- Both anaerobic and aerobic exercise protocols adversely affected postural control, as measured with the Balance Error Scoring System, sway velocity, and elliptical sway area.
- The effects of fatigue persisted for up to 13 minutes before postural control returned to baseline.
- Clinicians assessing an athlete with a suspected concussion should wait at least 13 minutes after activity stops before testing with the Balance Error Scoring System.
Interest in the proper management of sport-related mild traumatic brain injuries (TBIs) within the sports medicine community has increased in recent years. In the past, assessment of mild TBI relied heavily on subjective symptoms reported by the athlete.1
This practice can become dangerously problematic if an athlete withholds information in order to return to competition, leaving the clinician without a clear picture of the athlete's condition, including (but not limited to) mental status.1,2
The lack of objective and quantifiable information on which to base a return-to-play decision after a mild TBI poses a quandary for sports medicine clinicians. Thus, clinicians managing mild TBI have started including alternative means of identifying deficits after a suspected head injury, which may help to prevent premature return to competition and serious injury.3–,6
Postural control testing has been a very important component that allows clinicians to obtain an objective measure of mild TBI. Using force plate measures as a validity reference, researchers7
developed the Balance Error Scoring System (BESS), which is used on the sideline to measure an athlete's balance after a suspected mild TBI. Baseline scores for the BESS are established during preseason screenings and are taken at rest. However, sideline evaluations for mild TBI are most often undertaken during practice or competition, not at rest. Therefore, numerous extraneous factors, aside from the mild TBI, may influence postural control.8–,10
Fatigue has been shown to negatively affect postural control.2,11–,14
However, few authors have measured the effect of fatigue on the performance of the BESS. Crowell et al2
demonstrated decreased postural stability after an exercise protocol consisting of squat jumps, sprints, and treadmill running. Similarly, Wilkins et al9
found a decrease in postural stability as a result of a 7-station, 20-minute exercise protocol as measured by the BESS total error score. Although both of these groups investigated fatigue as a combined function of anaerobic and aerobic activity, they did not clearly delineate between the fatigue effects related to one versus the other.
Also, few authors have investigated the immediate recovery time after fatigue for postural control measures to return to baseline. The limited research available showed decreased postural stability immediately postexercise but no deficits as early as 20 minutes postexercise.15–,18
More importantly, these authors combined aerobic and anaerobic exercise into protocols lasting 20 minutes or longer. The recovery timeline may differ when an aerobic exercise protocol is compared with an anaerobic exercise protocol.
The aforementioned authors examined exercise protocols that were explicitly aerobic in nature. To our knowledge, the immediate effects of an anaerobic exercise protocol on postural control have yet to be established. In addition, the effects of fatigue induced by an anaerobic exercise protocol have not been compared with an aerobic exercise protocol.
Therefore, our primary purpose was to evaluate the effects of fatigue on postural control after anaerobic and aerobic exercise protocols in healthy, college-aged varsity athletes. A secondary purpose was to establish an immediate recovery time course from each exercise protocol over which the effects of fatigue lessened and postural control measures returned to baseline status. Although we hypothesized postural stability would decrease after each exercise protocol, we believed the deficits after the anaerobic protocol would be more pronounced than those after the aerobic protocol. Because force plate measures of postural control are more sensitive to fatigue-related and injury-related changes than the BESS is, we decided to include these measures as part of our research protocol to determine whether sensitive changes were identified by the BESS in these scenarios.