Most people reading a blog post about returning to play after a concussion have likely heard of the term chronic traumatic encephalopathy (CTE). CTE is a neuro-degenerative condition that is caused by repeated head impacts. Researchers found that even sub-concussive blows (i.e., the hits that an offensive/defensive lineman would incur on every play) can cause CTE even though the impacts don’t meet the criteria of a diagnosable concussion.[1] For those who did sustain a concussion, it has been shown that sustaining a second concussion before fully healing from a prior concussion significantly increases the risk of a protracted recovery time and more severe cognitive, physical, and emotional symptoms. Additionally, even if you have fully healed from a concussion, you are still more susceptible to sustaining a subsequent concussion, indicating a lower force threshold necessary for injury.[2]
With this knowledge, protecting the brain should be paramount. The only way to prevent this degenerative process is to reduce the number of head impacts. Clearly, there is no way to prevent all head injuries, and head injuries frequently occur outside of sports. In this blog, head injuries in athletes are discussed as there is the most robust research in that population. In most contact sports, helmets are required to be worn. While helmets can prevent more severe injuries (e.g., a cracked skull), they can’t stop the brain from hitting the skull internally. Think about shaking a jar (skull) with a tomato (brain) inside. The jar does not have to make contact with anything for it to bruise the tomato. Given that an implantable helmet does not exist and that concussions will still occur in spite of preventative measures, how we treat athletes in the post-concussion period is extremely important.
Most organized sports follow a return to play (RTP)regimen. According to the Centers for Disease Control and Prevention (CDC), RTP steps are as follows:
Regular activities (e.g., school)
Light aerobic activities (5-10 minutes)
Moderate activities (e.g., jogging, brief running, less time/intensity for regular activities)
Heavy, non-contact activities (e.g., sprinting, weight lifting) in 3 planes of movements
Practice and full-contact (if appropriate for the sport)
Competition
The CDC specifies that each step must take a minimum of 24 hours, but more importantly, that athletes should not move on to the next step unless they are asymptomatic at the current step. Additionally, if they become symptomatic at any point during their RTP plan, the athlete should rest/recover as needed and then start again at the previous step. [3] If athletes follow these steps, they should not be at risk of returning to play before the concussion has healed.
However, there are significant limitations to this, most glaring that concussion symptoms are typically subjective (i.e., reported by the athlete), with limited ways to determine the presence of symptoms from an objective perspective (i.e., testing). Although it would be very difficult to prove this with research, athletes are likely not going to tell the whole truth and nothing but the truth if it would delay their return to play. (Call it personal prior experience, anecdotal evidence from treating concussions for the last 9 years, mom intuition…). For the sake of argument, let’s say that the athletes are truthful in their self-reported symptoms and follow the RTP steps diligently. They should be fully healed from their concussion and are cleared to return to play. But are they safe then?
A study by Lavoie et al.[4] researched dual tasking (i.e., completing a cognitive task at the same time as a physical task) as well as performance on the same dual task after exercise in post-concussion asymptomatic athletes (n=19) and a non-concussed control group of athletes (n=20). All athletes in the concussion group had sustained at least one medically diagnosed concussion, had completed a RTP protocol, were asymptomatic (self-report) at the time, were within 3-11 months post-concussion, and did not have any concomitant medical diagnoses. The athletes in the control group had never sustained a concussion. The study compared gait speed and scores on a dual tasking test (completing a complex cognitive exercise at the same time as walking on a self-propelled treadmill) in two situations, once without exercise and once after they completed physical exercise (20 mins on treadmill at 80-90% of their calculated maximum heart rate). Researchers found that ”engaging in a moderate bout of aerobic exercise enhances the cognitive performance of all athletes.” This is consistent with multiple previous studies. However, they found that the concussion group athletes “experienced a significant reduction in gait speed when completing the dual task after exercise, while no change was observed for the control group.” One hypothesis to explain these findings is that after moderate physical exercise, the concussed group had to slow their gait in order to complete the cognitive task accurately, while the control group did not.
In the guidelines set by the CDC, our current gold standard RTP test, neither incorporating cognitive abilities nor dual tasking are mentioned. Ideally, cognitive symptoms would be noticed during the first step, which would include returning to school/work, but there is no guarantee they would be connected to the concussion. The Lavoie et al. research showed that complex cognitive needs will require more energy for post-concussed asymptomatic athletes to the point of impacting their performance on a physical task. Some people might ask why that would matter if they’re playing a sport and not taking a history test. But sports are inherently very cognitively demanding. Take football for example. Yes, there is running and catching, but cognitive skills required to play football include reaction time, working memory, sustained attention, selective attention, processing speed, time management, decision making… (I could go on). The need to perform these cognitive skills may impact athletes’ ability to perform at their highest physical potential.
