Investigating Persistent Sympathovagal Dysregulation Following a Complex Dual Task in Concussed Athletes

TL;DR

This study explores autonomic responses in athletes with a history of concussion during complex dual tasks, finding that a cognitive task alone reveals autonomic changes not seen in combined tasks.

Contribution

The study introduces a novel use of dual tasks to investigate autonomic dysregulation in concussed athletes using heart rate variability.

Findings

Concussed athletes showed increased HRV after a cognitive task compared to rest.

Combining cognitive and motor tasks eliminated the autonomic response seen in cognitive tasks alone.

Aerobic exercise did not affect the autonomic response to dual tasks in concussed athletes.

Abstract

Background/Objectives: Dual tasks are increasingly being employed in research on concussion, since they provide a somewhat more realistic representation of the demands athletes face on the field. While single cognitive and motor tasks have revealed persisting autonomic alterations in concussed athletes, the unique autonomic response required by a dual task remains unexplored in this population. The purpose of this study was to evaluate autonomic responses in asymptomatic athletes with a history of concussion (m = 5.46 months ± 2.00) following a complex dual task. Methods: Heart rate variability (HRV), a biomarker of autonomic regulation, was measured in 34 athletes (16 concussed, 18 controls) aged 17 to 24. HRV data were collected using the Polar H10 chest belt. Five-minute segments were extracted under four conditions: rest, following a cognitive task (switch task), after a dual task combining both motor and cognitive components, and after the same dual task preceded by 20 min of aerobic exercise. A series of 4 × 2 mixed-design ANOVAs were conducted to assess the differences between the conditions and groups. Results: The results indicated a significant increase in a global marker of HRV (i.e., the standard deviation of normal-to-normal intervals (SDNN)) following the switch task compared to rest (p = 0.014) only in concussed participants. These results suggest that the switch task may stimulate frontal regions and promote a parasympathetic response, as reflected by the rise in HRV. Notably, the effect of the switch task disappeared when combined with the motor component of the dual task, whether it was preceded by aerobic exercise or not. Conclusions: The dual task results indicate potential competing mechanisms between the motor and cognitive components of the task, which future studies using similar protocols should consider. Meanwhile, the switch task appears sufficiently demanding to reveal autonomic alterations, which, when measured through HRV, may constitute a relevant clinical tool for assessing athletes’ readiness to return to sport and academic study.

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