Balance control during gait in athletes and non-athletes following concussion
Introduction
Current concussion research has largely focused on cognitive neuropsychological testing as a means to assess recovery following a concussion. It has been suggested that athletic participation, particularly in contact sports, may have an adverse effect on performance in tests of cognitive function [1], [2], [3]. Downs and Abwender [1] examined the frequency of “heading” in soccer for ball control and propulsion, and found that length of a soccer career and high levels of play were related to poorer cognitive test performance. A similar finding was revealed by Rutherford et al. [3] when soccer and rugby athletes were examined. Killam et al. [2] examined cognitive function among non-concussed, recently concussed, and non-recently concussed contact and non-contact athletes and compared them to non-athletes. Their results suggested that participation in contact sports may produce cognitive impairments without diagnosed concussion.
While the use of neuropsychological evaluation has recently been advocated as the “cornerstone” of proper concussion management [4], all domains that may be impacted by brain injury are not assessed by this method. One such domain that has not frequently been investigated is post-concussion recovery of dynamic motor function. Previous work has examined recovery of static balance and revealed that participants with mild traumatic brain injury (MTBI) demonstrated impaired postural stability for 1–5 days following injury [4], [5], [6], [7]. However, Guskiewicz et al. [6] reported no relationship between concussion symptoms, performance on tests of cognitive function, and static postural stability. Johnson et al. [8] assessed post-injury symptoms and psychomotor performance of concussed athletes (mild brain injury) and matched controls over 10 days post-injury. They found the concussed subjects to exhibit significantly greater symptom scores than controls 1 day after injury, but no group differences were observed for the time to complete a psychomotor agility task. Data from Parker et al. [9] suggested that post-concussion recovery of motor function might be independent of cognitive recovery and that a longer recovery time may be needed for the resolution of more complex tasks.
Few data are available on the performance of dynamic motor tasks following concussion. Parker et al. [10], [11] introduced a new method of assessing concussion and recovery that focused on gait as a dynamic functional motor task during conditions of divided and undivided attention. They found that gait imbalance increased when concussed subjects were asked to walk while simultaneously performing a secondary cognitive task compared to walking without mental distraction. Gait imbalance, in the divided attention condition, was marked by greater sway and sway velocity of the whole body center of mass (COM) that were maintained for up to 28 days following injury.
Competitive sport activities present a venue in which head injuries are common [12]. Previous research on concussed athletes has shown that complex motor functions require a longer recovery period than cognitive tasks [10], [11], [13]. It has also been suggested that participation in contact sports may have a negative effect on cognitive function without the existence of a medically diagnosed concussion [3]. However, little data are available that compare concussed and non-concussed athletes and non-athletes on complex neuro-motor tasks. Therefore, the primary purpose of this study was to examine gait performance as well as COM motion in concussed and uninjured athletes and non-athletes.
It has been postulated that long-term participation in contact sports that expose athletes to repetitive, sub-concussive head trauma may compromise neuropsychological function [1], [2], [3], [14]. This suggests that chronic, relatively low-impact, as well as, acute high-impact head traumas may result in neurological impairment. Therefore, a secondary purpose of this study was to investigate the extent to which high- and low-impact sports participants differ in the recovery of gait stability following concussion.
Section snippets
Materials and methods
Fifty-six college-aged men and women served as subjects for this study. The subjects were categorized into four groups of equal number according to athletic and concussion status. The concussed groups consisted of NCAA Division I or University Club Sports athletes (CONC-A; n = 14) and non-athletes who engaged in no regular sports activities (CONC-NA; n = 14). The uninjured control groups consisted of NCAA Division I or University Club Sports athletes (NORM-A; n = 14) and non-athletes who engaged in
Results
The results revealed a significant interaction (p = 0.003) between task (single/dual) and testing day (2–28) for gait velocity. For all groups, the dual-task condition resulted in significantly slower GV compared to single-task on all days, and GV was significantly slower on day 2 than all other days for both tasks (Table 2). The gait velocity of athlete groups was slower than non-athlete groups in both task conditions for all testing days. During the single-task condition, the concussed and
Discussion
For the sagittal plane variables, the athletes displayed a slower gait velocity and shorter separation distance between the COM and COP than the non-athletes. In prior studies [20], [21], patients with traumatic brain injury with lasting complaints of gait imbalance were found to walk with a significantly reduced anterior COM velocity and displacement. A similar pattern of decreased gait velocity, increased sway, and sway velocity was found in concussed individuals, and these differences were
Conflict of interest
None.
Acknowledgements
This study was supported by the Centers for Disease Control and Prevention (R49/CCR021735 and CCR023203), which did not have a role in the design, collection, analysis or publication of the data. The authors gratefully acknowledge the assistance of Robert Catena in data collection.
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Current address: Department of Movement Science, Grand Valley State University, Allendale, MI 49401, USA.