Interactions between the effects of exercise and weight loss on risk factors, cardiovascular haemodynamics and left ventricular structure in overweight subjects.

OBJECTIVE

To assess the individual and combined effects of exercise and weight loss on the cardiovascular risk factors and cardiac left ventricular structure and function in overweight individuals.

METHODS

A randomized, parallel-group, crossover study design was adopted. The following treatments were employed: exercise three times a week at 70% maximum work capacity for 30 min; dietary modification to achieve weight loss involving 4200 kj/day dietary restriction; and a combination of both exercise and dietary modification weight-loss programmes. Each subject was randomly assigned to one group only and was studied after a 12-week treatment and 12-week control period, performed in a random order. Thirty subjects entered the trial, 23 completing both treatment and control phases.

RESULTS

Body weight remained unchanged with exercise alone and fell significantly both with weight loss and with the combination. The corresponding effects on blood pressure were also significant. Exercising groups also showed a significant increase in maximal oxygen consumption and a reduction in heart rate. Serum cholesterol and triglycerides fell significantly only after the combination, whereas high-density lipoprotein-cholesterol increased with exercise, decreased with weight loss and did not change with the combination. Interventricular septum and posterior wall thickness measurements remained unchanged after 12 weeks' treatment in all groups. No significant changes occurred in left ventricular internal diastolic diameter, wall thickness:radius ratio or the heart rate corrected ratio of peak early diastolic filling velocity:peak late diastolic filling velocity. Left ventricular mass and mass indexed to body surface area were not changed in any group.

CONCLUSIONS

The results indicate that the effects of exercise and weight reduction on blood pressure are additive, although a positive interaction may exist with respect to lipids. Despite lowering blood pressure, exercise and weight loss had no effect on cardiac left ventricular structure or function in these overweight individuals.