Table 2.

Exertion Assessment Protocols

Author	Purpose and Study Design	Sample	Protocol Exertion Mode, Type, and Rationale	Protocol Intensity and Progression Parameters	Relevant Observed Measures	Relevant Results	Pertinent Study Limitations
Cordingley, 2016	Retrospective case series evaluating safety, clinical use, and patient outcomes	106 patients (46 M, 60 F); Mean age 15.1 years, range of 11–19 years SD 1.5 years; Median days from injury until initial testing 8 days (IQR 5–22 days)	Mode and Type: Treadmill with incremental progressions in treadmill grade (modified Balke protocol/Buffalo Concussion Treadmill Test)	-Speed of 3.2 miles per hour, 0% grade on treadmill. Grade increased by 1% per minute for the first 15 minutes, then increased .2 miles per hour every minute thereafter until exacerbation of symptoms or workload could not be maintained	-Physiologic measures -Adverse events	-No serious complications or adverse events -No persistent elevations in heart rate, blood pressure, or respiration rate	-The proportion of patients for whom test termination was due to symptom exacerbation vs exhaustion is unclear -It is also unclear if subgroups (e.g., those with vestibular or oculomotor impairments) had different responses or self-limiting behaviors leading to earlier termination of the tests
			Rationale: No specific rationale provided for mode, but protocol choice was noted as selected based on prior studies
DeMatteo, 2014	Cross-sectional case series study evaluating the Nintendo Wii games for assessing return to activity readiness	24 participants (14 M, 10 F); Mean age 14.9 years, range of 9–18 years, time since injury range of 1–12 months with a mean of 5.5 months and SD of 3.68 months	Mode and Type: 6 Wii Games of progressive intensity	-First Wii game selected for lowest complexity and effort based on difficulty, quantity of movements, and balance and exertion requirements -6 Wii games presented in increasing intensities with 3 minutes rest between each game	-Physiologic measures	-Wii Fit Basic Run had the highest mean post-game HR and mean calorie expenditure -Wii UPC running had the highest mean post respiration rate	-The workload and ability to do this systematically is unclear based on the design of this study -Symptom responses to exertion were not reported -Unclear if subgroups (e.g., those with vestibular or oculomotor impairments) had different responses or self-limiting behaviors due to these impairments -There was some loss to follow-up with only 37 of 54 participants responding at the 24-hour follow-up -The fitness level of the participants prior to injury was not reported nor controlled through study design -A relatively young and small sample with a wide range in time since injury
			Rationale: A rationale for Wii games for assessment was described as a way to assess functional mobility and exertion. No specific rationale was provided for the games selected or protocol specifically
DeMatteo, 2015	Case series of a single exercise testing bout with repeated measures of response to exertion and recovery from exertion	54 participants with recent mTBI (32 M, 22 F) Mean age of 14.8 years, SD of 2.3. Time from most recent injury range of .7–35.3 months with median of 4.1 months	Mode and Type: Cycle ergometer with incremental progressions in work rate (McMaster All-Out Progressive Continuous Cycling Test)	-Individualized starting work rate with fixed rotations per minute; cycling between 25–85 watts based on age, height, body mass, and level of fitness -Fixed increase in work rate every 2 minutes until exhaustion, dropping <50 rotations per minute, or concussion-like symptoms return	-Symptoms -Exertion duration -Physiologic measures	-63% of participants had symptoms during exertion testing -Number and severity of symptoms significantly affected perception of exertion at 50% of peak mechanical power -Both the number and severity of symptoms significantly improved over 24 hours for 56.8% of participants	-Time from injury and age had significant effect on symptom scores at baseline and after exertion -Participants were all relatively young -No direct comparison group
			Rationale: No specific rationale provided for mode or protocol selection
Gall, 2004a	Repeated measure cohort comparison study of 2 exercise testing bouts within 72 hours of being asymptomatic at rest and again 5 days later	14 hockey players with mTBI and 14 players without mTBI matched 1:1 by investigators, no report of sex of participants in sample, mean age of participants reported by cohorts	Mode and Type: Cycle ergometer with 10 minutes of steady-state cycling, followed by high intensity intervals	Low-moderate steady-state exercise at 80–90 rpm against a constant load of 1.5W/kg of body weight for 10 minutes. High intensity bouts: 40 seconds at 4.7 W/kg with a pedaling frequency of 90–100 rpm, followed by a 20 second free pedal (30 W), and then 20 second rest period - Test continued until the participant could no longer maintain the workload	-Symptoms -Number of high intensity exercise bouts completed -Physiologic measures	-No difference in number of high intensity bouts completed between cohort with concussion and matched controls -No difference in blood lactate levels between the groups -No difference was found in the symptoms reported between the groups -A subgroup of the cohort with concussion (those who missed playing time as a result of the concussion) exhibited a higher heart rate in the low-moderate exercise period and exhibited a greater rise in heart rate over the time -No significant differences between the groups were observed in blood lactate levels at rest or after exertion	-The sample size was relatively small and focused solely on athletes -Sex of participants was not reported, so it is unclear if this is generalizable across sexes
