Importance Despite lower baseline fitness levels, women in cardiac rehabilitation (CR) do not typically improve peak aerobic exercise capacity (defined as peak oxygen uptake [peak Vo2]) compared with men in CR.
Objective To evaluate the effect of high-intensity interval training (HIIT) and intensive lower extremity resistance training (RT) compared with standard moderate intensity continuous training (MCT) on peak Vo2 among women in CR.
Design, Setting, and Participants This randomized clinical trial conducted from July 2017 to February 2020 included women from a community-based cardiac rehabilitation program affiliated with a university hospital in Vermont. A total of 56 women (mean [SD] age, 65  years; range 43-98 years) participating in CR enrolled in the study.
Interventions MCT (70% to 85% of peak heart rate [HR]) with moderate intensive RT or HIIT (90% to 95% of peak HR) along with higher-intensity lower extremity RT 3 times per week over 12 weeks.
Main Outcomes and Measures The primary outcome was the between-group difference in change in peak Vo2 (L/min) from baseline to 12 weeks.
Results Peak Vo2 increased to a greater degree in the HIIT group (+23%) than in the control group (+7%) (mean [SD] increase, 0.3 [0.2] L/min vs 0.1 [0.2] L/min; P = .03). Similarly, the change in leg strength was greater in the HIIT-RT group compared with the control group (mean [SD] increase, 15.3 [0.3] kg vs 6.4 [1.1] kg; P = .004).
Conclusions and Relevance An exercise protocol combining HIIT and intensive lower extremity RT enhanced exercise training response for women in CR compared with standard CR exercise training. Women randomized to HIIT experienced significantly greater improvements in both peak Vo2 and leg strength during CR.
Trial Registration ClinicalTrials.gov Identifier: NCT03438968