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Exercise Induced Rhabdomyolysis: Physiologic vs. Pathologic Overload

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By Brian Wallace, Ph.D., FACSM, CSCS |

In sports and exercise, progressive overload is a key tenet of all training programs. Seems simple enough – you progressively overload a system over time and during recovery your physiology adapts and grows stronger – supercompensation.  However, getting it right can be a considerable challenge, i.e., pinpointing the optimal dose of a training challenge that elicits positive adaptations for a given individual but not so great as to provoke injury, overtraining and burn out.  This is especially a problem in a culture driven by the pervasive refrain: bigger, faster, stronger and, of course by extension, all the accolades that begets and motivates extreme efforts.

Exercise-induced rhabdomyolosis (often referred to as exertional rhabdo or ER) is one of the more serious examples of overload abuse and pathology. It is characterized by a breakdown in skeletal muscle cells due to extreme overexertion often exacerbated by exercising in high heat and humidity.  It typically occurs when the intensity and/or volume of exercise is increased too much and/or too rapidly thereby overpowering the body’s capacity for damage repair and supercompensation. It can occur after only one workout or too many high intensity workouts sequenced too closely together without sufficient recovery.  It is a potentially fatal medical disorder.

Early warning signs include muscle swelling, extreme muscle soreness/pain and the subsequent release of muscle enzymes and other biomarkers into the blood including:  creatine kinase (CPK), potassium, calcium and myoglobin.  The latter being an oxygen binding protein in muscle cells which, when leaked into the blood, causes the urine to take on a brownish color similar to Coca-Cola which could ultimately lead to renal failure if left untreated.  High levels of potassium in the blood can be dangerous because it can lead to cardiac arrhythmias, myocardial ischemia/infarction, and muscle weakness.  However, both potassium and CPK levels in the blood are known to increase after prolonged or intense exercise, often without any dangerous symptoms. Thus, medically significant ER is in fact best diagnosed when a combination of elevated CPK levels is coupled with the signs and symptoms of pathologic muscle damage – swelling, extreme soreness and dark brown urine.

Though significantly underreported, ER has become increasingly more prevalent in our athletic and exercise environments.  More recently, it has been reported in a wide variety of athletes including ultraendurance athletes, weightlifters (e.g., excessive volume of squats), athletes involved in explosive anaerobic exercise – high intensity interval training, spinning classes, Crossfit, Strongest Man competitions – all of which are great when managed properly; but they do often place a supramaximal stress on an individual’s physiology and at times take it to the breaking point for a susceptible individual… and we all do ultimately have a breaking point. Unfortunately, common sense does not always prevail.

Case in point: I worked with one of the premier strength coaches in the country a few years back who was training a variety of professional athletes. Unfortunately he trained everyone like they were a professional football player.  This was especially problematic when we got some professional golfers in the program – one in particular was at the top of the game.  Needless to say after one session he didn’t come back – couldn’t even hit balls for a week with many of the signs and symptoms of ER.  

It is imperative that all strength and conditioning coaches, athletes, personal trainers and exercise enthusiasts understand the symptoms and ramifications of this disorder and, most importantly, focus on following the precepts of gradual and progressive increases in overload/recovery within a well-designed periodization plan and modified as needed based on individual responses and lifestyle – the key to avoiding overuse injuries, overtraining syndrome and exertional rhabdomyolysis.

Dr. Brian Wallace is the chair of sports exercise science at the United States Sports Academy. 

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