Sport-Related Concussion and Exercise Intolerance

Concussion-related exercise intolerance is defined as the inability to exercise at or near to age-appropriate maximum heart rate (HR) due to exacerbation of concussion-related symptoms. It is hypothesized to result from damage to the Autonomic Nervous System interfering with normal cerebral blood flow regulation and is considered to be a physiological biomarker of sport-related concussion (SRC). Exercise tolerance can be safely assessed using standard exertion tests as soon as two days after concussive injury and has been shown to have prognostic utility when performed within 10 days of injury. The HR at symptom exacerbation, called the Heart Rate threshold (HRt), can be used to prescribe an individualized aerobic exercise prescription to treat SRC. Controlled, sub-symptom threshold aerobic exercise prescribed early after SRC has been shown to safely reduce recovery time and may prevent some from experiencing delayed recovery, which is called Persistent Post-Concussive Symptoms (PPCS). Before beginning the return-to-play protocol, in addition to reaching a baseline level of symptoms and having a normal physical examination, athletes must be able to demonstrate normal exercise tolerance, That is the ability to exercise to 85%-90% of their ageappropriate maximum HR without exacerbation of concussion symptoms. (C) 2022 Elsevier Inc. All rights reserved.