David R Howell1, Danielle L Hunt2, Stacey E Aaron2, Jason W Hamner2, William P Meehan2, Can Ozan Tan2. 1. From the Sports Medicine Center (D.R.H.), Children's Hospital Colorado, Aurora; Department of Orthopedics (D.R.H.), University of Colorado School of Medicine, Aurora; The Micheli Center for Sports Injury Prevention (D.R.H., D.L.H., W.P.M.), Waltham; Division of Sports Medicine (D.L.H., W.P.M.), Boston Children's Hospital; Cerebrovascular Research Laboratory (S.E.A., J.W.H., C.O.T.) and Cardiovascular Research Laboratory (J.W.H., C.O.T.), Spaulding Rehabilitation Hospital; Departments of Physical Medicine and Rehabilitation (S.E.A.) and Orthopedic Surgery and Pediatrics (W.P.M.), Harvard Medical School; and Division of Neuroradiology (C.O.T.), Massachusetts General Hospital, Boston. david.howell@cuanschutz.edu. 2. From the Sports Medicine Center (D.R.H.), Children's Hospital Colorado, Aurora; Department of Orthopedics (D.R.H.), University of Colorado School of Medicine, Aurora; The Micheli Center for Sports Injury Prevention (D.R.H., D.L.H., W.P.M.), Waltham; Division of Sports Medicine (D.L.H., W.P.M.), Boston Children's Hospital; Cerebrovascular Research Laboratory (S.E.A., J.W.H., C.O.T.) and Cardiovascular Research Laboratory (J.W.H., C.O.T.), Spaulding Rehabilitation Hospital; Departments of Physical Medicine and Rehabilitation (S.E.A.) and Orthopedic Surgery and Pediatrics (W.P.M.), Harvard Medical School; and Division of Neuroradiology (C.O.T.), Massachusetts General Hospital, Boston.
Abstract
BACKGROUND AND OBJECTIVES: Aerobic exercise has become a useful method to assist with postconcussion management. Exercise can exacerbate concussion symptoms even when symptoms are not apparent at rest. Few studies have examined the reasons for symptom exacerbation during exercise following a concussion. We had 2 primary objectives: (1) to delineate cardiopulmonary and cerebrovascular responses to exercise in adolescents and young adults with a concussion and healthy controls and (2) to determine the association between cerebrovascular responses and symptom burden. METHODS: We recruited participants with a recent concussion from a sport concussion clinic between September 1, 2018, and February 22, 2020. They were included if their concussion occurred <3 weeks before initial testing and if they were symptomatic at rest. Participants were excluded if they sustained a concussion in the past year (excluding index injury), reported history of neurologic disorders, or were using medications/devices that may alter neurologic function. Participants completed a progressive, symptom-limited, submaximal exercise protocol on a stationary bicycle. We assessed heart rate, blood pressure, fraction of end tidal CO2 (FETCO2), and middle cerebral artery blood flow velocity (CBF) and cerebrovascular function (vasoactivity and autoregulation) at seated rest and during exercise. RESULTS: We conducted 107 exercise tests (40 concussed, 37 healthy participants initially; 30 concussed at follow-up). Concussed participants were tested initially (mean 17.6 ± 2.2 [SD] years of age; 55% female; mean 12.5 ± 4.7 days postconcussion) and again 8 weeks later (mean 73.3 ± 9.5 days postconcussion). Control participants (mean 18.3 ± 2.4 years; 62% female) were tested once. FETCO2 increased throughout the exercise protocol as heart rate increased, reached a plateau, and declined at higher exercise intensities. CO2 explained >25% of the variation in resting CBF (R 2 > 0.25; p < 0.01) in most (73% individuals). Within the concussion group, resting symptom severity and the heart rate at which FETCO2 reached a plateau explained ∼2/3s of variation in exercise-induced symptom exacerbation (R 2 = 0.65; FETCO2 β = -1.210 ± 0.517 [SE], p < 0.05). There was a moderate, statistically significant relationship between cerebrovascular responses to CO2 at rest (cerebral vasoactivity) and cerebrovascular responses to exercise-induced changes in FETCO2 (R 2 = 0.13, p = 0.01). DISCUSSION: The arterial CO2 response and symptom exacerbation relationship during postconcussion aerobic exercise may be mediated by increased sensitivity of cerebral vasculature to exercise-related increase in CO2.
