Abstract
Background: The safe return to play (RTP) following a sport concussion is a challenge to sports medicine practitioners. Recent international consensus has established a progressive stepwise RTP rehabilitation protocol as part of the comprehensive Sports Concussion Assessment Tool (SCAT/SCAT2). However the exercise parameters have not been specified in detail nor has the protocol been subjected to scientific scrutiny. The main purpose of this thesis was to investigate elements of the SCAT2 RTP rehabilitation protocol by developing and validating a controlled exercise assessment tool incorporating a cognitive component. Central to this thesis was the measurement of symptoms resulting from a concussion and their provocation with exercise. This thesis conducted four individual projects resulting in the development of a clinically validated assessment tool.
Methods and results: Study 1 employed a systematic review methodology to review the self-reported symptom scales/checklists used in the acute sports concussion environment and to report their psychometric properties. This review identified six core symptom scales/checklists with their 14 derivatives. The scales/checklists had a broad range of symptom items with limited information on their psychometric properties. The postconcussion symptom scale included in the SCAT/SCAT2 was chosen as the primary outcome measure for this thesis.
Study 2 was conducted with 60 non-concussed recreational athletes to explore the selfreported symptoms provoked by moderate and high intensity levels of exercise. The study concluded that high intensity exercise can significantly (p < 0.001) increase the summed symptom scores immediately after exercise and the effect persisted even after 15-minutes of rest (p < 0.001). However moderate intensity exercise did not significantly (p > 0.05) elevate the symptom scores.
Study 3 included 30 non-concussed athletes to develop and standardize an exercise tool incorporating both physiological (e.g. exercise) and cognitive loads (e.g. simple reaction time) and resulted in the development of the Otago postconcussion RTP symptom based exercise assessment tool (Otago PC-RTP tool). The exercise tool was sub-maximal with three stages (based on heart rate zones) of 5 minute progressions, during the last 2 minutes of which the cognitive load task was introduced.
Study 4 investigated the validity of the Otago PC-RTP tool with 15 concussed (asymptomatic at rest) and 30 non-concussed athletes. A significant difference in summed symptom scores was observed between control and concussed groups immediately following (p < 0.001) and 15-minutes after (p < 0.001) conclusion of the exercise. A standard test termination criterion was followed. The concussed participants were invited for a second visit (mean interval of 2.3 days) if they had demonstrated an increase in symptom scores (n = 12) or stopped (n = 3) the exercise tool. The symptom scores were significantly elevated immediately following exercise (p <0.001) at second visit (n = 10) and were significantly reduced between the visits (p <0.001).
Conclusion: This thesis resulted in the development of a clinically valid, graded sub-maximal, symptom based assessment exercise tool that can assist sports medicine professionals involved in the management and care of the athletes following a concussion. The Otago PC-RTP tool modeled the SCAT2 RTP rehabilitation protocol.