-related sedentary time exceeding 8 hours per day was associated with a 24% increased risk of incident myocardial infarction (HR 1.24) compared to 2 hours or less per day.
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