Exploring the provocation of postconcussion-like symptoms in response to a standardised exercise protocol incorporating a cognitive task

Abstract

Safely returning an athlete back to sport following a concussion is a challenging task for sports medicine practitioners. To facilitate safe management practices, best practice guidelines published from the most recent Concussion in Sport group’s consensus and agreement meetings included a progressive stepwise return to play (RTP) exercise protocol to assist the clinician. Although this stepwise progressive RTP protocol imitates fundamental aspects of sporting performance by including a basic progressive exercise regimen, the exact parameters of these exercise protocols are only loosely defined. The evaluation of baseline symptoms and the monitoring of their response to exercise and cognitive demands are integral to the understanding and development of RTP guidelines for concussion. This thesis explored the role of exercise alone, and in combination with two separate cognitive tasks (Paced Auditory Serial Addition Task and the electronic game Tetris), related to the cognitive function of working memory in provoking postconcussion-like symptoms in non-concussed individuals.

A single cohort repeated measures cross-over randomised design was employed where 36 participants (aged 21.9 ± 2.8 years) without a history of a recent concussion were assessed with three submaximal exercise based protocols, namely: exercise alone (SMEP), exercise with the Paced Auditory Serial Addition Task (SMEP+P) and exercise with Tetris (SMEP+T). Each exercise protocol involved three (five-minute) progressive stages of stationary cycling in predefined target heart rate (THR) zones at submaximal levels. During the SMEP+P and SMEP+T sessions, the cognitive tasks were administered before the exercise protocol and during the last two-minutes of each incremental stage. For the SMEP condition, no cognitive tasks were administered. At each session, the primary outcome measure (self-reported symptoms) was administered before (PRE), one-minute (POST-1) and 15-minutes (POST-2) after the exercise intervention. Exercise related variables such as heart rate, rate of perceived exertion, and cycling cadence were monitored throughout the protocol and the participants’ performance on the cognitive tasks were also documented.

A repeated measures analysis of variance of the total number of symptoms (TNS) reported on the Sport Concussion Assessment Tool 2 post-concussion symptom scale indicated a significant main effect over time (p < .001), no main effect between conditions (p = .371) and a non-significant time x condition interaction (p = .444). Post-hoc pairwise comparisons confirmed a significant increase in symptom scores in response to all three exercise protocols (p < .001) and symptom resolution over a 15-minute rest period (p < .001). No significant differences were detected between PRE and POST-2 (p = 1.000). A similar trend was observed for the other symptom variables analysed.

The three variations of the submaximal exercise protocol studied here provoked postconcussion-like symptoms in non-concussed individuals. The administration of a cognitive task together with a standardised exercise protocol did not have an additional impact on the provocation of postconcussion-like symptoms. These findings have implications for modelling future RTP protocols and the standardisation of rehabilitation strategies for sports-related concussions.