Recommendations that “rest is best” for concussions are based on animal research and consensus opinion. Recent evidence suggests that strict limitation of activity may not be beneficial. A small clinical trial (n=88) of pediatric patients with acute concussion randomized patients to “strict rest” for 5 days and “usual care” defined as 1-2 days of rest and then a gradual return to activities. (Thomas, Pediatrics 2015, PubMed ID: 25560444). The strict rest group reported more daily post-concussive symptoms and slower symptom resolution. There was no difference in neurocognitive or balance outcomes. In an observational cohort that included 2,413 pediatric patients, there was a statistically significant decrease in the proportion of patients with persistent post concussive symptoms in those who reported early physical activity. 24.6% of the patients with early physical activity and 43.5% of the patients with no early physical activity had persistent post concussive symptoms at 28 days (Risk Difference: 18.9%, 95% CI (14.7, 23.0%)). (Grool, JAMA 2016, PubMed ID: 27997652).

Aerobic exercise training has beneficial effects on autonomic nervous system, cerebral blood flow regulation, cardiovascular physiology, and brain neuroplasticity. Return of normal exercise tolerance is a primary determinant of physiologic readiness to return to a sport after a concussion.

Clinical Question

In adolescents presenting within 10 days of a sports related concussion, does a regimen of sub-symptom threshold aerobic activity when compared to a stretching program reduce time to recovery?



  • Male and Female adolescents (13-18 years)
  • Acute phase (within 10 days) of a sports related concussion (> 48 hours after injury)
  • Concussion defined by International Concussion in Sports Group criteria


  • Symptom severity score < 5 points on initial visit (Web Link: SCAT-3)
  • Ability to exercise to exhaustion without symptom exacerbation on first visit
  • Inability to exercise due to orthopedic or c-spine injury, diabetes or known heart disease
  • Diagnosis and treatment for ADHD, learning disorder, depression, anxiety
  • Increased cardiac risk (American College of Sports Medicine criteria)
  • Focal neurological deficit
  • History of moderate or severe TBI (GCS 12)
  • History of more than 3 prior concussions
  • A 2nd head injury during the study period
  • Limited English proficiency

Setting: 4 University-based outpatient concussion management clinics (Western New York State (3), Canada (1)), 9/2015-6/2018


Sub-symptom Threshold Aerobic Exercise:

  • Daily, supervised, stationary bike or treadmill at home or gym (walking/jogging if not available)
  • At a prescribed heart rate via a provided HR monitor
    • 80% of HR achieved at symptom exacerbation on the Buffalo Concussion Treadmill Test (BCTT) at 1st visit, adjusted each week
  • No stretching before or after exercise
  • Advised to stop if symptoms increased by 2 or more points from their preexisting level (on a 10-point visual analog scale) or at 20 minutes (which ever came first)
  • Advised to rest, including no gym class, aside from prescribed aerobic exercise and to limit activities that exacerbated symptoms (e.g. screen time)


  • Patients had access to usual care interventions such as advice for sleep hygiene, academic accommodations and judicious use of Acetaminophen and Ibuprofen for headache
  • Buffalo Concussion Treadmill Test was performed weekly at each clinic visit
  • Patient completed daily web-based log (received daily text reminders):
    • Post-concussion symptom scale completed until declared recovered by the study physician or 30 days (whichever came first)
    • Completion of the treatment intervention was recorded daily


Prescribed Stretching Program:

  • Instruction book describing a gentle, whole body, progressive stretching program with pictures and images that would not considerably elevate heart rate
  • Advised to stop if symptoms increased by 2 or more points from their preexisting level (on a 10-point visual analog scale) or at 20 minutes (which ever came first)
  • Advised to rest, including no gym class, aside from prescribed stretching and to limit activities the exacerbate symptoms (e.g. screen time)


Primary Outcome:

  1. Days to recovery since day of injury with recovery defined as:
  2. Symptom resolution: Symptom severity score 7 for 3 consecutive days
  3. Normal physical exam including neurologic, vestibular, oculomotor
  4. Ability to exercise to exhaustion without symptoms on the BCTT

Secondary Outcomes:

  1. Delayed recovery (symptom persistence > 30 days)
  2. Daily symptom scores


Interventional: Randomized Clinical Trial

Primary Results

Primary Outcome: Days to Recovery (From Date of Injury)

  • Aerobic Exercise: Median 13 days, IQR (10, 18.5 days)
  • Stretching: Median 17 days, IQR (13, 23 days)
  • Median Difference: 17 days – 13 days = 4 days (IQR not provided)
  • The authors considered a median difference of 3.7 days to be clinically significant in their sample size determination

Secondary Outcome: Delayed Recovery (> 30 Days)

  • Aerobic Exercise: 3.5% (2/57), median 50 days, IQR (46, 54 days)
  • Stretching: 13.7% (7/51), median 58 days, IQR (36, 62 days)
  • Risk Difference: 10.2%, (-0.7, 22.5%)

Secondary Outcome: Daily Symptom Reporting

  • Figure 3: Authors report a statistically significant difference with lower daily symptom severity scores over time in the aerobic exercise group


  • Rare, randomized trial in pediatric sports related concussion management
  • Concussion defined by International Concussion in Sports Group criteria
  • Participants completed 85% of daily symptom reporting and reported 89% completion of recommend exercises


  • Distribution of co-interventions not presented per study group in Table
  • Participants not blinded to treatment group
  • Symptom reporting and intervention compliance dependent on adolescent self-report
  • Per-protocol analysis only
  • Insufficient sample size for rare secondary outcome of delayed recovery (ARD=10.2%)

Author's Conclusions

“This study is, to our knowledge, the first to show that individualized sub-symptom threshold aerobic exercise treatment prescribed during the first week after sports related concussion safely speeds recovery in adolescents with concussion symptoms. This is not equivalent to a return to sport-specific play; rather, it is an early active intervention intended to improve recovery to the point where it is safe for the athlete to begin the graduated process of returning to his or her sport. The data provide preliminary evidence that a primary benefit of early subthreshold exercise treatment is a reduced incidence of delayed recovery (>30 days), which is potentially a very important result. Larger prospective studies should investigate mechanisms of action of aerobic exercise on the concussed brain and determine if prescribed early subthreshold exercise prevents some patients from having delayed recovery after concussion.”

Our Conclusions

The study’s results have the potential to change the discharge advice that we as providers give to our adolescent patients who are diagnosed with a sports-related concussion. Sub-symptom aerobic exercise starting 48 hours after injury might help patients recover faster. Faster recovery may lead to a lessened burden of social and academic problems. Athletes may be able to begin gradual return to play earlier.

Potential Impact To Current Practice

The study adds to the growing body of evidence in the pediatric population supporting early return to limited activity compared to strict rest.

The consensus statement on concussion in sport (October 2016), (Brit J Sports Med 2017, PubMed ID: 28446457) makes the following statement prior to the publication of the reviewed study:

“The basis for recommending physical and cognitive rest is that rest may ease discomfort during the acute recovery period by mitigating post-concussion symptoms and/or that rest may promote recovery by minimizing brain energy demands following concussion. There is currently insufficient evidence that prescribing complete rest achieves these objectives. After a brief period of rest during the acute phase (24-48 hours) after injury, patients can be encouraged to become gradually and progressively more active while staying below their cognitive and physical symptom-exacerbation thresholds (i.e., activity level should not bring on or worsen their symptoms). It is reasonable for athletes to avoid vigorous exertion while they are recovering. The exact amount and duration of rest is not yet well defined in the literature and requires further study.”

Read More

PEMCAR iBook (Apple version)


PEMCAR Critical Article Review (PDF)