Does the intensity of an exercise programme modulate body composition changes?

Area of Science:

• Exercise Physiology
• Sports Science
• Body Composition Analysis

Background:

• Exercise training is a key component of weight maintenance programs.
• The impact of exercise intensity on body composition changes, beyond total energy expenditure, requires further clarification.

Purpose of the Study:

• To compare the effects of two isoenergetic exercise training programs of differing intensities on body composition.
• To investigate whether exercise intensity influences weight loss and body mass components.

Main Methods:

• Fourteen healthy premenopausal untrained women were divided into two groups.
• Both groups underwent treadmill exercise training for three months, four times weekly, expending 1548 kJ (370 kcal) per session.
• One group exercised at 45% of maximal oxygen uptake (V(O2max)), while the other exercised at 72% of V(O2max).

Main Results:

• Body mass decreased significantly in both groups, with greater loss in the low-intensity group (3.3 kg) compared to the high-intensity group (1.9 kg).
• Fat mass decreased significantly in both groups, with no significant difference between them.
• Fat-free mass showed no significant change in either group, but a trend towards preservation was observed in the high-intensity group (p=0.058).

Conclusions:

• Exercise training at 45% of V(O2max) led to greater weight loss than at 72% of V(O2max) without dietary changes.
• Higher intensity exercise (72% V(O2max)) tended to better maintain fat-free mass, potentially due to the lower overall weight loss.
• Both low and high-intensity exercise programs can be beneficial for weight management, depending on the primary goal (weight loss vs. fat-free mass preservation).