Effects of Acute Fatigue of the Tibialis Anterior Due to a Weight-Bearing Muscle Activity on the Ankle Joint Position Sense in Healthy Subjects

Joint position sense (JPS) is comprised of sensory input from several sources, including skin, joint capsule/ligaments, and muscular receptors. If the muscle receptors play a leading role in detecting joint position awareness, then muscle fatigue might yield a declination in JPS. The aim of this study was to evaluate if a sustained fatiguing contraction of the tibialis anterior (ankle dorsiflexor) could alter the ankle JPS. This was a cross-sectional study in which 40 healthy subjects (age, 23.9±2.3 years; height, 172.6±5.7 cm; weight, 67.8±4.7 kg) were recruited. Subjects were asked to recognize 2 pre-recognized positions (10° in dorsiflexion (DF) and 21° in plantarflexion (PF)) for 2 experimental conditions: normal and fatigued. Muscular fatigue was induced in the tibialis anterior of the dominant leg by using an isometric test. The average of the absolute angular error (AAE) deviations from the target positions of three trials were recorded as scores for both fatigue and non-fatigue conditions. There was significant decrease in subjects’ abilities to recognize active and passive repositioning of their ankle after a fatigue protocol (P=0.0001). The acuity of the ankle JPS is reduced subsequent to a fatigue protocol.