Repetitive Head Impact Exposure Does Not Affect Postural Control in Early to Middle-Aged Adults
Katie Hunzinger is a postdoctoral researcher working under Dr. Doug Wiebe and Dr. Andrea Schneider. She completed her undergraduate work in Kinesiolgoy at Northern Illinois University where she was a member of the Women’s Rugby team. She received her master's degree in Health and Exercise Science at Wake Forest University where she also received certification as a clinical exercise physiologist. She continued to work for Wake Forest on multiple randomized clinical trials before moving to Delaware to complete her PhD in Biomechanics & Movement Sciences at the University of Delaware under the mentorship of Dr. Tom Buckley and Dr. Buz Swanik. Her research focuses on concussion and subsequent musculoskeletal injury as well as the long-term outcomes of repetitive head impact exposure among male and female collision sport athletes. Outside of work she is a USA Rugby referee, a World Rugby Educator for referees and strength and conditioning, and CrossFit coach.
BACKGROUND AND AIM: Research on the long-term effects of repetitive head impacts (RHI) has been homogenous, utilizing self-report and subjective outcome measures. Further, samples have lacked generalizability and comparison, having included primarily collegiate or middle-aged males, with a history of playing high school or professional American football, despite evidence that females suffer worse outcomes to repetitive neurotrauma. Single task (ST) and dual task gait (DT) (i.e., gait with a cognitive task) are established measures of neurobehavioral function and known to be negatively impacted by neurotrauma and positively impacted by physical activity, providing an objective marker for neurophysiological health. Further, dual task cost (DTC), the change in performance in DT relative to ST provides insight on subtle gait and/or cognitive deficits. As such, a need exists to investigate the mid-life effects of RHI exposure using objective measures and multiple comparison groups and both sexes. Thus, the purpose of this study was to determine the effect of prolonged RHI exposure on measures of ST and DT gait among early-middle aged adults with varying levels of physical activity and RHI exposure.
METHODS: 113 adults (34.9 + 11.8 years, 53.0% female) representing four distinct groups participated in this study: those with no history of RHI who are not physically active (NON) or those who are physically active (NCA); and those who are physically active with a history of RHI through high-risk sports (HRS) or prolonged RHI exposure through rugby (RUG). Gait data was collected using inertial measurement unit measured level-overground ST and DT gait. DTC was calculated for all gait variables (double support, gait speed, stride length). Groups were compared using a one-way ANCOVA on all gait outcomes with known covariates included in the model (concussion history, height, age, contact/collision sport career duration—a measurement of lifetime RHI exposure, learning disability history, and sex).
RESULTS: A significant effect for group existed for ST gait speed (p=0.034) and ST double support (p=0.026), but there were no post-hoc observed group differences (p>0.05). There were no significant adjusted group differences for DT gait speed, ST and DT stride length, DT double support, or any DTC outcome (p>0.05).
CONCLUSIONS: When accounting for lifetime RHI exposure, physically active individuals with a history of RHI or prolonged RHI exposure through contact/collision sport participation (i.e., HRS and RUG) do not have worse gait performance as assessed by gait in early- to mid-adulthood than physically active individuals with no history of RHI exposure (NCA). These findings highlight the potential neuroprotective benefits of physical activity against the detrimental effects of RHI throughout ageing.
Keywordsconcussion; collision sports; gait
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