I think most of us are well-aware of the short-term impairments and long-term damage that result from concussions. However, science still has much to learn on this subject. In recent years we have seen the emergence of scales designed for grading the severity of concussions and to sometimes determine a timeline for a person’s return to normal activity. However, from one scale to another, evaluation criteria are quite disparate. Furthermore, there is no general agreement on how long after a concussion an athlete can safely return to the game.
Currently, science tends to focus on the neurological and cognitive consequences of a concussion. What should not be ignored, however, is the fact that when an athlete’s brain suffers damage, it loses its ability to send proper signals to the rest of the body. The only way to improve the fitness level of an athlete is through mechanical stimulation (i.e. training). If your brain cannot send the proper signals to your body, you cannot train and you lose fitness during the recovery process.
Some scientific evidence suggests the powerhouses of the brain cells (mitochondria) get disrupted following a concussion. The powerhouses of the brain cells are quite similar to those found in your muscles. The question is: if the powerhouses of your brain cells get disrupted and your brain loses its capacity to send information to your body, could the powerhouses of the muscles get disrupted as well? If so, not only will your fitness level decrease due to a lack of training, your fitness level will further deteriorate as a result of this muscle powerhouse disruption.
This aspect has not yet been scientifically validated, but I think it is a legitimate question. In my exercise physiology lab, I regularly test people affected by concussions and various other cognitive impairments. Although I have only made clinical observations so far, I have noted, in some cases, that the oxygen uptake kinetics (global aerobic and anaerobic reserves) of people affected by a concussion are even less efficient (anaerobic threshold and maximal aerobic capacity appearing much earlier) than those of normal sedentary people. When abnormal oxygen uptake kinetics are observed, constant fatigue and failure to recover can easily be explained and proper rehabilitation strategies can then be put forward. According to my observations, this type of problem may persist as long as two years after a person sustains a concussion.
This leads to another question. If we only concern ourselves with how the brain is recovering and forget the body is also affected, maybe even at the cellular level, should we consider bringing an athlete back to the game with an almost totally functional brain, but without a fully recovered body?
And lastly, if the body has not yet fully recovered and, as a result, has to spend more energy to reach pre-injury intensity levels, which increases fatigue, will the athlete be fit enough to sustain the next impact without any consequences?
So far, there are more questions than answers, but they must be asked if we want to provide athletes with the best and most efficient help.
Dr. Denis Boucher holds a Ph.D. degree in experimental medicine. He manages an exercise physiology laboratory in Quebec and a human performance consulting company in the United States. He has conducted the pre-season on-ice fitness evaluation program for the Philadelphia Flyers. His clinical expertise is in the fields of exercise physiology, nutrition and sport performance. He currently hosts and produces a weekly radio show on XM172 entitled ‘The Little Scientific World of Doc Boucher’ (in French). He will blog for THN.com throughout the season.