The effect of sex and localised fatigue on triceps surae musculoarticular stiffness.

PURPOSE: The main purpose of this study was to investigate the influence of fatigue on musculoarticular stiffness (MAS) of the ankle joint across sexes.

METHODS

Twenty-seven males and 26 females participated in the study. After baseline assessment of MAS and related variables, localised fatigue was induced in triceps surae using the standing heel-rise test during which the subjects were instructed to lift and drop the heel at a frequency of 0.5 Hz. When subjects were unable to continue due to exhaustion the test was terminated and another MAS test was performed soon after.

RESULTS

Significant higher triceps surae MAS was found in men compared to women (p < .01). MAS decreased (p < .01) between pre- and post-fatigue on average from 18.0 to 17.0 KN m-1 and from 14.5 to 13.9 KN m-1 in men and women, respectively. Percentage changes revealed, however, that in relative terms the changes in all the variables evaluated were similar (p > .01) between sexes, with MAS less than 5%.

CONCLUSION

Despite the sex-related differences at baseline, fatigue seems to affect biomechanical properties of the ankle joint similarly in men and women.