Fatigue-Induced Alterations of Static and Dynamic Postural Control in Athletes With a History of Ankle Sprain

Context:

Sensorimotor control is impaired after ankle injury and in fatigued conditions. However, little is known about fatigue-induced alterations of postural control in athletes who have experienced an ankle sprain in the past.

Objective:

To investigate the effect of fatiguing exercise on static and dynamic balance abilities in athletes who have successfully returned to preinjury levels of sport activity after an ankle sprain.

Design:

Cohort study.

Setting:

University sport science research laboratory.

Patients or Other Participants:

30 active athletes, 14 with a previous severe ankle sprain (return to sport activity 6–36 months before study entry; no residual symptoms or subjective instability) and 16 uninjured controls.

Intervention(s):

Fatiguing treadmill running in 2 experimental sessions to assess dependent measures.

Main Outcome Measure(s):

Center-of-pressure sway velocity in single-legged stance and time to stabilization (TTS) after a unilateral jump-landing task (session 1) and maximum reach distance in the Star Excursion Balance Test (SEBT) (session 2) were assessed before and immediately after a fatiguing treadmill exercise. A 2-factorial linear mixed model was specified for each of the main outcomes, and effect sizes (ESs) were calculated as Cohen d.

Results:

In the unfatigued condition, between-groups differences existed only for the anterior-posterior TTS (P = .05, ES = 0.39). Group-by-fatigue interactions were found for mean SEBT (P = .03, ES = 0.43) and anterior-posterior TTS (P = .02, ES = 0.48). Prefatigue versus postfatigue SEBT and TTS differences were greater in previously injured athletes, whereas static sway velocity increased similarly in both groups.

Conclusions:

Fatiguing running significantly affected static and dynamic postural control in participants with a history of ankle sprain. Fatigue-induced alterations of dynamic postural control were greater in athletes with a previous ankle sprain. Thus, even after successful return to competition, ongoing deficits in sensorimotor control may contribute to the enhanced ankle reinjury risk.Key Words: sensorimotor control, neuromuscular activity, copers, balance, time to stabilization, Star Excursion Balance Test

Key Points

• When athletes were tested in the unfatigued state, only minimal differences in postural control were detected between athletes who had fully recovered from an ankle sprain and uninjured controls.
• Injured participants experienced larger fatigue-induced alterations of dynamic postural control than healthy controls.
• Persistent sensorimotor control deficits in recovered athletes might remain undetected in the unfatigued state.

Ankle sprains are the most common game-related injuries in team ball-sport athletes,¹ and are often associated with decreases in sensorimotor control, including proprioception (reduced joint position sense and kinesthesia), muscular strength, and balance performance (static and dynamic postural control). These alterations have been reported in individuals after acute ankle sprain^2,3 and in those with chronic ankle instability (CAI).^2,3 Along with additional complaints, such as swelling, pain, or episodes of “giving way,” sensorimotor deficits persist even years after injury.^4,5 Consequently, sensorimotor impairments associated with lower extremity injuries may contribute to performance impairments⁶ and increase the reinjury risk.⁷ Athletes who successfully return to high-level sports activities and report normal function without persistent complaints have previously been defined as copers.⁸ However, recent studies suggest that even though functional performance and self-reported disability in ankle-sprain copers are similar to those in individuals who have never sustained an ankle sprain,⁸ sensorimotor control might still be affected.^9,10The incidence of match injuries in soccer players increases toward the end of both halves,¹¹ suggesting that physical fatigue might play an important role in injury-related sensorimotor control changes. This concept is supported by a number of studies examining sensorimotor alterations after fatiguing exercise in healthy, uninjured participants; among the observed changes were reduced muscle strength and activity,¹² and altered proprioception¹³ and kinematics.¹⁴ Additionally, static postural control was assessed in most of these studies, showing an increase in postural sway due to localized fatigue of the ankle,¹⁵ knee, and hip¹⁶ muscles that can persist up to 10 minutes after exercise ends.¹⁷ Comparable results have been shown for fatiguing multijoint exercises¹⁷ and whole-body fatigue.¹⁸ Authors of only 2 studies have investigated the effects of fatiguing exercises on dynamic measures of postural control in healthy individuals¹⁹ and participants with CAI²⁰; however, because of different study populations and testing modalities, the effects remain uncertain.The findings described above suggest that long-term impairment of sensorimotor control exists after an ankle sprain and may even be present in those who do not develop persistent functional impairments and successfully return to preinjury levels of sport activity. To our knowledge, only 1 study²⁰ specifically investigated the effect of exercise-induced fatigue on participants with a previous ankle injury. Based on the findings of Gribble et al,²⁰ we hypothesize that these impairments are small under regular conditions but could expose athletes to an increased injury risk when they physically fatigue during intensive exercise.Therefore, the aim of our study was to investigate fatigue-induced alterations of static and dynamic postural control in a sample of ankle sprain copers and to compare the effects with those of uninjured controls. We proposed that changes in postural control due to fatigue would be more substantial in previously injured participants than in controls.