What is Rhabdomyolysis, and Who is At Risk?

The medical condition known as rhabdomyolysis recently entered the national news when a number of college football players from the University of Iowa were hospitalized with symptoms that included dark urine (myoglobinuria) and impaired kidney function. University officials were quick to defend the strength and conditioning program which has played such a critical part in Iowa football’s success under head coach Kirk Ferentz.  Meanwhile, the local press scrambled to inform the public with medical information, with varying degrees of accuracy.

What Is Rhabdomyolysis?

In the simplest terms, rhabdomyolysis is damage to skeletal muscle tissue in which muscle fibers are ruptured and release their contents into the bloodstream.  Blood labs can quickly identify  elevated levels of muscle proteins in the blood, but the “smoking gun” before a stricken individual even goes to the hospital is urine tinted dark or even brown from iron-containing myoglobin.

Doctors first described this condition in the mid 20th century in association with crush injuries, such as sustained during falls or from automobile accidents.  The blood work associated with rhabdomyolysis shows the presence of muscle proteins.

In the case of the Hawkeye football players, it was learned that the hospitalized players had undertaken extreme workouts which included squats of 200+ pounds repeated for as many as one-hundred repetitions, within a 20-minute window.  While the average college athlete or former athlete may be no stranger to difficult workouts, that these football players wound up hospitalized should come as no surprise to people who have or are familiar with McArdle’s disease.

Muscles obtain massive amounts of energy on short notice by rapidly breaking down starch (called glycogen) into glucose molecules.  During strenuous physical activity such as  squats, the process of glycogen metabolism floods the working muscle cell with a surplus of ingredients for chemical energy, precisely at the time when it needs it most.

McArdle’s disease illustrates how critical this metabolic process is for meeting the demands of even brief anaerobic exercise.  Due to a missing or non-functioning enzyme, people with McArdle’s disease cannot metabolize muscle glycogen into glucose.  As a result, during strenuous activity they experience premature and dramatic fatigue and often may also experience painful muscle cramps and rhabdomyolysis.  It is very common for individuals with McArdle’s disease to be hospitalized following episodes of rhabdomyolysis, due to the complications such as a liver problems.

People with McArdle’s disease get injured during exercise because their muscles effectively run out of energy without warning.  Skeletal muscle requires energy both to contract and relax in sequence; when someone with McArdle’s disease gets out of a car and attempts to walk up three flights of stairs, they make demands of their legs which the muscle cells cannot reasonably meet. The quadriceps, the body’s largest muscle group, are abruptly robbed of even the energy necessary to bear the body’s weight against gravity.  The predictable result is failure, as the muscle stops responding altogether, and rhabdomyolysis, or often both.

In the case of the University of Iowa football program’s  incident, rhabdomyolysis occurred as the result of extraordinarily demanding workouts.  Too much weight, lifted too many times and in too short a time period, using the body’s largest muscle group (the quadriceps.)  Even for powerful college athletes, the body has limits which no amount of perseverance can safely overcome.

Who is At Risk for Rhabdomyolysis?

There are two primary groups of people at risk to experience rhabdomyolysis: athletes, and people with McArdle’s disease.  However, because people with McArdle’s often otherwise appear completely healthy, symptoms have historically been dismissed as laziness or poor physical conditioning.  Additionally, many people with the disease develop personal methods of coping specifically to avoid such traumatic episodes of muscle failure.

Athletes, ironically, are at perhaps greater risk due to the lack of general public knowledge about rhabdomyolysis and muscle injury, combined with stereotypical expectations for varsity athletes. Muscle failure, dark urine and days of soreness may simply be considered normal for extreme competitors, but the rhabdomyolysis-related hospitalization of more than a dozen college football players at the University of Iowa proves that the concept of simply “pushing through” fatigue is a myth, and a hazardous one.

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