Prescribed Exercise for Managing Concussions — the CJSM Blog Journal Club

Our Editor-in-Chief Chris Hughes (R) and Jr. Assoc. Editor Jason Zaremski (L) taking a brief spell from their busy lives.

Our fifth edition of the year went live at the beginning of September, and it’s a special one:  we have devoted the entire issue to the theme of pediatric athletes.

Our guest editor Alison Brooks M.D., M.P.H. has assembled an impressive line up of authors, including John Leddy M.D. of SUNY Buffalo who is the lead on an interesting new study demonstrating the benefits of prescribed aerobic exercise in the recovery of adolescent males from sport-related concussion.

Our Jr. Assoc. Editor Jason Zaremski M.D. has submitted another insightful journal club piece looking at the details of Dr. Leddy’s study.

As fall approaches in the Northern Hemisphere, and spring in the Southern, sports-related concussions will continue to show up in a variety of sports our young athletes play.  This work from Dr. Leddy et al. (including both this new study and his CJSM 2018 study) will be transformative in the way we manage our athletes.

Enjoy the original research paper itself (here) and the journal club article (below).


Jason Zaremski M.D., Junior Associate Editor CJSM


Leddy JJ, et al. A Preliminary Study of the Effect of Early Aerobic Exercise Treatment for Sport-Related Concussion in Males. Clin J Sport Med 2019 29(5):353-360.


As the temperature begins to change and we enter the fall season, millions of student-athletes have returned to school and sport. With such large participation numbers in sport inevitably comes a rise in injury. One of these injuries is sports related concussions (SRC). In recent years, our overall knowledge of how to diagnose, manage, and treat SRC has improved thanks to the ever-growing research in this area. However, one aspect that is continuing to evolve is the timing and intensity of physical activity after sustaining a SRC. While rest (cognitive and physical) has been a mainstay of treatment in the past, there is a growing body of research that indicates physical activity may accelerate recovery versus physical rest only. Thus, it is our pleasure to provide this month’s CJSM Journal Club by reviewing Leddy and colleagues’ new work on the effects of early aerobic exercise as a potential treatment for SRC in adolescent males.


The primary purposes of this research is to compare early subthreshold aerobic exercise (STAE) versus prescribed rest and days to recovery from concussion for adolescent males. The authors hypothesized that STAE would reduce the days to recovery after treatment prescription.


After IRB approval and parental consent/minor assent were obtained, researchers compared 2 groups that were similar in age, sex, athletic background, and time since injury. Each group was provided with different recommendations after sustaining a SRC.

  • Group 1: (Rest Group-RG): A control group that was prescribed rest after sustaining a SRC. The rest group (RG) was comprised of individuals from a previously published study for which the study team had recruited participants (Leddy, et al CJSM 2018).
  • Group 2: (Exercise Group-EG) A group of male adolescents who sustained a SRC and were given an individualized STAE prescription after SRC.


Of the 67 participants consented for the study, 3 withdrew from the RG and 3 withdrew from EG. Additionally, 3 participants from RG and 2 from EG were removed because they failed to complete at least 75% of the daily symptom reports or missed 3 or more days in a row. 1 participant from RG and 2 from EG recovered in 2 days or less from the initial visit and were excluded. Thus, there were a total of 54 participants who sustained SRC within 1 to 9 days of clinic presentation (all males aged 13-18 years). 24 in the EG (15.13 ± 1.42 years, 0.71 ± 0.81 previous concussions) and 30 in the RG (15.33 ± 1.40 years, 0.33 ± 0.61 previous concussions).

Inclusion Criteria:

  • Males only between 13-18 years of age
  • Sustained a SRC <10 days prior to evaluation

Exclusion Criteria:

  • Evidence of focal neurological deficit
  • Inability to exercise because of orthopedic injury, cervical spine injury, diabetes, or known heart disease
  • Increased cardiac risk
  • Current diagnosis of attention deficit hyperactivity disorder (ADHD), learning disorder, depression, or anxiety
  • History of moderate or severe traumatic brain injury
  • Greater than 3 previous concussions
  • Inability to understand English
  • Recovery in 2 days or less from the initial visit
  • Sustaining another head injury before recovery
  • Having an initial post-concussive symptom score (PCSS) score of 5 or below
  • Not completing at least 75% of daily symptom reports or having missed 3 or more days of reporting symptoms in a row.