			Rationale: No specific rationale provided for mode or protocol selection
Gall, 2004b	Repeated measure cohort comparison study of 2 exercise testing bouts within 72 hours of being asymptomatic at rest and again 5 days later	14 hockey players with mTBI and 14 players without mTBI matched 1:1 by investigators, no report of sex of participants in sample, mean age of participants reported by cohorts	Mode and Type: Cycle ergometer with 10 minutes of steady-state cycling, followed by high intensity intervals	Low-moderate steady-state exercise at 80–90 rpm against a constant load of 1.5W/kg of body weight for 10 minutes. -High intensity bouts: 40 seconds at 4.7 W/kg with a pedaling frequency of 90–100 rpm, followed by a 20 second free pedal (30 W), and then 20 second rest period - Test continued until the participant could no longer maintain the workload	--Physiologic measures	-No difference in HR or heart rate variability metrics between the cohort with concussion and matched controls -HRV metrics revealed lower RR, LF and HF power during exercise for the cohort with concussion	-The sample size was relatively small and focused solely on athletes -Sex of participants was not reported, so it is unclear if this is generalizable across sexes
			Rationale: The authors noted that the protocol was designed to reflect high intensity intervals that often occur while playing ice hockey.
Grabowski, 2017	Retrospective case series evaluating the implementation, safety, and feasibility of multimodal impairment-based physical therapy (including vestibular therapy, manual therapy and exercise therapy for cervical and thoracic spine, and aerobic training)	25 patients (11 M/14 F) mean age of 15 years (range 12–20 years) following sport-related concussion with a mean of 41 days post-injury (range 21–228 days) prior to first visit	Mode and Type: Patient specific treadmill (modified Balke protocol/Buffalo Concussion Treadmill Test) vs cycle ergometer incremental increases in bike resistance	-Treadmill: initial speed of 3.3 mph with 0% grade. Grade was increased to 2.0% at start of second minute and increased by 1% for every minute thereafter until 15% was reached. If test continued beyond that point, speed was increased by .1 miles per hour each minute until exacerbation of symptoms or exhaustion -Cycle ergometer: Cadence was maintained on an electronically braked-cycle ergometer with initial resistance set at level 1 and increased by 1 level every minute until exacerbation of symptoms or exhaustion	-Symptoms -Symptom-free exercise duration -Maximum symptom-free heart rate -Instances of symptom exacerbation with exercise on two consecutive days	-88% of patients reported an improvement in symptom scores after intervention, with 24% reporting symptom-free state at end of the treatment -55% of patients who terminated exercise due to symptom exacerbation at initial session achieved a symptom-free maximal effort test by end of treatment -Mean duration of exercise was greater at the last exercise test compared to the initial baseline test -Two instances of minor symptom exacerbations were reported while performing cardiovascular exercise at home	-The sample size was relatively small and the nature of the study was retrospective -28% of the patients discontinued for reasons unrelated to safety or efficacy (e.g., non-compliance, insurance changes)—however, some showed improvement in symptom score and maximum symptom-free heart rate
			Rationale: The treadmill protocol was the default, with the cycle ergometer used according to patient preference and/or in the presence of significant vestibular symptoms in order to minimize head movement
Hinds, 2016	Case series and case-control comparisons using a repeated measure design investigating exercise assessment while symptomatic and after deemed recovered	40 athletes (23 M, 17 F) ages 12–18 years (mean 15.5 years) and comparison of 30 athletes without a history of recent concussion (18 M, 12 F)	Mode and Type: Treadmill: Incremental progressions in treadmill grade (modified Balke protocol/Buffalo Concussion Treadmill Test)	-Speed of 3.3 miles per hour, 0% grade on treadmill. Grade was increased by 1% per minute for the first 15 minutes, then increased .2 miles per hour every minute thereafter until exacerbation of symptoms or workload could not be maintained	-Physiologic measures -RPE	-Resting HR did not differ between bout while symptomatic and bout when recovered -HR was significantly lower when participants were symptomatic at the start of exercise but the relative increase in HR relative to increased intensity did not differ while symptomatic compared to when recovered -RPE was consistently rated higher for comparable work while symptomatic compared to when recovered -No differences in HR or relative change in HR or RPE with repeated administration for youth without a recent concussion	-The timing between the first and second testing sessions relative to the time since injury were unclear, however, the results allude to most of the testing taking place in the acute phase post-recovery -Participants were all relatively young
