Sex Differences in Cardiometabolic Health Indicators after HIIT in Patients with Coronary Artery Disease

Abstract

Purpose: Cardiorespiratory fitness (CRF) is an independent predictor of mortality, and females typically achieve smaller improvements in CRF than males after exercise-based cardiac rehabilitation. High-intensity interval training (HIIT) has been shown to produce superior improvements in CRF than traditional cardiac rehabilitation, but the sex differences are unknown. The purpose of this systematic review and meta-analysis was to evaluate sex differences for changes in CRF and cardiometabolic health indicators after HIIT in adults with coronary artery disease (CAD).

Methods and results: A systemic search of five electronic databases for studies examining the effect of HIIT on measured CRF and cardiometabolic health indicators in adults with CAD was performed. Data (published and unpublished) from 14 studies were included in the meta-analyses with approximately eightfold greater male than female participation (n = 836 vs n = 103). Males with CAD achieved a near-significant absolute improvement in CRF (mean difference [MD] = 1.07, 95% confidence interval [CI] = -0.08 to 2.23 mL·kg-1⋅min-1, P = 0.07) after HIIT when compared with control; there were insufficient data to conduct such an analysis in females. Significantly smaller improvements in CRF were experienced by females than males (MD = -1.10, 95% CI = -2.08 to -0.12 mL·kg-1⋅min-1, P = 0.03); there was no sex difference for the relative (percentage) change in CRF after HIIT. Females achieved significantly smaller reductions in body mass index (MD = -0.25, 95% CI = -0.03 to -0.47 kg·m-2, P = 0.02) and fasting blood glucose (MD = -0.38, 95% CI = -0.05 to -0.72, P = 0.03); no sex differences were observed for other cardiometabolic health indicators.

Conclusion: There are no sex differences for relative improvements in CRF after HIIT; however, females are greatly underrepresented in trials. Future studies should increase female participation and perform sex-based analyses to determine sex-specific outcomes following HIIT.