BACKGROUND AND OBJECTIVES: Aerobic exercise has become a useful method to assist with postconcussion management. Exercise can exacerbate concussion symptoms even when symptoms are not apparent at rest. Few studies have examined the reasons for symptom exacerbation during exercise following a concussion. We had 2 primary objectives: (1) to delineate cardiopulmonary and cerebrovascular responses to exercise in adolescents and young adults with a concussion and healthy controls and (2) to determine the association between cerebrovascular responses and symptom burden. METHODS: We recruited participants with a recent concussion from a sport concussion clinic between September 1, 2018, and February 22, 2020. They were included if their concussion occurred <3 weeks before initial testing and if they were symptomatic at rest. Participants were excluded if they sustained a concussion in the past year (excluding index injury), reported history of neurologic disorders, or were using medications/devices that may alter neurologic function. Participants completed a progressive, symptom-limited, submaximal exercise protocol on a stationary bicycle. We assessed heart rate, blood pressure, fraction of end tidal CO2 (FETCO2), and middle cerebral artery blood flow velocity (CBF) and cerebrovascular function (vasoactivity and autoregulation) at seated rest and during exercise. RESULTS: We conducted 107 exercise tests (40 concussed, 37 healthy participants initially; 30 concussed at follow-up). Concussed participants were tested initially (mean 17.6 ± 2.2 [SD] years of age; 55% female; mean 12.5 ± 4.7 days postconcussion) and again 8 weeks later (mean 73.3 ± 9.5 days postconcussion). Control participants (mean 18.3 ± 2.4 years; 62% female) were tested once. FETCO2 increased throughout the exercise protocol as heart rate increased, reached a plateau, and declined at higher exercise intensities. CO2 explained >25% of the variation in resting CBF (R 2 > 0.25; p < 0.01) in most (73% individuals). Within the concussion group, resting symptom severity and the heart rate at which FETCO2 reached a plateau explained ∼2/3s of variation in exercise-induced symptom exacerbation (R 2 = 0.65; FETCO2 β = -1.210 ± 0.517 [SE], p < 0.05). There was a moderate, statistically significant relationship between cerebrovascular responses to CO2 at rest (cerebral vasoactivity) and cerebrovascular responses to exercise-induced changes in FETCO2 (R 2 = 0.13, p = 0.01). DISCUSSION: The arterial CO2 response and symptom exacerbation relationship during postconcussion aerobic exercise may be mediated by increased sensitivity of cerebral vasculature to exercise-related increase in CO2.
Authors: Paul McCrory; Willem Meeuwisse; Jiří Dvořák; Mark Aubry; Julian Bailes; Steven Broglio; Robert C Cantu; David Cassidy; Ruben J Echemendia; Rudy J Castellani; Gavin A Davis; Richard Ellenbogen; Carolyn Emery; Lars Engebretsen; Nina Feddermann-Demont; Christopher C Giza; Kevin M Guskiewicz; Stanley Herring; Grant L Iverson; Karen M Johnston; James Kissick; Jeffrey Kutcher; John J Leddy; David Maddocks; Michael Makdissi; Geoff T Manley; Michael McCrea; William P Meehan; Shinji Nagahiro; Jon Patricios; Margot Putukian; Kathryn J Schneider; Allen Sills; Charles H Tator; Michael Turner; Pieter E Vos Journal: Br J Sports Med Date: 2017-04-26 Impact factor: 13.800
Authors: Kimberly G Harmon; James R Clugston; Katherine Dec; Brian Hainline; Stanley Herring; Shawn F Kane; Anthony P Kontos; John J Leddy; Michael McCrea; Sourav K Poddar; Margot Putukian; Julie C Wilson; William O Roberts Journal: Br J Sports Med Date: 2019-02 Impact factor: 13.800
Authors: John J Leddy; Mohammad N Haider; Michael J Ellis; Rebekah Mannix; Scott R Darling; Michael S Freitas; Heidi N Suffoletto; Jeff Leiter; Dean M Cordingley; Barry Willer Journal: JAMA Pediatr Date: 2019-04-01 Impact factor: 16.193
Authors: David R Howell; Danielle L Hunt; Stacey E Aaron; William P Meehan; Can Ozan Tan Journal: Am J Sports Med Date: 2021-04-15 Impact factor: 7.010
Authors: Mohammad N Haider; John J Leddy; Charles G Wilber; Kaitlin B Viera; Itai Bezherano; Kimberly J Wilkins; Jeffrey C Miecznikowski; Barry S Willer Journal: Front Neurol Date: 2019-04-24 Impact factor: 4.003