Abstract
Safely advising a sports related concussion (SRC) patient though their recovery presents risks to the clinician, coach, and most importantly, to the athlete affected. The current consensus holds that there is insufficient evidence to advise against beginning exercise before the patient is asymptomatic at rest. What remains unclear is whether there is any effect on return to play (RTP) times, or whether the risks of forcing an active person to remain sedentary for days to weeks (e.g. increased musculoskeletal injury risk, musculoskeletal and cardio-metabolic deconditioning) are outweighed by the risks of premature return to exercise (e.g. delayed or exacerbated symptoms). Gaps in understanding also exist around the diagnostic and prognostic uses of olfactory dysfunction, exercise intolerance, and cerebrovascular measures in the context of SRC.
In this feasibility study, concussed athletes (n=17) were randomised to an early return to high-intensity exercise or advice based on the current ACC recovery guidelines. The main outcome measurement was time to medical clearance. Both protocols involved an initial follow-up with a Sport and Exercise Physician (SEP) 24-72 hours post-injury. At baseline and recovery, all patients underwent the Combined Olfactory Test (COT), followed by a Buffalo Concussion Treadmill Test (BCTT) with concurrent middle cerebral artery velocity (MCAv) measurement. Patients were followed until deemed by the SEP to be medically clear to return to full sport participation. A further control group of non-injured athletes (n=18) were recruited to undergo the same testing procedures two weeks apart.
Patients randomised to the early return to high-intensity exercise protocol recovered in 34 ± 8 days, compared with 40 ± 22 days for patients following the ACC-based guidelines (p = 0.58). Compared to non-injured controls (20.7 ± 3.8 min), concussion patients exhibited a significantly shorter time to BCTT completion (12.3 ± 5.3 min) at session one (p = <0.01). This recovered to a time (20 ± 3.6 min) comparable to controls (22.2 ± 2.8 min) at session two (p = 0.16). A mixed three-way ANOVA revealed a significant main effect of Group (p = 0.02), whereby the non-injured control group showed a larger exercise-induced increase in MCAv during the BCTT (p = 0.02). This effect persisted throughout the post-test rest period (p = 0.01) while MCAv declined each Minute (p = <0.01) back toward baseline. No two- or three-way interactions between Group, Session, or Minute were evident. Olfactory threshold scores increased significantly from the early injury phase during recovery in concussion patients, compared to non-injured controls (p = 0.05). Participants’ number of previous concussions showed no relation to their COT scores (p = 0.92).
Despite not being powered to detect differences between follow-up protocols, the results from this study may support an early return to physical exercise before a patient is asymptomatic. The present work provides a methodology that could be implemented on a larger scale to support its current findings, to improve access to good SRC care, and to further the understanding of SRC pathophysiology.