Concussion and mild traumatic brain injury in sport has been gaining significant attention in the literature. With the incidence of concussion being estimated at 1.6 to 3.8 million cases per year in the United States during sports and recreational activities (7,23), the topic is now at the forefront of sports medicine professionals and the national media. Concussion management guidelines have been adopted and widely disseminated by international experts (29). These guidelines propose an interdisciplinary and multifaceted approach to concussion assessment and management.
Included in concussion management is a graduated “return-to-play” protocol. Because of the close relationship of strength and conditional professionals with sports medicine professionals, it is likely that strength and conditioning professionals will be directly working with athletes recovering from a concussion. This is likely to occur during the prescribed return-to-play protocol, or after the athlete has been discharged to return to full athletic participation. Conversely, many recreational athletes may go undiagnosed and unmanaged. In either case, it is important that strength and conditioning professionals working with any athlete, either competitive or recreational, have a strong grasp of the incidence and etiology, pathophysiology, and signs and symptoms of sport concussion, as well as the recommended concussion management guidelines. This article aims to educate strength and conditioning professionals on the current concepts of sport concussion and discuss implications for training athletes recovering from or with a history of concussion.
In response to the growing need for a unified approach to the treatment of athletes with sports-related concussion, the Concussion in Sport Group (CISG), an international task force of experts, has met in 2001, 2004, 2008, and most recently in 2012 to produce a consensus statement on concussion in sport. The CISG defined concussion as follows (29):
“Concussion is a brain injury and is defined as a complex physiological process affecting the brain, induced by traumatic biomechanical forces.”
In addition, they indicated that there are a number of common features incorporated in defining the nature of concussive head injury. These common features, as outlined in the CISG, are summarized in the following (29):
- Caused by a blow to the head, neck, face, or somewhere else on the body.
- Results in rapid onset of short-lived neurological impairment that resolves spontaneously.
- May result in neuropathological changes but the acute clinical symptoms largely reflect functional disturbances rather than structural injury.
- Results in a graded set of symptoms that may or may not include the loss of consciousness.
- Resolution of clinical and cognitive symptoms generally follows a sequential course.
- Postconcussive symptoms may be prolonged in a small percentage of people.
- No abnormality is seen on standard structural neuroimaging.
INCIDENCE AND ETIOLOGY
Estimating the number of individuals affected by concussion each year is a difficult task. Before 2006, many publications quoted the rate of 300,000 sports-related concussions per year in the United States. This number was originally extrapolated from the data collected in a 1991 National Health Interview Survey. At that time, a concussion was defined as a mild head injury that caused a loss of consciousness but did not cause death or long-term institutionalization (39). However, more recent investigations have concluded that an athlete does not need to lose consciousness to experience a concussion. In fact, loss of consciousness only occurs in 8–19% of the cases (19). By applying this new definition to the original survey data above, Langlois et al. (23) adjusted the estimated rate of sports concussions up to 1.6–2.8 million individuals per year.
Concussions have been found to occur in athletes of various levels of competition and sport. Epidemiological studies have been conducted to examine the prevalence based on sports in both high school and collegiate athletes. A study by Meehan et al. (31) examined 544 concussions through the High School Reporting Information Online injury surveillance system and found a distribution among various sports, with football being most prevalent followed by girls’ soccer. Further data for the involvement in other high school sports is presented in Table 1. An additional epidemiological study examining the prevalence based on sport participation in the collegiate population resulted in similar findings (16). The injury rates per athletic exposure based on sport are outlined in Table 2.
Many athletes who experience sports-related concussions do not go to the emergency room or visit their physician for care (11,27,40). In fact, these athletes often never report their injuries. McCrea et al. (27) found that only 47.3% of high school football athletes will report their injuries. Another study following Minnesota High School football players found that only 22% of players who experienced concussions were examined by medical personnel, and 29% received no examination (11).
It should be noted that these injuries seem to be more common in the younger population (3,22). This is likely the result of the fact that concussions occur more frequently in collision sports (12,21,40), which are most often played by younger individuals. Strength and conditioning professionals are often exposed to young athletes throughout the year because they participate in organized school and club sports or during their training for these sports. An understanding of the signs and symptoms associated with concussion is important because strength and conditioning professionals may likely have the opportunity to identify symptoms in their athletes because of the time of exposure and interaction with them.
As indicated by the CISG, a concussion does not produce positive findings in typical neuroimaging series. Therefore, interaction with these individuals usually demonstrates no overt signs of injury that would be seen with typical musculoskeletal injury. This can lead to uncertainty for athletes, coaches, and other individuals dealing with a concussion event. Having a basic understanding of the underlying pathophysiology that occurs immediately and in the subacute phases of a concussive injury can help bring some clarity as to what might be going on inside the athlete’s brain and underscore the importance of an appropriate response.
