The Impact of Aerobic Exercise Training on Autonomic Function in Adolescent Sport‐Related Concussion
Authors: Harriss Alexandra , Woehrle Emilie , Barker Andrea , Moir M. Erin , Fischer Lisa , Fraser Douglas , Shoemaker J. Kevin 
Published: June 2021

IntroductionImpairments in autonomic function such as increased heart rate (HR) and reduced heart rate variability (HRV), have been observed in patients diagnosed with concussion. This may be indicative of cardiovascular and autonomic uncoupling. Aerobic exercise can help improve cardiac autonomic balance, and increase HRV. Accordingly, controlled aerobic exercise may help restore autonomic balance in adolescents diagnosed with a concussion.ObjectiveTo test the hypothesis that aerobic exercise rehabilitation can help restore autonomic functioning in adolescents diagnosed with a concussion.MethodsParticipants with a confirmed concussion diagnosis were recruited for this study. Participants were randomly allocated into one of two conditions, 1) Exercise (n=7, 14.2±1.7 years, 22.8±5.2 BMI) and; 2) Usual care (n=8, 14.6±1.6 years, 23.4±6.3 BMI). At baseline testing, each participant completed a five‐minute resting supine trial to record measures of the HRV signal. Following, participants performed a 10‐minute exertion test on a treadmill to symptom exacerbation, similar to previous work. The exercise group completed three additional days of monitored aerobic exercise at 80% HR of their symptom exacerbation. All exercise training was completed on a cycle ergometer within one‐week of baseline. The usual care group did not perform any exercise for one‐week. Follow‐up testing occurred one‐week post baseline. Main outcome measures for supine HRV were, root mean square of successive NN interval differences (RMSSD), standard deviation of successive NN interval differences (SDNN), total power, high frequency power, and low frequency power. HRV measures are reported as mean±standard deviation. The relative percent change between baseline and follow‐up were calculated for each outcome measure, and an independent samples t‐test was used to measure differences between conditions.ResultsCompared to study entry baseline levels, there was a significant main effect for exercise group RMSSD increased from baseline (44±21 ms) to follow‐up (50±22 ms) (p < 0.05, d = 1.3). However, RMSSD decreased for the usual care group from baseline (87±34 ms) to follow‐up (70±39). Similarly, was a statistically significant difference in SDNN scores (p < 0.05, d = 1.2) between conditions. SDNN increased in the exercise group from baseline (52.4±20.0 ms) to follow‐up (58.2±16.6 ms), and decreased in the usual care condition from baseline (80.5±22.3 ms) to follow‐up (67±24.7 ms) (p < 0.05, d = 1.2). There were no statistically significant differences for any frequency domain measures.ConclusionOur findings suggest monitored aerobic exercise training at 80% HR of symptom exacerbation may help restore autonomic imbalances associated with concussion injury in adolescents.Support or Funding InformationChildren's Health Research InstituteThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.