All participants in both groups were evaluated less than 10 days from injury and were diagnosed with a SRC by an experienced sports medicine clinician using standardized guidelines. Both groups followed up with the physician at 7 and 14 days after the initial visit.

All EG participants performed the Buffalo Concussion Treadmill Test (BCTT) at the first clinical visit to calculate the exercise prescription.  As the authors note, previous research has shown that performing the BCTT within 10 days of injury does not affect recovery and has no side effects. The EG was given an individualized STAE prescription based on their BCTT. Clinical recovery for the EG cohort, determined by physicians who were blinded to the treatment group, occurred when participants reported a baseline level of symptoms, had a normal physical examination, and could exercise without exacerbation of symptoms. RG participants were instructed to rest with no structured exercise.

Subthreshold Aerobic Exercise (STAE) Prescription and Monitoring

The EG prescription was based on 80% of the heart rate (HR) achieved at symptom exacerbation on the BCTT.  Before the test began, the participants rated their overall symptom state on a visual analogue scale (VAS, 0-10) They then walked on a level treadmill at 3.2 or 3.6 mph at 0° incline. The incline increased by 1° after each minute for the first 15minutes and then the speed by 0.4mph every minute thereafter.

The HR (monitored via a Polar HR monitor), symptom severity (VAS), and Borg Rating of Perceived Exertion (RPE) were recorded until symptom exacerbation or voluntary exhaustion (defined as 17 on the RPE scale per the authors), followed by a cool-down period to resting HR.  Symptom exacerbation was defined as an increase of 3 points or more from the pre-exercise VAS value.

EG participants were instructed to exercise at home or in a gym with supervision each day for 20 minutes on a treadmill or stationary bike at the prescribed HR with a 5-minute warmup and a 5-10 minute cool down. Exercise ceased if symptoms were exacerbated or at 20 minutes, whichever came first. Exercise that drastically increased HR was prohibited. Participants were provided a Polar HR monitor to measure their HR at home during exercise. They were told not to participate in any physical activity that could result in a head injury and were instructed to advance daily cognitive activities according to symptom tolerance. They completed a daily record of their symptoms (PCSS) and activity level online.

Relative Rest Prescription

The RG cohort were told not to participate in any sports, any other forms of exercise, or any physical activity that could result in a head injury, and they were excused from physical education class. They were instructed to advance daily cognitive activities according to symptom tolerance and provide a daily record of their symptoms and activity level similar to the EG. They reported their daily physical activity level through the same online form as the EG.

Data Acquisition:

All participants in both groups reported symptoms each day for 2 weeks. Participants begin reporting symptoms the day after the initial visit (day 1). Participants received daily email or text message reminders to access the online data form to record symptoms using the Sport Concussion Assessment Tool 3 (SCAT3) PCSS. Symptom recovery was defined as return to a baseline level of symptoms, which was defined as a symptom severity score of 7 or less for 3 consecutive days. For initial symptom scores between 5 and 7, the authors used the criterion of no symptoms to define recovery. The authors categorized PCSS symptoms into the following clusters: physical, cognitive, sleep, and affective.

It should be noted that none of the participants were kept out of school for more than 2 days and no participants were partaking in physical, vision, or vestibular therapy during the first 4 weeks of the study period.  Additionally, the physical examination was standardized among the study physicians through a 2-hour training session and included instruction on assessment of cervical, oculomotor, and vestibular function.

Statistical Measures/Analysis:  As the authors note from their manuscript: Statistical analysis was performed using Welch 2-sample t tests with unequal variances at level 0.05 to assess differences in age, previous concussions, days from injury to initial visit, and symptom scores at first visit between the EG and RG groups. The Fisher exact test (2-sided) at level 0.05 was used to assess group-wise differences in initial visit physical examination findings.  Welch 2-sample t tests with unequal variances at level 0.05 were used to assess differences in recovery time between groups and the Fisher exact test (2-sided) at level 0.05 was used to assess the rates of delayed recovery (>30 days). A P-value <0.05 was considered significant and because of the preliminary nature of these post hoc analyses.

