After several years of training hard and working towards skiing fast, I am now in nurse practitioner school in – gulp – Connecticut. After reading Aubrey Smith’s interview with Holly Brooks – fantastic piece by the way, and good luck Holly!!! – I wanted to learn more about rhabdomyolysis and exertional rhabdomyolysis. I decided I might as well share it with FasterSkier readers in case others had a similar curiosity to my own.
What is Rhabdo?
Rhabdomyolysis is the breakdown of skeletal muscle tissue resulting in the release of myoglobin into the blood stream, and from there, into the urine. (Like hemoglobin, myoglobin carries oxygen, but only in the muscle tissue.) The kidneys are responsible for removing the myoglobin from the blood, but myoglobin is toxic to the lining of the kidneys. So we have a bit of a catch-22… pushing too much myoglobin through the kidneys can result in renal failure. Furthermore, because dehydration often exacerbates rhabdomyolysis, thick blood and low blood volume can result in less perfusion (blood flow) of the kidneys which by itself can result in kidney damage and kidney failure, less filtration by the kidneys, and therefore more time that myoglobin spends in contact with the kidney lining, harming it. Causes of rhabdomyolysis include crush injuries, trauma, surgery, overdose of certain drugs, various cellular and metabolic diseases, and overexertion.
The exertional type:
Exertional rhabdomyolysis is the same process of substantial muscle breakdown, but as a result of heavy exercise and dehydration. It often occurs in untrained individuals overexerting themselves, but in trained individuals the cause of rhabdomyolysis tends to be insufficient fuel delivery to the muscles (the glycogen depletion Holly mentioned).
Signs/Symptoms of Exertional Rhabdomyolysis
Severe muscle pain
Dark urine (can be “cola” colored) – as little as 200g of damaged muscle tissue can result in a visible change in urine color!
Potential Complications and Treatment
When the muscle cells lyse (split), other cellular components are released in addition to myoglobin, which include electrolytes. This can affect the electrolyte balance of the blood in dangerous ways. Here are several (of many) possible electrolyte imbalances, and here’s why we care:
- Hyperkalemia – too much potassium in the blood – potassium is released from lysing cells, resulting in hyperkalemia which can cause, among other things, cardiac dysrhythmias.
- Hypernatremia – too much salt in the blood – can cause cognitive changes, including seizures and coma, from brain cells shrinking up as salt in the blood pulls water out of the brain cells. (Other cells too, but we see the mental changes because of the shrinking brain cells.)
- Hyper/hypocalcemia – too much or too little calcium in the blood – can cause fatigue and muscle weakness, muscle spasms, nausea and vomiting, and cardiac problems. (I’ve smooshed the two together – they do present differently, but both are bad!)
In the acute phase, hydration is of primary concern in the treatment of rhabdomyolysis because it dilutes the blood and allows the myoglobin and its byproducts to pass more easily through the kidney. Diuretics are also used: they make you pee! Diuretics help the patient excrete the myoglobin and reestablish electrolyte balance. (When using diuretics, you are hydrating from the other end at the same time!) At the same time, it’s important to watch for things like cardiac arrhythmias, change in mental status, renal failure, high fevers, and acid-base imbalances, and treat them as they occur. After the acute phase has passed, it takes time for the body to heal. Range-of-motion of the affected muscles and joints returns slowly, as does strength – even weight-bearing can be difficult at first! Understandably, the amount of time required for recovery depends on the amount of damage done in the first place.
Head out of the textbook…
Anyone who’s experienced exertional rhabdo – Holly, Brent??? – please feel free to add to what I’ve written. What did it feel like? What treatment did you get? How long did the recovery take? When did you return to your normal functioning? How will you avoid it in the future, without cutting back on the racing you want to do?! This stuff comes from textbooks and articles for me, I have no personal experience with it.