The effects of body composition changes to observed improvements in cardiopulmonary parameters after exercise training with cardiac rehabilitation

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 (pkVo(2)), 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 pkVo(2) was corrected for LBM (pkVo(2) 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). pkVo(2) increased 16% from 16.0+/-4.1 to 18.9+/-4.8 ml/kg/min (p<0.0001), and pkVo(2) 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 pkVo(2) or 12% of the increase in pkVo(2) 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 pkVo(2) lean should be used by investigators to assess the singular effects of exercise conditioning alone.