Effects of fatigue due to contraction of evertor muscles on the ankle joint position sense in male soccer players.

BACKGROUND

The high incidence of ankle sprains that occur later in matches suggests that fatigue may contribute to altered neuromuscular control of the ankle. Moreover, deficits in ankle joint position sense (JPS) were seen in patients with a history of recurrent ankle sprains. It has been hypothesized that ankle sprains may be related to altered ankle JPS as a consequence of fatigue.

PURPOSE

To evaluate if fatiguing contractions of evertor muscles alter the ankle JPS.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six soccer players (age, 24.7 +/- 1.3 years; height, 183.7 +/- 8.2 cm; weight, 78.9 +/- 7.9 kg) were recruited. Subjects were asked to recognize 2 positions (15 degrees of inversion and maximal active inversion minus 5 degrees ) for 2 conditions: normal and fatigue. Muscular fatigue was induced in evertor muscles of the dominant leg by using isometric contractions. The average of the absolute and variable errors of 3 trials were recorded for both fatigue and nonfatigue conditions. A matched control group of 36 soccer players (age, 23.9 +/- 0.9 years; height, 181.2 +/- 6.9 cm; weight, 77.8 +/- 6.5 kg) was asked to recognize the same positions, before a soccer match and after 45 minutes of playing, and their same scores were recorded. Finally, results of the 2 groups were compared.

RESULTS

There was significant decrease in subjects' ability to recognize passive and active repositioning of their ankle after a fatigue protocol (P <.001). Passive and active JPS were reduced after playing (P <.001). There was no significant difference between 2 groups in the results of JPS before and after the intervention (P > .1).

CONCLUSION

The acuity of the ankle JPS is reduced subsequent to a fatigue protocol and after a soccer match.

CLINICAL RELEVANCE

Evaluation of athletes' ankle JPS before returning to physical activity may prevent further injuries.