Sunday, March 19, 2006

Exercise intensity and body composition

The aim of a new study was to compare the effect of two exercise training programs, one of low and one of high intensity, on body composition.
  • Group one: 4x week exercise on treadmill at 45% of V.O 2 max for three months, spending 370 calories per exercise session.
  • Group two: same frequency but greater intensity - 72% of V.O 2 max.
  • No dietary intervention


  • Body mass decreased significantly in both groups but more in the low-intensity than the high-intensity group.
  • The decrease in fat mass was significant in both groups, but not significantly different between them.
  • Fat-free mass (muscle) did not change significantly in either group, although the difference between groups tended to be significant.

In conclusion, exercise training at 45 % of V.O 2 max produced a higher weight loss than at 72 % of V.O 2 max and the higher intensity tended to maintain muscle, possibly, in part, through the smaller weight loss. Thus, both programs may prove useful in eliciting favourable changes depending on which target (weight loss or maintenance of muscle) is of higher priority.

Do both! Exercise at a lower intensity 3 days per week and a higher intensity 3 days per week. Remember, to burn the same number of calories, you'll have to exercise longer on the low intensity days. If there's no need to lose weight, it's probably still a good idea to back off the intensity to give you variety and to avoid injury.


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