Sex differences in physical and mental health following high-intensity interval training in adults with cardiovascular disease who completed cardiac rehabilitation

This pre-post study examined sex-differences in peak aerobic power ((V)over dotO(2peak)) and physical-and mental-health outcomes in adults with cardiovascular disease who completed high-intensity interval training (HIIT)-based cardiac rehabilitation. HIIT consisted of 25 minutes of alternating higher-(4x4 minutes 85-95% heart rate peak (HRpeak)) and lower (3x3 minutes 60-70% HRpeak) intensity intervals twice weekly for 10 weeks. (V)over dotO(2peak) estimated from a graded exercise test using the American College of Sports Medicine equation, body mass index (BMI), waist circumference, blood pressure, blood biomarkers and anxiety and depression were assessed at baseline and follow-up. Linear mixed-effects models for repeated measures were performed to examine differences over time between sexes. Of 140 participants (mean +/- standard deviation: 58 +/- 9 years), 40 were female. Improvements in (V)over dotO(2peak) did not differ between sexes (interaction: p = 0.273, females: 28.4 +/- 6.4 to 30.9 +/- 7.6; males: 34.3 +/- 6.3 to 37.4 +/- 6.0 mL/kg/min). None of the time by sex interactions were significant. Significant main effects of time showed reductions in waist circumference, triglycerides, low-density lipoprotein (LDL), total cholesterol (TC)/high-density lipoprotein (HDL) and anxiety, and increases in (V)over dotO(2peak) and HDL from baseline to follow-up. Significant main effects of sex revealed smaller (V)over dotO(2peak), BMI and waist circumference, and higher LDL, TC and HDL in females than males. HIIT led to similar improvements in estimated (V)over dotO(2peak) (females: 8.8%, males: 9.0%) and additional health outcomes between sexes. Novelty: HIIT-based cardiac rehabilitation led to similar improvements in estimated (V)over dotO(2peak) and other physical and mental health outcomes between sexes. The number of sessions attended was high (>70%) and did not differ by sex. Both sexes showed good compliance with the exercise protocol (HR target).