Concussion History and Heart Rate Variability During Bouts of Acute Stress

Abstract

Context: Following a sports-related concussion, many athletes experience persisting neurophysiological alterations. These alterations may be absent at rest but emerge during moments of physiological stress. Unnoticed and untreated neurophysiological dysfunction may negatively impact long-term neurological health in adolescent athletes as they are at a critical point in development. Objective: To assess cardio-autonomic functioning in athletes with and without a history of concussion by quantifying measures of heart rate variability (HRV) during times of physical and mental exertion. Design: Case-control study. Setting: Research laboratory Patients or Other Participants: Thirty-four male midget-AAA hockey players were separated into those with (n = 16, age = 16.1 ± 1 years, BMI = 23.3 ± 1.8) and those without (n = 18, age = 16.0 ±1 years, BMI = 23.6 ± 2.5) a history of concussion. Intervention(s): All athletes completed a series of HRV recording sessions: 1) at rest; 2) while completing a cognitive task at rest; and 3) while completing a cognitive task after a bout of submaximal aerobic exercise. Main Outcome Measure(s): Time-domain measures of HRV; mean NN interval (NN), standard deviation of NN interval (SDNN), and root mean square of successive differences (RMSSD) were quantified for each assessment. Results: Analyses revealed no demographic differences between groups. No between-group differences in HRV at rest, were observed. However, during completion of the cognitive task at rest and following aerobic exercise, athletes with a history of concussion demonstrated significantly higher SDNN (63.2 ± 4.1 vs. 78.1 ± 4.3; 65.2 ± 3.8 vs 71.2 ± 4.3, p = 0.046) and RMSSD (59.0 ± 5.6 vs. 75.8 ± 6.0; 59.0 ± 5.2 vs. 74.0 ± 5.5, p = 0.035). Conclusion: The results suggest concussive injuries may result in long-term cardio-autonomic dysfunction. Furthermore, these deficits may not be present at rest but may be triggered by physiological stress.

History of concussion and lowered heart rate variability at rest beyond symptom recovery: a systematic review and meta-analysis

“…One thing that was not specified in the inclusion criteria for this analysis was the number of prior concussions in the TBI groups. Although three of the studies included the number of prior concussions in the demographics ( 25 , 26 , 28 ), only one of the included studies conducted an analysis to stratify the groups by number of prior concussions, to find out if the deficits to HRV last longer or are more prominent as the number of prior concussions increases. They conclude that those with a history of two or more concussion may be susceptible to long-term or even permanent alterations in ANS neurotransmission, and that a history of multiple concussions may negatively impact recovery of the ANS after a bout of exercise ( 25 ).…”

“…The included studies did combat this potential factor by ensuring there was no significant age difference between the TBI and control groups, so any underlying influence that age would have on the experiment would be evenly distributed between the two groups. When it comes to the age difference between studies, one study had an age range of 18–59 ( 24 ), while others focused on young male athletes aged around 16 ( 25 , 26 ). Finding a more homogenous population in age and gender would help minimize any such differences.…”

Concussion burden and later‐life cardiovascular risk factors in former professional American‐style football players

“…The pathophysiologic link between antecedent head injury and CVD factors represents an area of active investigation. While the mechanisms delineating this phenomenon remain incompletely understood, several biologically plausible explanations including neuroinflammation, 37 disruption of the bidirectional brain–gut axis, 38 hypopituitarism, 39 and autonomic nervous system dysfunction have been proposed 40,41 . Targeted investigation of how head injuries lead to the development CVD risk factors and subsequent adverse CVD outcomes represents an area of important area for future work.…”

“…While the mechanisms delineating this phenomenon remain incompletely understood, several biologically plausible explanations including neuroinflammation, 37 disruption of the bidirectional brain–gut axis, 38 hypopituitarism, 39 and autonomic nervous system dysfunction have been proposed. 40 , 41 Targeted investigation of how head injuries lead to the development CVD risk factors and subsequent adverse CVD outcomes represents an area of important area for future work. Unexpectedly, this study also found that BMI was not associated with hyperlipidemia and diabetes in multivariable models.…”