The Effects of Subconcussive Impacts on Postural Stability

Context: The effects of concussions on postural stability, both acutely and chronically, have been well studied and noted. However, whether subconcussive impacts lead to these same impairments has not been heavily investigated.

Objectives: The primary purpose of this study was to examine the effects of subconcussive impacts on postural stability in NCAA Division I football athletes. We hypothesized that both the subconcussive (SUBC) group and the control (CONT) group would show declines in postural stability following a single fall season. We also hypothesized that there would be no significant differences between SUBC and CONT from preseason to postseason for Balance Error Scoring System total score and Approximate Entropy (ApEn) values. The secondary purpose was to predict deficits in postural stability based on cumulative linear acceleration, cumulative rotational acceleration, total number of impacts, and Head Injury Criterion (HIC). We hypothesized that the total number of impacts and cumulative linear acceleration would predict significant changes in postural stability.

Design: This was a prospective longitudinal study. Setting: The Georgia Southern University Biomechanics Laboratory.

Participants: 15 NCAA Division 1 collegiate football players were instrumented with the Head Impact Telemetry System (HITS) and 13 non-contact athletes with a fall season were recruited for control participants.

Intervention: The 2014 fall football season.

Results: No clinically significant deficits in postural stability were measured over the course of a single season. There was an increase in ApEn in the anteroposterior direction for left leg stance in both groups and in the mediolateral direction for double leg stance in SUBC over time.

Conclusion: The results of this study show no deficits across a single athletic season. However, caution should still be taken as there is literature supporting late-life detriments due to brain trauma.

Keywords: Subconcussive; Head Impact Telemetry System; postural stability; static stance; BESS; gait; dual task; approximate entropy

Year	Entry
1999	Powell JW, Barber-Foss KD. Traumatic brain injury in high school athletes. JAMA. September 8, 1999;282(10):958-963.
2003	McCrea M, Guskiewicz KM, Marshall SW, Barr W, Randolph C, Cantu RC, Onate JA, Yang J, Kelly JP. Acute effects and recovery time following concussion in collegiate football players: the NCAA concussion study. JAMA. November 19, 2003;290(19):2556-2563.
2009	McKee AC, Cantu RC, Nowinski CJ, Hedley-Whyte ET, Gavett BE, Budson AE, Santini VE, Lee H-S, Kubilus CA, Stern RA. Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury. J Neuropathol & Exp Neurol. July 2009;68(7):709-735.
1998	Cantu RC. Second-impact syndrome. Clin Sports Med. January 1998;17(1):37-44.
2001	Giza CC, Hovda DA. The neurometabolic cascade of concussion. J Athl Train. September 2001;36(3):228-235.
2011	Guskiewicz KM, Mihalik JP. Biomechanics of sport concussion: quest for the elusive injury threshold. Exerc Sport Sci Rev. January 2011;39(1):4-11.
2006	Brolinson PG, Manoogian S, McNeely D, Goforth M, Greenwald R, Duma S. Analysis of linear head accelerations from collegiate football impacts. Curr Sports Med Rep. February 2006;5(1):23-28.
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2007	Guskiewicz KM, Marshall SW, Bailes J, McCrea M, Harding HP Jr, Mattihews A, Mihalik JR, Cantu RC. Recurrent concussion and risk of depression in retired professional football players. Med Sci Sports Exer. June 2007;39(6):903-909.
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2005	Guskiewicz KM, Marshall SW, Bailes J, McCrea M, Cantu RC, Randolph C, Jordan BD. Association between recurrent concussion and late-life cognitive impairment in retired professional football players. Neurosurgery. October 2005;57(4):719-724.
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2003	Pellman EJ, Viano DC, Tucker A, Casson IR, Waeckerle JF. Concussion in professional football: reconstruction of game impacts and injuries. Neurosurgery. October 2003;53(4):799-814.
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Year

Entry

1999

Powell JW, Barber-Foss KD. Traumatic brain injury in high school athletes. JAMA. September 8, 1999;282(10):958-963.

2003

McCrea M, Guskiewicz KM, Marshall SW, Barr W, Randolph C, Cantu RC, Onate JA, Yang J, Kelly JP. Acute effects and recovery time following concussion in collegiate football players: the NCAA concussion study. JAMA. November 19, 2003;290(19):2556-2563.

2009

McKee AC, Cantu RC, Nowinski CJ, Hedley-Whyte ET, Gavett BE, Budson AE, Santini VE, Lee H-S, Kubilus CA, Stern RA. Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury. J Neuropathol & Exp Neurol. July 2009;68(7):709-735.

1998

Cantu RC. Second-impact syndrome. Clin Sports Med. January 1998;17(1):37-44.

2001

Giza CC, Hovda DA. The neurometabolic cascade of concussion. J Athl Train. September 2001;36(3):228-235.