As discussed above, athletes’ ability to perform at the same level compared to their pre-concussion baseline is likely still impacted even when they are no longer symptomatic. But are there other potential consequences? A meta analysis completed by McPherson et al. [5] looked at eight studies that met their criteria for inclusion. They found that “athletes who had a concussion had 2 times greater odds of sustaining a [musculoskeletal] injury than athletes without a concussion.” Another study found that athletes during the 90-day period after returning to play post-concussion were 2.48 times more likely to sustain a lower extremity orthopedic injury compared to their non-concussed peers.[6] It is possible that the athletes became deconditioned during their concussion recovery, and therefore more susceptible to orthopedic injuries; however, the Lavoie et al. study noted that the researchers ruled out that the differences were due to deconditioning given that all athletes had completed the RTP protocol, and that they had no knowledge of other research that would support that hypothesis.
As a cognitive therapist, I have previously utilized dual tasking as a therapeutic goal. When I worked in neuro-rehabilitation hospitals, I would frequently see patients post stroke or severe traumatic brain injury who struggled to walk and talk at the time. A typical pattern would be that they would start walking, listen to a question, stop walking so they could process and respond, then start walking again. For these patients, I would set a goal for the patient to be able to continuously walk down the hallway while holding a conversation. While this may not sound difficult to most people, those patients have to expend significant cognitive resources just to walk correctly and talk correctly, so it can be extremely difficult to dual-task.
I have been in private practice now for close to a decade. My current patients are very high level, typically still working and managing their households while trying to recover from a concussion. It was recently brought to my attention that I rarely complete dual-tasking activities, incorporating both physical and cognitive tasks. Don’t get me wrong, I require my patients to do a lot of multitasking, but the activities are typically both cognitive. Some of this has to do with the location- I no longer have extensive hallways and multiple floors for walking, nor am I able to co-treat with the support of a physical or occupational therapist to help with the patient’s needs. While researching and writing this blog, I have determined that I need to return back to my dual-tasking activities. So if you are coming to see me in the future, don’t be surprised if I ask you to do jumping jacks while saying the months of the year backwards!
In summary, the current RTP protocols do not incorporate any cognitive and physical dual-tasking. Current research identifies that this is likely a mistake. Athletes are not able to perform at their maximum output level, and even asymptomatic post-concussion patients a more than twice as likely to sustain a musculoskeletal injury within a year of the concussion. The likely reasoning is that even subtle deficits in neurocognitive abilities can impair neuromuscular functioning, including speed, control, and coordination. Sending athletes back to play without dual-tasking assessments may be setting them up for orthopedic injuries that will lead to more extended time away from play, or could even be career ending. Testing and RTP protocols need to be adjusted to reflect the most up to date research in order to protect athletes from sustaining potentially preventable injuries.
https://www.bumc.bu.edu/camed/2018/01/18/study-hits-not-concussions-cause-cte/#:~:text=CTE%20causes%20brain%20cell%20death,both%20concussive%20and%20subconcussive%20episodes.l
https://www.cognitivefxusa.com/blog/multiple-concussions-effects-and-treatment#:~:text=It's%20worth%20noting%3A%20If%20you,lasting%20symptoms%20and%20brain%20damage.
https://www.cdc.gov/heads-up/guidelines/returning-to-sports.htm
Lavoie, G.; Bolduc, M.; Sicard, V.; Lepore, F.; Ellemberg, D. Maintaining Cognitive Performance at the Expense of Gait Speed for Asymptomatic Concussed Athletes: A Novel Dual-Task and Post-Exercise Assessment. Brain Sci. 2024, 14, 715. https://doi.org/10.3390/brainsci14070715
McPherson, A.L.; Nagai, T.; Webster, K.E.; Hewett, T.E. Musculoskeletal injury risk after sport-related concussion: A systematic review and meta-analysis. Am. J. Sports Med. 2019, 47, 1754–1762.
Brooks MA, Peterson K, Biese K, Sanfilippo J, Heiderscheit BC, Bell DR. Concussion Increases Odds of Sustaining a Lower Extremity Musculoskeletal Injury After Return to Play Among Collegiate Athletes. Am J Sports Med. 2016 Mar;44(3):742-7. doi: 10.1177/0363546515622387. Epub 2016 Jan 19. PMID: 26786903.