T tests were conducted comparing day 1 to 14: total symptom score, physical symptom score, cognitive symptom score, sleep symptom score, and affective symptom score.  95% confidence intervals (CIs) based on a normality assumption for symptom scores were calculated for each day. Mean values and 95% CI were calculated for each group for each cluster on each day. Mixed-effects linear models were used to analyze the total symptom scores and the symptom cluster scores from day 1 to day 14. Fixed effects included group and time (days) with their interaction term in the model.

If there were missing values, then the average of the day before and the day after score was used. If scores for 2 consecutive days were missing, they were imputed using an average of the score on the latest day before and the score on the soonest day after. If there were any day 14 missing values, then subject’s score from day 13 was used.


The EG and RG were not statistically different in age, concussion history, time from injury to initial visit, day 1 symptom scores, or initial visit physical examination findings.

Recovery time from initial visit was significantly faster for EG than for the RG (8.29 ± 3.85 days vs 23.93±41.73 days, P=0.048).  Recovery time from initial injury was faster for EG than for the RG (13.04 ± 4.89 days versus 28.43 ± 41.78, P=0.052). As of day 14 the EG had significantly fewer participants who remained symptomatic in total (P=0.028), physical (P=0.028), cognitive (P=0.027), and sleep (P=0.011) clusters.  The EG had slightly more participants with affective symptoms on day 14 but it was not significant (P=0.816).  It is important to note that none of the 24 EG participants had delayed recovery, whereas 4 out of 30 RG participants (13%) had delayed recovery.  The average recovery time for the 4 RG participants with delayed recovery was 113.25±73.6 days.

The total, physical, cognitive, sleep, and affective clusters decreased significantly over time and were statistically significant. However, there was no significant difference in the rate of improvement of each cluster but none were statistically significant.  Total symptom score, physical symptom score, sleep symptom score all became significantly lower in EG compared with RG from day 4 onward. Affective symptoms were not significantly different between the 2 groups from day 1 to day 14.


This study by Leddy and colleagues adds to the SRC literature, particularly the immediate post treatment approach.  There were matched cohorts of a specific niche of participants, it was a focused study using validated measures, and has immediate implementable methods (exercise) to be used as a clinical tool that is safe and effective to expedite recovery after sustaining a SRC.


  • There were only male participants, but the authors note that this was done because it improved group matching, specifically in age, initial symptoms, and athletic ability.
  • Participants were not randomized to the respective treatments, though it would be not possible to blind someone to exercise versus rest. However, as the authors note, intervention bias is a possible confounder because the EG was given an active treatment and may have been more likely to report improvement versus the RG.
  • Physicians could not be blinded for the RG cohort because everyone in that study received the same treatment.
  • There was no specific tracking of the individuals who monitored the EG participants in their home exercise programs.
  • RG participants were not monitored for adherence to the recommended rest program.
  • As the authors noted, the subjects were recruited at 2 different times
  • Additionally, when reviewing the study used for the RG, a total of 37 males aged 14-19 in both cohorts were used in that study, whereas this study was 13-18 years old and 30 total so it would be helpful if that was explained in further detail.
  • Results of this study cannot be generalized to those that sustain a SRC other than Males 13-18 years of age with less than 2 prior concussions and those athletes without a history of ADHD, a learning disorder, psychological disorders, or a history of 3 or more concussions.


This study provides initial data for the efficacy of early active intervention via individualized STAE treatment during the first 9 days after SRC to expedite recovery in symptomatic male adolescents. Additionally, data from this study suggest that early exercise based treatment decreases the number of male adolescent athletes who experience prolonged recovery of greater than 30 days. When assessing symptom clusters, the majority of symptoms recover regardless of intervention or symptom category.

Clinical Relevance:

This study provides preliminary data for clinicians and sports medicine team members that indicate using STAE in male adolescent athletes with less than 2 prior concussions and no history of psychiatric disorders may safely expedite recovery from a SRC without risk of significant side effect.

About sportingjim
I work at Nationwide Children's Hospital in Columbus, Ohio USA, where I am a specialist in pediatric sports medicine. My academic appointment as an Associate Professor of Pediatrics is through Ohio State University. I am a public health advocate for kids' health and safety. I am also the Deputy Editor for the Clinical Journal of Sport Medicine.

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