Impact of Body Composition on Peak Oxygen Uptake After Cardiac Rehabilitation

ABSTRACT Background Peak oxygen uptake (VO 2 peak), standardized to total body mass (ml/kg/min) is a predictor of morbidity and mortality in cardiovascular disease patients. However, subsets of individuals undergoing exercise based cardiac rehabilitation (CR) show no improvement or reduction in VO 2 peak despite improvement in other functional measures. Our aim is to assess the influence of CR on lean mass, and the effect of body composition compared to total body mass changes on peak VO 2 following CR. Methods This pre-post intervention study included adults >18 years old who completed CR between 2015-2022 at Mayo Clinic, Rochester. All patients completed both dual energy X-ray absorptiometry (DXA) and cardiopulmonary exercise testing (CPET) for measurement of body composition (total mass and lean mass) and VO 2 peak pre-post CR. Improvement in VO 2 peak was defined as positive percent change. Descriptive statistics, paired t-tests, univariable and multivariable linear regression modeling were performed. Results Of 140 subjects, 19.3% were female and 96.4% White with a mean (SD) age of 63 (12.5) years, BMI of 30.2 (5.82), and a mean of 27.1 (11.7) completed number CR sessions. Pre-post CR total body mass loss was −1.28 (3.18) kg and lean mass gain was 0.84 (2.86) kg. All changes were statistically significant (p<0.05). Pre-post CR VO 2 peak in absolute units had a percent change increase of 6.52 (13.1) mL/min, relative (corrected for total body mass) increase of 8.24 (13.6) mL/kg/min, and relative to lean mass increase of 5.73 (13.4) mL/lean-kg/min. Pre-post percentage of subjects with a positive change in peak VO 2 in absolute units was 70%, relative was 75%, and relative to lean mass was 67.9%. Multivariable regression showed statistical significance in peak VO 2 percent change for all units when adjusted for pre-CR peak VO 2 . Conclusions Our findings demonstrate significant increases in lean mass and VO 2 peak following CR, with larger improvements reflected in units adjusted for total mass compared to other methods. These data suggest the reporting methodology for change in VO 2 peak following CR impact overall results. CLINICAL PERSPECTIVE Published studies have reported that subsets of patients undergoing exercise-based cardiac rehabilitation (CR) may show no improvement or even reduction in peak oxygen uptake (VO 2 peak), a predictor of mortality in individuals with cardiovascular disease, which may be partly influenced by body composition. This pre-post intervention study of 140 adult patients who completed CR demonstrated significant increases in lean mass and VO 2 peak following CR across the cohort while suggesting the reporting methodology for change in VO 2 peak impacts overall results. Our findings could imply that a proportion of patients continue to demonstrate additional abnormalities that inhibit improvement in VO 2 peak independent of body composition alterations, partially explaining why a subset of patients have a lack of positive change in VO 2 peak. Significant predictors for reduced VO 2 peak improvement following CR may include female sex and pre-CR VO 2 peak. Despite CR significantly improving lean body mass, the ability to utilize that mass to generate useful oxidative metabolism could be limited and may require a longer duration of CR to maximize oxidative metabolic efficiency and improve patient outcomes following acute cardiac events.