The theory that women incur less muscle damage than men after strenuous exercise has been exploded by a major new study which suggests the opposite: far from being protected against exercise-induced damage, women seem to be more severely affected, with a relatively reduced range of motion which persists for at least a week afterwards.
Most previous studies in this area have relied on indirect - and unreliable - markers of tissue damage, particularly the muscle protein creatine kinase, and have used small sample sizes and inappropriate exercise tests. The current study is the first to evaluate changes in muscle function in women and men in response to an exercise damage protocol.

A large sample of 83 women and 82 men performed a bout of eccentric exercise of the elbow flexors consisting of 70 maximal repetitions. Isometric strength, resting elbow angle and muscle soreness were measured before exercise, immediately afterwards and then daily for seven days.

The results were as follows:

* Muscle soreness peaked at 32-48 hours post exercise for both groups, with no significant difference between men and women;
* Both groups experienced a significant and similar loss of strength after exercise, with a similar rate of recovery;
* Men and women showed a similar loss in range of motion up to 48 hours post exercise, but the women revealed a more pronounced loss at 72 hours, which was still apparent at the end of the week.

'The cause of this difference is unclear,' say the researchers. 'Moreover, the mechanism driving the well-documented decrease in range of motion is not known.' However the finding is compatible with the theory that loss in range of motion is caused by changes in connective tissue, since women are more prone than men to connective tissue diseases. 'if connective tissue is more susceptible to injury in women, this may have contributed to the more pronounced muscle shortening and reduction in the elbow angle. However, it should be noted that the difference in loss of range of motion between men and women was small.'

J Sports Sci 2000,18,229-236