Given the definition of concussion above, one can envision that a sudden blow to the head or body may transfer forces through the skull, creating acceleration, deceleration, and/or torsional forces through the brain tissue. These forces cause a degree of tissue deformation or stretching that, at a high enough threshold, results in axonal and cell membrane disturbances and abnormal ionic flux.
As a result, excitatory neurotransmitters may be indiscriminately released. These transmitters cause further depolarization of the neurons, and there is a cellular release of potassium with an influx of calcium (18,20,38). Sensing this imbalance, the sodium/potassium pumps in the cell membrane go into overdrive trying to restore balance to the system. Unfortunately, these pumps are powered by adenosine triphosphate. Because they are working at full speed, the induced hypermetabolism creates an energy crisis of sorts (2,26,34). Efforts to catch up with oxidative metabolism are theoretically thwarted by intracellular congestion of calcium, which may impede the function of the mitochondria and its ability to produce adenosine triphosphate (17). The elevated calcium level in the cell can also lead to signaling for programmed cell death and is thought to be connected to a period of postconcussive vulnerability because the system may be less likely to respond to another acute event, heightening the dangers of second impact syndrome (13).
After the initial period of accelerated glucose utilization, the concussed brain goes into a period of depressed metabolism. This depressed metabolism and chemically imbalanced state may be responsible for positive findings that we see in symptom checklists, cognitive assessment, and balance testing. This is a simplified description of the process and is based on the experimental models of more serious traumatic brain injury. It is difficult at best to predict the exact physiological status of the brain because it deals with an injury, but this model is designed to help form a more palpable framework upon which to understand recovery.
SIGNS AND SYMPTOMS
When an athlete sustains a concussion, he or she can present with numerous signs and symptoms across a broad spectrum. The Centers for Disease Control and Prevention breaks down the signs and symptoms of concussion into 4 categories: cognitive, physical, emotional, and sleep (4). A listing of typical signs and symptoms is included in Table 3. In addition the CISG created the Concussion Recognition Tool at the 2012 International Conference for Concussion in Sport to assist the public in the identification of signs and symptoms of concussion (29). As the athlete recovers from concussion, the brain attempts to restore a normal physiological state and return to a premorbid state of homeostasis. At this point, activities that are stressful to the system can exacerbate symptoms and interfere with recovery.
Any athletic organization, competitive or recreational, should have a concussion management plan in place for its health care providers. In April 2010, the National Collegiate Athletic Association (NCAA) Executive Committee adopted a policy outlining the need for a formal concussion management plan (32). This policy is stated in Figure 1. Furthermore, the NCAA formally created concussion management plan legislation for all of its member institutions in all divisions, outlining the components of the concussion management plan (32). This legislation is provided in Figure 2.
Furthermore, best practice recommendations by the NCAA include the establishment of clear communication of roles among health care providers involved with the athletic team. Although the sports medicine physician generally will make the ultimate decisions on care, recognition of each provider’s scope of legal and professional practice to make decisions is necessary. Furthermore, care should be based on a baseline symptom checklists, cognitive and balance assessments, and neuropsychological testing (32).
CONCUSSION MANAGEMENT: ASSESSMENT
A concussion evaluation consists of the evaluation of somatic, cognitive, and emotional symptoms, physical signs, behavior changes, cognitive impairment, and sleep disturbances (29). The foundation of concussion management is a symptom assessment. Symptoms are assessed immediately after a concussion is suspected and then routinely reassessed throughout the recovery and return-to-play process (15).
The most commonly used instrument for identifying and tracking the presence and severity of symptoms is a graded symptom checklist, similar to that proposed by the National Athletic Training Association’s position statement on concussion in sport (15). In like fashion, a symptom evaluation is included in a component of the Sport Concussion Assessment Tool 2 (SCAT2). The SCAT2 was developed in 2008 by the International Conference of Concussion in Sport and openly disseminated for public use (30). It was revised in the 2012 International Conference of Concussion in Sport in 2012 to the SCAT3 (29). This tool incorporates both the symptom evaluation and the cognitive and physical evaluation (see Supplemental Digital Content 1, https://links.lww.com/SCJ/A117).
The number and type of symptoms that initially occur have been found to impact one’s recovery. A study by Makdissi et al. (25) found that delayed return to sport correlated with the presence of 4 or more symptoms and reports of fatigue and fogginess. In addition, the authors found that those athletes who had complaints of headache lasting for more than 60 hours to be delayed in their ability to return to sport, and conversely, those who had complaints of headache less than 24 hours returned to sport sooner.
