Category Archives: Athletic Muscle Injury

DISCLAIMER:I cannot tout my approach to the management of this disease as safe or appropriate for others. Speaking only for myself, I know that exercise is the only effective way I can manage the symptoms of McArdle’s disease.  It really is up to you to be your own advocate and be as informed as you can. Ask questions. Learn about the human body. Take care of yours.

The symptoms of McArdle’s disease – exercise intolerance, muscle cramping and injury, weakness – often drive people with the condition away from an active lifestyle. It’s only natural to stop doing something that causes you pain.

The irony is that the more sedentary we are, the more potentially debilitating this disease.

The amazing machines in our muscles risk injury much sooner as we grow older, and our metabolism overall starts to slow, and our basic resting levels of energy start to fall off.

Our metabolism is a very efficient ballet of interdependent chemical reactions. Feedback from one activity is the cue that drives the rate of another. When energy demands on muscles are low, the body makes less energy available to them.

So how do you effectively manage the symptoms of a disease that makes exercise a dangerous endeavor? For me, the answer is by exercising.

More specifically – the kind of exercise that really sucks to undertake with McArdle’s disease:

  • Walking up inclines or stairs
  • Jogging for short spells, or sprinting for even shorter ones
  • Swimming
  • Lifting weights
  • Hitting a heavy bag
  • Planks

Any of these can result in some serious McArdle’s-related injuries and send you to the hospital. Most people with the disease wouldn’t dream of undertaking these or recommending them to anyone else (I certainly would not.)

And yet, my symptoms are most manageable only when I train my muscles to face such stimulus. I don’t want to go to the hospital, and that’s why I exercise every day. It works wonders for my ability to climb stairs, or walk through the mall with a friend without getting hypoglycemia. 

It doesn’t apply to everyone, we all have different problems coincident with this metabolic disease of ours. Some of us are in wheelchairs, some of us have diabetes. What the “training stimulus” looks like really has to be relative to your unique baseline.

But so too is physical fitness for “normal people.” They share the same amazing metabolic systems that up- and down-regulate in real time to conserve resources and operate as efficiently as possible. “Normal people,” too, get weak when they don’t train. “Normal people” get sick and hurt their muscles when they over-do it.

People with McArdle’s disease have to train and work hard to reach a capacity for exercise that most people take for granted. We may be reminded of this each time we do something as mundane as folding laundry, or tying our shoes, or putting air in our car’s tires.

For me, managing McArdle’s and avoiding injury exercise is by no means something I think I’ve figured out. It is a work in progress, and I am sure it always will be. (Again, something I think we McArdle-ers have in common with “normal people.”)


“How can anyone be so out of shape?” 

“Why don’t they  just try harder?” 

“Don’t they realize they’ll have to run more laps?”

Anyone who has ever ran laps in grade school gym class can probably recall stragglers.  Some were children with asthma or other health issues, but some consistently finished for no obvious reason.  For such children, it may very well have been the case that trying harder simply wasn’t an option.

When a child with no obvious physical infirmity is unable to meet basic physical fitness criteria, effort should be made to rule out McArdle’s disease, a rare and often undiagnosed muscle disorder marked by extreme exercise intolerance.

How McArdle’s Disease Makes it Difficult for Children to Run Laps

Also known as glycogen storage disease Type V or phosphorylase deficiency, McArdle’s disease is an inherited condition which impairs energy metabolism in skeletal muscle. During moderate to intense physical activity an enzyme called glycogen phosphorylase provides contracting muscles with the energy required to do work. In McArdle’s disease this enzyme either is either non-functioning or missing, and the result is premature exhaustion and failure which may be accompanied by cramp-like injuries to muscle tissue.

Screening Children for McArdle’s Disease: Simple Signs to Look For

Even with the wealth of information now available on the web, screening McArdle’s disease in children remains challenging. Undiagnosed individuals may have a healthy appearance and symptoms can easily be mistaken for laziness or behavioral problems.

For this reason, it is critical that the right people know exactly what to look for. Physical education instructors, teachers, school nurses and even other students can screen McArdle’s disease on the basis of one or more of the following criteria:

  • They seem abnormally out of shape despite a healthy appearance.  People with McArdle’s disease have trouble sustaining low- to moderate-impact activities such as climbing stairs or walking steep inclines, and consistently perform below average on standardized fitness evaluations.
  • They have trouble getting in shape.  Because their muscles do not metabolize energy normally people with McArdle’s fail to respond as expected to endurance exercise regimens.
  • They may experience cramping injuries accompanied by dark-colored urine.  As children reach adolescence, increased body weight, musculature and opportunity for competitive sports training may precipitate episodes of muscle failure and injury during activity. Telltale symptoms include painful cramp injuries called rhabdomyolysis, sometimes accompanied by myoglobinuria, a potentially life-threatening condition indicated by urine darkened by proteins entering the bloodstream from damaged muscle tissue.
  • They may avoid fitness evaluations or other physical activities. The conspicuous symptoms of McArdle’s disease can make children self-conscious and embarrassed, and the stigma of feeling different may lead them to avoid participating in physical activities altogether.


If you know of anyone who fits any of these criteria, please reach out to them and learn more about the challenges they face.  Children with undiagnosed McArdle’s disease may suffer from the perception that they are simply out of shape or lazy, so approach them with discretion but be patient and persist in asking the right questions.

Most importantly, always remember that diagnosis and treatment of McArdle’s disease should be left to qualified medical professionals.  Recent advances in medicine make conclusive diagnosis a matter of one or two clinic visits and a minor blood test.

Children and adolescents with McArdle’s disease can live active lives and be physically fit, provided challenges are undertaken safely and within the scope of the limitations of this disease.  Catching symptoms early gives children with this rare disease a better chance to feel normal.

For additional information about McArdle’s disease visit any of our homepage resources or the Muscular Dystrophy Assocation website.


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.