			Rationale: No specific rationale provided for mode, but protocol choice was noted as selected based on prior studies
Kozlowski, 2013	Case control comparisons for a single exercise bout comparing exercise tolerance for individuals with persistent postconcussion symptoms compared to a healthy control cohort	59 participants 34 injured (17 M, 17 F; mean age = 25.9 SD 10.9 years), 22 controls (11 M, 11 F; mean age = 23.3 SD 6.2 years)	Mode and Type: Treadmill Walking: Incremental progressions in treadmill grade (modified Balke protocol/Buffalo Concussion Treadmill Test)	Constant speed of 3.3 miles per hour, starting at 0% incline. After 1 minute, fixed 2% grade increase; after 2 minutes, fixed 1% grade increase each minute until speed could not be maintained, post-mTBI symptoms returned, or max of 21 minutes was reached	-Symptoms -Exertion duration -Physiologic measures	-No difference between groups in resting heart rate or blood pressure measures -Injured group demonstrated shorter test duration, lower max HR at test termination, lower max blood pressure at test termination, and a lower achieved workload -Systolic blood pressure was the only measure to show a sex effect within the injured cohort with males having higher blood pressure throughout the testing	-Convenience sample compared to historical dataset with a widespread of ages and days since injury
			Rationale: No specific rationale provided for mode or protocol selection
Kurowski, 2017	Randomized clinical trial investigating aerobic exercise training versus a stretching control group for a 6 week program	30 adolescents (13 M, 17 F ages 12–17 years between 4 – 16 weeks post-injury with 87% reporting regular participation in an organized sport; randomization was performed within stratified age and gender blocks	Mode and Type: Cycle ergometer with incremental progressions in intensity	Self-selected speed consistent with their personal Borg rate of perceived exertion of level 11 (fairly light pace) with fixed resistance at level 2, progressions of intensity occurred every five minutes with participants increasing workload by a Borg rating of 1 level until they started to experience an increase in symptoms or for a maximum of 30 minutes	-Patient-reported symptoms -Parent-reported perception of symptoms -Adherence to exercise program -Adverse events	-A greater rate of improvement in symptom scores was observed in the group that followed the aerobic exercise program -Adherence was lower in the aerobic training group -No intervention-specific adverse events	-The sample size was relatively small with a set of young participants with fairly high premorbid activity levels -No report of participants’ physiological responses to exertional test at the start or after the interventions --The exertion testing was an indirect focus of the study with the emphasis instead being on reporting on intervention results relative to symptoms at rest and adherence between the two groups
			Rationale: No specific rationale provided for mode or protocol selection
Leddy, 2010	Case series of exercise training with pre- and post- intervention exertional testing	13 participants (7M, 5F) 6 – 52 weeks post-injury, with age range of 16 – 53 years (mean = 27.9, SD 14.3 years); 6 of 12 participants were athletes	Mode and Type: Treadmill Walking: Incremental progressions in treadmill grade (modified Balke protocol/Buffalo Concussion Treadmill Test)	-Constant speed of 3.3 miles per hour, starting at 0% incline. After 1 minutes, fixed 2% grade increase; after 2 minutes, fixed 1% grade increase each minute until speed could not be maintained, post-mTBI symptoms returned, or max of 21 minute was reached	-Symptoms -Exertion duration -RPE -Physiologic measures	-No unexpected adverse events were reported, however 1 subject reported a mild, temporary increase in symptoms early in the treatment phase -After treatment, participants were able to exercise longer and able to achieve higher peak HR and blood pressure during exercises without symptom exacerbations	-Relatively small sample that were in a sub-acute recovery period -V02 was estimated but not directly measured
			Rationale: No specific rationale provided for mode or protocol selection