The motor domain of neurological function is assessed through postural stability (balance) assessments. It has been shown that balance deficits typically last up to 72 hours after a concussion episode (14). Assessment of postural stability can be performed through either sophisticated balance systems or a reliable clinical test, such as the balance error scoring system test (10).
In addition to symptom assessment and physical (balance) assessments, additional cognitive function assessment through neuropsychological testing has become commonplace in assessment and management. Neuropsychological testing is now recommended by many professional sports organizations, the National Athletic Training Association (15), and specifically identified by the CISG as contributing to the comprehensive evaluation of concussion (29). It has been shown that recovery of full cognitive function through neuropsychological testing often follows symptom resolution (1,25). Thus, in the absence of neuropsychological testing, return-to-play decisions should be more conservative. Standardized neuropsychological tools are available and becoming widely used, such as the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) and CogState. These tests have been validated, shown good reliability (35,36), and have added significant value to concussion assessment. In a study by Van Kampen et al. (41) researchers found an increase in the sensitivity of concussion detection from 64% to 83% with the addition of ImPACT to the assessment process compared with the diagnosis on the use of symptoms alone. In a study by Makdissi et al. (25), researchers found that 35% of their athletes measured as having “impaired” cognitive status based on computerized testing 2–3 days after full symptom resolution. These studies further support a conservative approach to management.
Through reviewing these categorical assessments, it can be discerned how concussion assessment is multifaceted, involving trained professionals with differing backgrounds, such as athletic training, sports medicine, and neuropsychology. The management of athletes recovering from a sports concussion and return-to-play process is equally interdisciplinary. The comprehensive assessment and management plan should take special consideration in the analysis of the aforementioned tests in relation to baseline assessments. All athletes, whether elite or nonelite, are recommended to have baseline assessments, and this information should guide return to activity (29).
MANAGEMENT: RETURN TO PLAY
The cornerstone of concussion management is physical and cognitive rest (29). Physical rest is achieved through removal from all physical activity, not only competition but also all forms of exercise. Cognitive rest involves both academic and nonacademic behaviors. Athletes should refrain from schoolwork, leisure reading, and other activities that require concentration and attention such as video games (24). These periods of rest should last until symptom resolution (15,29,32). It is important that practitioners should ensure an athlete to be asymptomatic before engaging in any exercise program.
Once an athlete is asymptomatic, the sports medicine team should initiate a graduated return-to-play program. This program consists of 6 stages with the recommendation that athletes have a period of 24 hours between each stage. Thus, according to these recommendations by the third International Conference on Concussion in Sport (29), an athlete should not return to play until at least 1 week after symptoms have resolved. During each phase, the athlete is monitored for signs and symptoms of postconcussion, such as headache, fatigue, fogginess, and the like. After participation in each phase, a symptom checklist should be completed. If symptoms are present, the athlete rests for 24 hours and then reverts back 1 phase. The recommended graduated return-to-play program by the CISG is presented in Table 4.
It is the recommendation of the authors of this article that dosing of exercise during the return-to-play program is fully discussed with the managing physician and/or sports medicine team because there may be confounding factors to be considered such as history of repeat concussions, severity of the recent concussive episode, or previous symptoms during recovery. If an athlete is progressed too rapidly through the return-to-play program or returns to full competition prematurely, there may be significant consequences. Athletes recovering from concussion who are progressing too rapidly may develop prolonged symptoms and mental health issues such as depression. Even more significantly, athletes who return quickly may be at risk of developing second impact syndrome or eventually chronic traumatic encephalopathy (28). It should be noted that in the 2012 International Conference on Concussion in Sport, the CISG unanimously agreed that no return to play on the same day of a concussive injury should occur (29).
Per the return-to-play protocol, athletes should initiate exercise only when asymptomatic. Exercise begins in a light aerobic fashion, with the intensity below 70% of the maximum predicted heart rate. No specific duration is provided by the recommendations (29), nor is it provided in many university athletics protocols or by the NCAA (32). In addition to previously discussed factors, it is reasonable to believe that dosing may include some specificity related to sport-specific factors. It is also very important in this stage that heavy resistance training is avoided because of the potential for increased intracranial pressure (8). It seems the primary mechanism causing increased intracranial pressure during resistance training is performance of the Valsava maneuver (33). The tendency to perform a Valsava maneuver for many individuals is common during their heaviest lifts. Therefore, using lighter weight will decrease the likelihood of an athlete performing the maneuver and avoid the negative consequences of increasing intracranial pressure in this population.
