The effect of individually tailored sub-symptom threshold exercise prescription in adolescents with physiological post-concussion disorder: a multi-institutional randomized controlled trial

Principal Investigator(s) Schneider, Kathryn

The effect of individually tailored sub-symptom threshold exercise prescription in adolescents with physiological post-concussion disorder: a multi-institutional randomized controlled trial


Although the vast majority of individuals who sustain a sport-related concussion (SRC) will receive medical clearance to return to sport within 7-10 days, an important cohort of patients will experience symptoms that last longer than a month. According to the most recent consensus statement on concussion in sport (Berlin 2017), there is some preliminary evidence to support the use of closely monitored active rehabilitation involving controlled sub-symptom-threshold submaximal exercise for people who continue to experience ongoing concussion related symptoms. However, the overall quality of the current literature has methodological limitations including low-level research designs, lack of a control intervention and inadequate measures to evaluate exercise time and intensity. Currently the optimal amount and intensity of exercise following concussion are not well defined. Thus, an adequately powered Randomized Controlled Trial (RCT) is needed to evaluate differences in recovery time when comparing moderate vs. light intensity individualized sub-symptom threshold exercise programs for adolescents with P-PCD.


The purpose of this RCT is to evaluate the efficacy of a moderate intensity (80% symptom tolerated max HR, Borg RPE 12-16) sub-symptom aerobic exercise prescription compared to a low level aerobic exercise group (60% symptom tolerated max HR, Borg RPE 7-11) on time to medical clearance to return to play in adolescents diagnosed with (P-PCD). Secondary objectives include: 1) To measure the adherence patterns of youth who are prescribed home exercise programs; 2) To monitor longitudinal changes in patient-reported symptoms through the use of the Pediatric Quality of Life (PedsQL) questionnaire (both child and parent for children 12 and under); 3) longitudinal changes in autonomic nervous system and cerebrovascular biomarkers throughout the stages of recovery. We hypothesize that the adolescents (aged 10-18) with P-PCD who spend a greater amount of time per day (minutes) in moderate physical activity will have earlier resolution of symptoms and be medically cleared to return to sport than individuals who engage in light intensity exercise.


A multi-institutional RCT will include two study sites (Pan Am Concussion Program, Winnipeg, Manitoba and Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Alberta). Adolescents (n=136, 68 from each study site) ages 10-18 years who are diagnosed with a sport-related concussion (SRC) and have ongoing symptoms for more than 10 days but less than 30 days will be recruited for participation in this study. Under the supervision of an exercise physiologist and physician, subjects will undergo the Buffalo Concussion Treadmill Testing (BCTT) which has been used previously to diagnose P-PCD. Participants diagnosed with P-PCD will then be randomized to either a moderate intensity (80% of maximal heart rate achieved during treadmill testing) or a low intensity (60%) aerobic exercise intervention. Both groups will be instructed to perform their respective aerobic exercise program the following day after completing an initial diagnostic treadmill test. Participants will be instructed to exercise at their prescribed intensity for a maximum of 30 minutes a day (5-minute warm-up, 20 minutes of aerobic exercise at prescribed subsymptom intensity, 5-minute cool down), 4-5 days a week. All participants will be asked to wear an Actigraph activity monitor to evaluate adherence to exercise regimens, and enable us to monitor the type and total amount of daily activity and daily caloric expenditure. Participants will be asked to fill out their daily 24-hour activity logs, weekly exercise tracker handouts and Actigraph monitor log whenever they take off the device for whatever reason (shower, swimming etc.).  Participants will attend weekly physician appointments to be evaluated for the possibility to initiate the return to play protocol. The following outcomes will be assessed every two weeks: Graded treadmill test to symptom threshold (to calculate new exercise intensity targets), and record scores on the SCAT5 and PedsQL. Once individuals are asymptomatic at rest and with daily activity, they will begin the standardized return to play protocol. If the protocol is completed successfully the participant will be re-examined for the possibility to become medically cleared to return to sport. At medical clearance the individuals will cease the intervention and all measures will be repeated. Patients will be managed medically according to the Concussion in Sport Return-to-Play guidelines. The primary outcome will be medical clearance to return to sport, defined as asymptomatic a rest, completed all steps of the return to play (RTP) protocol with no recurrence of symptoms, return to school full time without accommodations, no other clinical findings suggesting an inability to RTP.


Results would provide important insight into an emerging targeted treatment option for those with persistent physiological PCD but with no cervical or vestibular manifestations.


Funding has been obtained from CTRC with partnership funding from the SIPRC and Vi Riddell Pediatric Research Program at the U of C.  Ethics has been approved at U of M and is pending at U of C.