Interactive effects of physical activity and sarcopenia on incident ischemic heart disease: Results from a nation-wide cohort study.

Background And Aims: Lack of physical activity (PA) and sarcopenia is a known risk factors for ischemic heart disease (IHD). However, considering their coexistence in the middle-aged and elderly population, the interaction of these two factors remains uncertain. Here, we investigated the interactive effects of PA and sarcopenia on IHD.

Methods: We extracted 344,688 participants free of IHD at baseline from the UK Biobank. PA was classified into low, moderate, and high according to the International Physical Activity Questionnaire. Sarcopenia was identified in accordance with the European Working Group on Sarcopenia in Older People 2. Cox proportional hazard models were applied to estimate the effect of PA and sarcopenia on incident IHD and its subtypes. We also used objective PA data measured by wrist-worn devices to repeat these analyses.

Results: Over a median follow-up of 11.7 years, 24,809 (7.2%) participants developed incident IHD. Lack of PA was associated with a higher risk of IHD after adjusting for potential confounders. The hazard ratio (HR) was 1.09 (95% CI: 1.05-1.13) for individuals without sarcopenia and 1.29 (95% CI: 1.17-1.42) for those with sarcopenia. Regarding the joint effect, the combination of low PA and sarcopenia was associated with the highest risk of IHD, with an HR of 1.54 (95% CI: 1.44-1.66), and both additive and multiplicative interactions were significant (RERI 0.27, 95% CI: 0.14-0.39, p-interaction <0.01). For subtypes of IHD, the interaction was pronounced in acute myocardial infarction and chronic ischemic heart disease.

Conclusions: These results suggest a synergistic interaction between lack of PA and sarcopenia on the risk of IHD. Findings from this study may help facilitate more effective primary prevention of IHD.