The next stage of the return-to-play protocol is the sport-specific phase. This phase focuses on adding functional movements, which may include activities such as gentle cutting and/or agility tasks to aerobic activities from the previous day. There will also be a low level of cognitive interaction during these functional, sport-specific drills. However it should be noted that heavy resistance training and excessive anaerobic stresses are still avoided at this point.
Progression of the athlete to the next phase should include noncontact training drills with aims to add greater cognitive stress and coordination to the exercise prescription. In addition, this phase allows for heavier resistance training, which can increase intracranial pressure. As intensity of these drills increase, anaerobic stresses can be added to the drills or through normal exercise prescription.
Full-contact practice is the final step to returning to competition. This is a vital phase because it allows normal contact drills, which will likely include activities that caused the concussion. This phase is only entered with medical clearance, and only the sports medicine physician, in consultation with the sports medicine and strength and conditioning teams, should clear the athlete for full return to play.
Return to play should be a decision that is multifaceted and not reliant on any one variable. Consistent with the return-to-play recommendations by the CISG (29), additional factors have been proposed to guide an athlete’s return to play, which include the following (24):
- Athlete must be asymptomatic at rest
- Athlete must be asymptomatic during and after full cognitive and physical exertion
- Balance/postural stability must return to baseline
- Neuropsychological/cognitive testing must return to baseline.
ADDITIONAL CONSIDERATIONS FOR THE STRENGTH AND CONDITIONING PROFESSIONAL
As strength and conditioning professionals interact with athletes after concussion, it is imperative that open communication is standard practice. All members of the sports medicine and strength training teams must be aware of the recovery process of each individual athlete. In addition, it is essential that there is open communication of any additional confounding factors. Athletes with repeat concussion history may be placed at risk for prolonged recovery. In addition, it has been shown that females have an increased duration of recovery and severity of symptoms (5,6). Thus, they are more likely to become symptomatic during physical exertion during the return-to-play protocol. In a similar manner, younger athletes are slower to recover cognitively compared with college and professional athletes (6,9,37).
In addition to these factors, all members of the sports medicine and strength and conditioning teams must be cognizant of modifiers to the graduated return-to-play protocol. These modifiers were presented by the third International Conference on Concussion in Sport and are included in Table 5 (29).
Strength and conditioning professionals are very likely to encounter athletes who have had a recent concussion and are likely to interact with athletes shortly after a concussion incident. Because strength and conditioning professionals are also typically involved in preseason assessments, they may be involved with some of the baseline data collection procedures as well. As a result of their close interactions with athletes throughout season and offseason training, the strength and conditioning professional must understand when an athlete is presenting with postconcussive symptoms and should be evaluated by a member of the medical team. Not only are strength and conditioning professionals in positions to witness events that could cause concussive episodes, but also they have routine interaction with athletes and thus are in position to recognize abnormal behaviors or signs and symptoms consistent with concussion. Common occurrences that may lead to cause for referral to an appropriate medical provider are as follows:
- Witnessing a significant impact and reaction in the athlete that could lead to suspicion of a concussion (loss of consciousness, unsteadiness, etc).
- Communications with athletes during conditioning time may suggest that they have an altered cognitive status or balance.
- Communication with other teammates may give insight that another athlete received a particularly hard blow or is showing symptoms, which are not consistent with their normal behavior.
- Observation of athletes during a conditioning program, which promotes suspicion, including forgetfulness, difficulty with visual focus, or difficulty following directions.
Should the strength and conditioning professional note any of these considerations a referral is necessary. Findings should be communicated to the medical team, which often includes the athletic trainer and sports medicine physician. Specific signs and symptoms should be noted and the circumstances surrounding the occurrences of the symptoms should be communicated (time, location, activity). It is imperative that these findings be communicated as soon as possible. Practice and training activities can be hectic times, and a lack of communication could subject the athlete to further trauma.
Concussion assessment and comprehensive management including return to play requires active participation and monitoring of an interdisciplinary team. Athletic trainers, physicians, other sports medicine providers, and strength and conditioning providers will interact with athletes as they recover from concussive events. In addition, with the levels of underreporting or diminished monitoring in less organized sports and recreational activities, it is possible that strength and conditioning professionals will be the first to encounter individuals with concussive symptoms. A working knowledge of the etiology of concussion, awareness of signs and symptoms, and understanding of best practices for the management of sports concussion is necessary, so proper referrals and interactions with sports medicine providers can lead to the best care of their clients.
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