Leddy, 2011	Case series with participants who had a recent concussion to assess retest reliability on effort and physiologic measures and a set of actors without concussion to evaluate interrater reliability to determine symptom exacerbation	21 participants with concussion (11 M, 10 F), age range of 1554 (mean = 29.8, SD 14.8 years) who were an average of 33.2 weeks postinjury, 11 were athletes; 10 healthy, sedentary participants (4 M, 6 F) age range of 18 – 45 years (mean = 26.5, SD 8.2 years)	Mode and Type: Treadmill Walking: Incremental progressions in treadmill grade (modified Balke protocol/Buffalo Concussion Treadmill Test)	-Constant speed of 3.3 miles per hour, starting at 0% incline. After 1 minute, fixed 2% grade increase; after 2 minute, fixed 1% grade increase each minute until speed could not be maintained, post-mTBI symptoms returned, or max of 21 minute was reached	-Test-retest reliability of physiologic measures and RPE -Interrater reliability for identifying symptom exacerbation	-The protocol had good retest reliability for assessment of max HR in participants with a concussion and healthy controls (ICC of .79 and .64, respectively) -For max systolic blood pressure, the participants with concussion showed more variability (ICC of .37) compared to healthy controls (ICC of .90) -Max diastolic blood pressure reliability was low (ICC of .20) for participants with concussion compared to healthy controls (ICC of .50) -Reliability for RPE was relatively low (ICC of .42) compared to healthy controls (ICC of .80) -Raters achieved a sensitivity and specificity of 99% and 89%, respectively for ruling out concussion symptom exacerbation and agreed 304 of 320 observations an accuracy of 95%	-Relatively large age range with small sample, which makes it difficult to determine if age may affect the test retest reliability --Unclear if different subgroups (e.g., those with vestibular or oculomotor impairments) may respond differently since classifications were not a comparison parameter
			Rationale: No specific rationale provided for mode, but protocol choice was noted as selected based on prior studies
Manikas, 2016	Experimental study investigating the impact of exercise on symptom exacerbation and neurocognition at 2 time points (Days 2 and 10 post selfreport of symptom resolution	30 patients (25 M, 5 F) between the ages of 10 and 17 years of age; participants were tested two days and ten days after they reported resolution of symptoms; mean of 5.4 (range of 0–24) days until self-report of resolution of symptoms	Mode and Type: Cycle ergometer-modified version of the McMaster All-Out Progressive Continuous Cycling Test	-After a 2 minute warm-up, the resistance on the bike was increased by 25 or 50 Watts over 3 stages, based on participant height. Participants were instructed to keep the rotations on the bicycle constant for 6 minutes.	-Physiologic measures -RPE	-No report on HR outcomes in results -Maximum RPE was lower at Day 10 compared to Day 2 -Reduction in symptoms reported on Day 10 compared to Day 2	-The exertional testing was an indirect focus of the study as the emphasis was on how exertion affected neurocognitive functioning -Limited physiologic results were available
			Rationale “shown to be suitable for children”
Moore, 2016	Case series describing functional changes in adults with persistent post mTBI symptoms and disability after completing a supervised home exercise program with combination of vestibular and aerobic training	14 patients (6 M, 8 F) median age of 43 years (range 18–72) referred for vestibular rehabilitation; median time between injury and initial evaluation was 107 days (range 14–992)	Mode and Type: Cycle ergometer using a modified Balke protocol/Buffalo Concussion Test	-Incremental increases by a factor of two units every 2 minutes until participants reported exacerbation or until they reached 60–80% of their maximum heart rate or until they reported a 17 on RPE scale indicating the perception of “very hard” exertional level	-Symptoms -Physiologic measures -RPE -Return to Work/Study/Activity	-No report of BP, HR, oxygen saturation responses, or RPE to exertion, but these variables were used to guide home intervention program -Improvements were observed in symptom reports, function, and return to work and meaningful-activities	-No control group for comparison -Sample consisted of participants with identified vestibular impairments making it hard to know how this would generalize to patients without vestibular symptoms -Large range in age -Minimal reporting of specific exercise physiologic changes
			Rationale: A cycle ergometer was used instead of a treadmill due to the likelihood of head excursion that occurs while walking or running on a treadmill and to minimize conflicting sensory stimulation; no rationale for Balke protocol was specifically cited though prior mTBI studies were cited
Slobounov, 2011	Observational cohort comparison study of brain connectivity patterns at rest and in response to a physical exertion test	17 college athletes with a recent concussion and 17 college athletes with no history of concussion	Mode and Type: Cycle Ergometer: 4 stages of increasing resistance	Resistance determined by YMCA stress test, 4 stages of increasing resistance, 3 min per stage, progression to next stage was determined by heart rate	-Symptoms -Brain imaging before and after biking -Physiologic measures	-Imaging identified differences in connectivity patterns at rest and in response to exertion, although no differences in HR responses to exertion were identified between the cohorts	-The exertion testing was an indirect focus of the study, with the physiologic response results being of secondary interest -Limited physiologic results were available
			Rationale: No specific rationale provided for mode or protocol selection

^*M = male, F = female; HR = heart rate; RPE = Ratings of perceived exertion