Reference: JAMA Pediatrics. 2019; 173(4):319–325
Concussion injuries have been highlighted to the American public through media and research. Increased awareness may partially explain the rise in the number of Americans diagnosed with concussions, most notably in adolescents. A 60 percent increase in diagnosed concussions occurred from 2007 to 2014 (3,529 to 8,217), with the largest growth in children and adolescents ages 10-18 (Orthop J Sports Med. 2016). Approximately 20%, of American adolescents have been diagnosed with a concussion (JAMA. 2017). While most clinicians and organizations agree that a 24-48 hour period of rest and limited physical activity immediately following a concussion is advisable (CDC. 2020 Apr), return-to-activity and return-to-play decisions are limited by a shortage of prospective data (American Family Physician. 2019 Apr 1). Previous guidelines advocated a continuation of the “rest-is-best” approach past the initial 48-hour period (Clin J Sport Med. 2013). However, this management continues to evolve. A new study suggests that participation in subthreshold aerobic exercise may speed the recovery period and is the subject of this review.
A prospective parallel-group randomized clinical trial was conducted with 113 adolescent athletes (aged 13-18 years) presenting within 10 days of a sports-related concussion (SRC). Athletes were randomized to subthreshold aerobic exercise which consisted of exercise on a stationary bike or treadmill for 20 minutes daily targeting 80% of the heart rate at which symptoms were exacerbated or to a placebo-like stretching regimen which consisted of gentle, whole-body, progressive stretching for 20 minutes daily without substantial increase in heart rate. Concussion was diagnosed based on International Concussion in Sport Group criteria. All patients had exercise tolerance assessed by the Buffalo Concussion Treadmill Test (BCTT) to determine the heart rate at which symptoms were exacerbated (Clinical Journal of Sport Medicine: March 2011). The subthreshold aerobic exercise and stretching interventions were initiated at a mean 4.9 days from injury. Recovery was defined as symptom resolution (score ≤ 7 points on the post-concussion symptom scale for ≥ 3 days) along with a normal neurologic exam and the ability to exercise to exhaustion without an exacerbation of symptoms on the BCTT. 103 athletes completed the study and were included in the analysis.
Athletes who participated in subthreshold aerobic exercise recovered in a median of 13 days (interquartile range [IQR], 10-18.5) compared to 17 days (IQR, 13-23 days) in athletes who participated in the stretching program (p=0.009). In addition, the aerobic exercise group demonstrated a trend toward a lower incidence of delayed recovery (>30 days) compared to the stretching group (4% vs 7%, p=0.08), though the number did not reach statistical significance. There were no significant differences between the groups in symptom reporting or reduction in total symptom scores.
This randomized clinical trial supports existing evidence for early initiation of subthreshold aerobic exercise for adolescents in the acute phase of sports concussion recovery. Further, this study supports that early active subthreshold aerobic exercise shortens an athlete’s recovery time.
The results of the study are limited by generalizability (younger children and adults were omitted) and the fact that participants were not blinded to treatment, so intervention bias is plausible but perhaps not probable since participants were uninformed as to which treatment would be better. Future studies may assess for expectation of benefit to mitigate bias. While nonsignificant in this study, the trends toward acceleration of total symptom score reduction and lower incidence of delayed recovery in the aerobic group, are interesting results that warrant further exploration. This study, however, is the first randomized clinical trial to demonstrate the benefit of individualized subthreshold aerobic exercise treatment prescribed to adolescents with concussion symptoms during the initial week after SRC and demonstrates that it hastens recovery and may contribute to reduced instances of delayed recovery. Larger prospective studies will be helpful in testing the conclusions of this study which will help inform future management of adolescent concussions in the acute phase of care.
For more information, see the topic Sports-related Concussion in DynaMed.
Kamal Mohiuddin is originally from southern California. He is currently finishing his PGY-1 year at the Memorial Health University Medical Center Family Medicine Residency program in Savannah, Georgia. Dr. Mohiuddin obtained his medical degree from American University of Integrative Sciences located in Cole Bay, Sint Maarten. His professional interests include full spectrum family medicine. With his free time he enjoys spending time at the local beach and partaking in the Savannah culinary scene.