Chest
Volume 113, Issue 3, March 1998, Pages 599-601
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Clinical Investigations: Exercise
The Effects of Body Composition Changes to Observed Improvements in Cardiopulmonary Parameters After Exercise Training With Cardiac Rehabilitation

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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 ( pkV˙o2), 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 pkV˙o2 was corrected for LBM ( pkV˙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). pkV˙o2 increased 16% from 16.0±4.1 to 18.5±4.8 mL/kg/min (p<0.0001), and pkV˙o2 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 pkV˙o2 or 12% of the increase in pkV˙o2 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 pkV˙o2 lean should be used by investigators to assess the singular effects of exercise conditioning alone.

Section snippets

Materials and Methods

We prospectively evaluated 500 consecutive patients 4 to 6 weeks following a major cardiac event (coronary bypass surgery, myocardial infarction, percutaneous coronary angioplasty) who were referred for cardiac rehabilitation at the Cardiovascular Health Center of Ochsner Medical Institutions. Patients participated in outpatient cardiac rehabilitation and exercise training that lasted 12 weeks and included 36 educational and exercise sessions. Each session consisted of approximately 10 min of

Results

The mean age of the cohort was 63±11 years, and 80% of the study population was male. The percent body fat was 26.2±8.0 at baseline and decreased to 24.8±7.5 (—5%; p<0.0001) following cardiac rehabilitation (Table 1). Although there was a modest 1% reduction in total weight (83.0±17.5 to 82.0±16.4 kg; p<0.0001) following the rehabilitation program, lean body mass (LBM) increased a modest 1% (61.3±12.5 to 61.7±11.8 kg; p=0.02). Weight-adjusted pkV˙o2 increased by 16% (16.0±4.1 to 18.5±4.8

Discussion

This investigation demonstrates that reduction in body fat contributes to the “observed” improvement in weight-adjusted pkV˙o2 following exercise conditioning programs, such as cardiac rehabilitation, thereby overestimating the true improvement present. Furthermore, although a training effect was clearly present, exercise conditioning alone was responsible for 88% of the improvement noted in weight-adjusted peak aerobic capacity.

Dietary modification of both fat, and when appropriate, total

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