Study objective: To discriminate the effects of body fat reduction on improvements in peak aerobic capacity made following exercise training during cardiac rehabilitation.
Design: Observational, prospective study.
Setting: Outpatient cardiovascular health center at regional academic center.
Patient interventions: Peak oxygen uptake (pkVo2), percent body fat, lean body mass (LBM), and other anthropometric measures were assessed before and after a 3-month program of cardiac rehabilitation and exercise training in 500 consecutive cardiac patients following a major coronary event. Baseline pkl=V:o2 was corrected for LBM (pklV:o2 lean) and compared with posttraining values.
Results: Following exercise training, percent body fat decreased 5% from 26.2±8.0 to 24.8±7.5 (p<0.0001), and LBM increased 1% from 61.3±12.5 to 61.7±11.8 kg (p=0.02). pkVo2 increased 16% from 16.0 ±4.1 to 18.5±4.8 mL/kg/min (p<0.0001), and pkVo2 lean increased 13% from 21.7±5.3 to 24.6±6.0 mL/kg/min (p<0.0001). Isolating the effects of reduction in body fat, we discern that these changes contributed to 0.3 of the 2.5 mL/kg/min increase in pkVo2 or 12% of the increase in pkVo2 observed.
Conclusions: Changes in body composition, as a consequence of dietary and exercise modification, contribute to 12% of the "observed" improvement noted in weight-adjusted peak aerobic capacity following cardiac rehabilitation and exercise training. Changes in pkVo2 lean should be used by investigators to assess the singular effects of exercise conditioning alone.