BLOG: Monitored exercise is OK after concussion
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When sports organizations started recognizing the importance of concussion and creating protocols for return to play 20 years ago, it was widely believed that athletes should completely stop all physical activity until recovered.
The 2001 consensus guidelines for return to play after concussion (Kushner) made it very clear: No exertion until the athlete is asymptomatic. They also made it clear that return to play was based on the ability of the athlete to exercise to the level of their sport without symptom exacerbation. Deliberate or not, the return to play architects had identified exercise intolerance as a key feature of concussion.
My colleague, John Leddy, MD, and I thought we needed a systematic method of measuring exercise intolerance levels and its relationship to symptoms. We developed the Buffalo Concussion Treadmill Test based on cardiac stress tests.
We quickly realized that post-concussion, athletes who would normally have no trouble sustaining aerobic activity at a heart rate of 180 bpm and more would become symptomatic at much lower heart rate levels. Not only would they be breathing unusually hard at 120 bpm, for example, but they might experience headaches, dizziness, nausea or other symptoms. Our treadmill test was initially quite controversial because everyone thought exercise was dangerous post-concussion. What we have learned, through a series of very cautious research studies, is that exercise can actually speed recovery.
Space travel and ANS
You might be wondering why a head injury would affect heart function in the first place. The work of NASA scientists can help us understand the phenomenon. Space travel, it turns out, completely disrupts the autonomic nervous system (ANS). The ANS controls all sorts of vital functions we don’t normally need to think about, like breathing, heart rate and digestion. During strenuous exercise, the large muscles of the body need a lot more blood and oxygen, so the heart pumps faster to meet this demand. By contrast, the brain prefers a steady cerebral blood flow, regardless of exertion level.
The ANS works hard to keep the brain at this steady state during strenuous exercise. When the ANS is compromised – whether due to space travel or a concussion here on Earth – its regulation of blood flow falls apart, causing all sorts of symptoms. For this reason, astronauts must exercise 6+ hours per day while in space to avoid chronic ANS dysregulation when they return. Likewise, exercise can facilitate recovery from concussion.
Clinical trials
We have conducted two prospective, randomized clinical trials in adolescents (ages 13-18 years) with sports-related concussions. This age group seems to be more vulnerable than either children (<13 years) or young adults (>18 years) to experiencing delayed recovery from concussion.
In 2019, we showed that young athletes who began exercising within 10 days of a concussion at 80% to 90% of their symptom threshold (the heart rate that provoked concussion symptoms) for at least 20 minutes per day, 5 to 6 days per week, recovered 35% faster than those who only did nonaerobic daily stretching (Leddy et al. 2019).
We recently repeated the study, with a few modifications to address weaknesses in the earlier design. For example, instead of relying on patient reports of exercise, we monitored their exercise with heart rate monitors. In this study, the median time to recovery was 14 days in the exercise group vs. 20 days in the stretching-only group, about 45% faster, when you consider they typically come into the clinic around 6 days post injury. Perhaps even more importantly, a participant’s risk of persistent post-concussion symptoms (defined as 28 days, but in this age group often lasting for many months) decreased by 48% (Leddy et al. 2021).
Optometrists may be aware that oculomotor difficulties after concussion are extremely common – in part because oculomotor function is also dependent on the ANS. Using light exercise to speed recovery can also help to reduce or even resolve the oculomotor problems without further intervention. In our concussion care clinic, it is primarily those with delayed recovery and chronic ANS dysfunction who need oculomotor rehabilitation.
I’ll leave you with this advice to share with patients who have had a recent concussion:
- Don’t exercise if you aren’t feeling well.
- Use a heart rate monitor or wearable tracker to figure out the heart rate at which you become symptomatic; don’t exceed 90% of that heart rate.
- Do at least 20 minutes per day most days of any exercise you enjoy – walking, jogging, swimming, at this sub-threshold heart rate.
- Stop exercising if you begin feeling bad.
- After a week, check to see if you still experience symptoms at the same heart rate as before. Your threshold should increase each week.
References:
- Kushner DS. Am Fam Physician. 2001;64(6):1007-1015.
- Leddy JJ, et al. JAMA Pediatr. 2019;doi:10.1001/jamapediatrics.2018.4397.
- Leddy JJ, et al. Lancet Child Adolesc Health. 2021;doi:10.1016/S2352-4642(21)00267-4.
For more information:
Barry S. Willer, PhD, is a professor of psychiatry at the University of Buffalo (UB) Jacobs School of Medicine and Biomedical Sciences and research director at the UB Concussion Management Clinic at UBMD Orthopaedics and Sports Medicine in Buffalo, N.Y. His research interests include traumatic brain injury (TBI), including mild TBI or concussion; the impact of concussion on physiology; readiness to return to play; and emotional regulation post TBI.
Disclaimer: The views and opinions expressed in this blog are those of the authors and do not necessarily reflect the official policy or position of the Neuro-Optometric Rehabilitation Association unless otherwise noted. This blog is for informational purposes only and is not a substitute for the professional medical advice of a physician. NORA does not recommend or endorse any specific tests, physicians, products or procedures. For more on our website and online content, click here.
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