Comparing the Effects of Peroneal Muscle Fatigue and Cyclic Loading on Ankle Neuromuscular Control During Lateral-Hop Landing.

CONTEXT

Cyclic movements and muscle fatigue may result in musculoskeletal injuries by inducing changes in neuromuscular control. Ankle frontal-plane neuromuscular control has rarely been studied in spite of its importance.

OBJECTIVE

To compare the effects of peroneal muscle fatigue and a cyclic passive-inversion (CPI) protocol on ankle neuromuscular control during a lateral hop.

DESIGN

Quasi-experimental, repeated measures.

SETTING

University laboratory.

PARTICIPANTS

22 recreationally active, healthy men with no history of ankle sprain or giving way.

INTERVENTIONS

Participants performed a lateral hop before and after 2 interventions on a Biodex dynamometer. They were randomly assigned to intervention order and interventions were 1 wk apart. A passive intervention included 40 CPIs at 5°/s through 80% of maximum range of motion, and a fatigue intervention involved an isometric eversion at 40% of the maximal voluntary isometric contraction until the torque decreased to 50% of its initial value.

MAIN OUTCOME MEASURES

Median frequency of the peroneus longus during the fatigue protocol, energy absorption by the viscoelastic tissues during the CPI protocol, and feedforward onset and reaction time of the peroneus longus during landing.

RESULTS

A significant fall in median frequency (P < .05) and a significant decrease in energy absorption (P < .05) confirmed fatigue and a change in viscoelastic behavior, respectively. There was a significant main effect of condition on feedforward onset and reaction time (P < .05). No significant main effect of intervention or intervention × condition interaction was noted (P > .05). There was a significant difference between pre- and postintervention measures (P < .0125), but no significant difference was found between postintervention measures (P > .0125).

CONCLUSIONS

Both fatigue and the CPI may similarly impair ankle neuromuscular control. Thus, in prolonged sports competitions and exercises, the ankle may be injured due to either fatigue or changes in the biomechanical properties of the viscoelastic tissues.