Exercise is Medicine for Concussion

Abstract

Sport-related concussion (SRC) is a physiological brain injury that produces cerebral and systemic effects, including exercise intolerance. Exercise intolerance after concussion is believed to be the result of autonomic nervous system (ANS) dysfunction. Ventilation is inappropriately low for the level of exercise intensity, raising arterial carbon dioxide (PaCO2) levels. Elevated PaCO2 increases cerebral blood flow (CBF) out of proportion to exercise intensity, which is associated with symptoms that limit exercise performance. Thus, elevated exercise PaCO2 may signal incomplete recovery from SRC. This article reviews recent observational and experimental data and presents the evidence that subthreshold aerobic exercise normalizes the cerebrovascular physiological dysfunction and is "medicine" for patients with concussion and persistent postconcussive symptoms (PPCS). It discusses the systematic evaluation of exercise tolerance after concussion using the Buffalo Concussion Treadmill Test (BCTT) and reviews the utility of the Buffalo Concussion Bike Test (BCBT), the data from which are used to establish an individualized heart rate "dose" of subthreshold exercise to safely speed recovery, which also may work in the acute recovery phase after SRC with the potential to reduce the incidence of PPCS. Evaluation and treatment approaches based on the physiology of concussion suggest that exercise is medicine for concussion, potentially adding a new dimension to concussion care to help safely speed recovery and prevent PPCS in some patients.

Pre-frontal Cortex Oxygenation Changes During Aerobic Exercise in Elite Athletes Experiencing Sport-Related Concussion

“…(1) that acute, short duration mild-to-intense exercise testing (HR = 110 bpm-170 bpm) can be performed safely in the days (D2, D4, D7) immediately following the diagnosis of concussion; and (2) that physiological measures can be easily collected and can be used to add to our understanding of the pathophysiological effects of concussion. This has important implications for treatment strategies, as current research suggests that sport-related concussion or mTBI is a physiological brain injury (McCrory et al, 2017;Leddy et al, 2018), and that concussion testing can potentially differentiate the type of mTBI (Ellis et al, 2015). Furthermore, our data support recent reports that physical exercise can be used safely when assessing recently concussed athletes within the first week post-injury in a controlled laboratory environment (Leddy et al, 2016a(Leddy et al, , 2017Haider et al, 2019).…”

“…To our knowledge this is the first study to systematically evaluate the physiological effects of repeated exercise tests using mild-to-intense exercise intensity (HR∼ 110-170 bpm) performed within 2-days (D2) after the medical diagnosis of sport-related concussion in high-performance athletes. Based on the growing body of literature in this area, moderate-to-intense exercise testing can be performed in concussed athletes safely, but most studies were performed more than a week after injury Ellis et al, 2015;Hinds et al, 2016;Leddy et al, 2016bLeddy et al, , 2018Haider et al, 2019;Morissette et al, 2019). Using an evidence-based approach, similar to our study, Leddy et al (2011Leddy et al ( , 2017 developed the Buffalo Concussion Treadmill and Bike Tests to specifically evaluate symptom limitations in post-concussion syndrome (PCS) patients and showed that concussed athletes assessed on average of 33 weeks (6-36 weeks) post-injury could reliably differentiate physiological dysfunction and quantify exercise capacity in PCS patients.…”

“…This research has added to our understanding of the pathophysiological changes that occur following a concussion (Len et al, 2011(Len et al, , 2013Giza and Hovda, 2014;Bishop and Neary, 2017;Bishop et al, 2017b;Worts et al, 2019), and has also provided a greater understanding of how we can apply exercise safely as a treatment strategy. Thus, it appears that evidence supports the therapeutic benefits of mildto-moderate intensity physical exercise (Kozlowski, 2014;Hinds et al, 2016;Leddy et al, 2016aLeddy et al, ,b, 2018 and that prolonged rest may be detrimental during acute recovery post-concussion Thomas et al, 2015;Buckley et al, 2016;Wells et al, 2016).…”

American Medical Society for Sports Medicine position statement on concussion in sport

“…A formal symptom-limited aerobic exercise programme has been shown to be safe and improve resolution of persistent symptoms compared with controls and should be considered in athletes with symptoms lasting longer than expected 78–80. The Buffalo Concussion Exercise Treatment Protocol, a progressive subsymptom threshold aerobic exercise programme based on systematically establishing the level of exercise tolerance on the Buffalo Concussion Treadmill Test, is the most studied controlled exercise programme 81. It is ideal for those with persistent postconcussive symptoms to be evaluated by a provider or multidisciplinary team with expertise in complicated concussion management.…”

Pediatric Post‐Traumatic Headache and Implications for Return to Sport: A Narrative Review

“…Current practice has shifted to support subsymptom‐level exercise after 24‐48 hours of rest and active rehabilitation if there is delayed recovery, although the optimal timing following injury for initiation of exercise remains unknown 2,31,68 . Safety and efficacy of early exercise has been previously demonstrated with no long‐term adverse effects attributed to transient symptoms exacerbation that may occur during post‐injury exercise 73‐77 …”