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The Rise of Exertional Rhabdomyolysis in Crossfit, Running and Endurance Sports

Updated on August 25, 2016

Taking Your Workouts to the Extreme by Pushing Too Far

You might never have heard of acute exertional rhabdomyolysis. It's prevalent amongst our sporting society's need to go that extra mile, or push out those few extra repetitions of a CrossFit WOD when we know our body is screaming out for rest. Whether you're drawing near the end of your first Tough Mudder obstacle race event or hitting the run at the Ironman World Championships in Kona rhabdomyolysis could have an impact on your performance.

Rhabdomyolysis (often abreviated to rhabdo) is a relatively rare health condition that can be caused working out at very high intensity such as you might find during many CrossFit workouts and during ultra-endurance events such as Ironman triathlon's and Ultra-marathons (MacSearraigh et al 1979) as a result of an onset of skeletal muscle breakdown.

Acute exertional rhabdomyolysis is caused by injury to skeletal muscle. This subsequently leads to the release of myoglobin and other contents of our cells into the circulatory system. Whilst many say the condition is rare there are numerous reports of it's occurrence at extreme sports events and it's prominence is rising. An occurrence of low to moderate level acute exertional rhabdomyolysis can lead to a huge number of potentially serious conditions.

As our muscles breakdown myoglobin is released into the bloodsream. Myoglobin is a large protein molecule and it can subsequently have disastrous effects by crytalizing within or blocking the tubules of the kidneys subsequently leading to renal failure in severe cases.

One of the clear visual signs of rhabdomyolysis is extremely dark, brown coloured urine caused when these large myoglobin protein molecules clog the filtering system of the kidney as the body is trying to filter these substances into the urine.

Workouts that extensively stress us beyond normal level can cause exertional rhabdomyolysis
Workouts that extensively stress us beyond normal level can cause exertional rhabdomyolysis

How Do Doctors Diagnose Rhabdomyolysis?

The main medical test for rhabdomyolysis is related to our creatine phosphokinase (CPK) levels. Usually these will be expected to be at an upper limit of around 200 U/L however rhabdo will make our CPK levels rise over 10,000 U/L.

Creatine phosphokinase is an enzyme found within our muscle cells. When these are damaged CPK is subsequently released into our bloodstream. CPK itself is not particularly harmful to our body, it does however serve as a marker for the release of myoglobin into our bloodsream.

Medical Conditions and Effects Experienced as a Result of Acute Exertional Rhabdomyolysis

  • Hyperkalemia, An excessive level of potassium in the bloodstream. Extreme hyperkalemia is seen as a medical emergency due to it's capacity to cause potentially fatal abnormal heart rhythms.
  • Hypernatremia, Hypernatremia is defined as a serum sodium level greater than 145 mEq/L and has a high mortality rate amongst hospitalized patients.
  • Lactic acidosis results from problems with our ability to clear lactic acid from our bloodstream. Lactic acidosis will occur when our body's acid buffering systems are overloaded and tends to cause a pH in the blood of less than 7.25 with plasma lactate being greater than 5 mmol/L
  • Hyperphosphatemia. Hyperphosphatemia features abnorminally high serum phosphate levels.
  • Disseminated intravascular coagulation (DIC) leads to ineffective action of the body's coagulation mechanism. This may subsequently lead to thrombosis in the sub-acute or chronic form. It often leads to haemorrhage as clotting factors are exhausted. DIC can be assessed by subsequent evidence of both thrombin and plasmin activation as part of intravascular coagulation.
  • Renal failure refers to failure of the function of our kidneys to help filter waste products from our blood and causing a build-up of waste products in the body that may cause symptoms of shortness of breath, weakness, and confusion, as well as an Inability to remove potassium from the bloodstream in the form of Hyperkalemia which may lead to abnormal heart rhythm.

Line and Rust (1995)

What are the Symptoms of Rhabdomyolysis?

What symptoms should you be looking out for if you might be suffering from rhabdo?

  • Extreme muscle pain
  • Extreme swelling and soreness the day after a workout (Beyond usual DOMS levels)
  • Difficulty in moving and extreme weakness in the affected muscles
  • Extreme weakness in the affected muscles
  • Excessively dark brown urine as though severely dehydrated

Kettlebells are great for training, however..

Too many swings on a hot summers day could be contributory factors to rhabdomyolysis
Too many swings on a hot summers day could be contributory factors to rhabdomyolysis | Source

How to Tell the Difference Between DOMS and Rhabdomyolysis

You're feeling pretty tender after your last race or endurance training session, a little more than usual but is it DOMS or could it be more serious?

If you're hurting and it's beyond the discomfort you would normally experience it's recommended that you keep an eye on what's coming out the next time you need to pee. If your muscle soreness is severe, and, if your urine turns dark brown then you should seek medical attention immediately and consider taking on additional fluids in the form of water.

If you can't get in to see your local doctor quickly it's recommended that you report to your local Accident and Emergency department and their initial test should be of your creatine phosphokinase levels.

Causes of Exertional Rhabdomyolysis

As an athlete or coach it is always worthwhile to be aware of the potential causes of exertional rhabdomyolysis to ensure you're creating optimal conditions where possible for training and competition.

  • Poor hydration levels before during and after strenuous bouts of exercise have been known to lead to exertional rhabdomyolysis. Keep that drinks bottle handy in the car or when training and make sure you get plenty of fluids throughout the day.
  • Inadequate recovery from previous strenuous bouts of exercise can mean your muscle cells have not regenerated and are already damaged going into a bout of exercise.
  • Inadequate fitness levels before performing intense workouts. Build up training gradually before completing high intensity efforts.
  • Extremes of temperature and humidity- Heat and high humidity have been shown to be risk factors so consider where and when you do your workouts where possible and if competing in intense, hot and humid conditions have an adequate hydration and nutrition plan.

Rhabdomyolysis Has Been Seen in Marathon and Ultramarathon Runners

Marathons are a fantastic way to get fit but often put the body through extremes of endurance it is not accustomed to and can cause muscle breakdown
Marathons are a fantastic way to get fit but often put the body through extremes of endurance it is not accustomed to and can cause muscle breakdown

Individuals at Risk of Exertional Rhabdomyolysis and Subsequent Risk Factors

Assessing High Risk Individuals and Sports

Sadly the incidence of rhabdomyolysis is often difficult to determine and therefore likely to be severely underreported. At risk individuals are often those who are lacking condition such as returning with a vengeance from a long term injury, returning from an off-season break, or are participating in high intensity exercise in hot and humid climates (Rosenberg, 2008)

Sadly most reported cases of exertional rhabdomyolysis do not involve sportspeople and subsequently concern public service workers such as police and firemen as well as military personnel. (Sutton 2012).

Risk factors rise in situations of pre-season training such as in Soccer and American Football where athletes often start from a position of relatively low fitness after a break. Multiple daily practices in athletes such as triathletes are also an additional risk factor, especially where there is a risk of illness related to heat exposure.

In competition recent information has showcased a heightened incidence in ultra-marathon runners- even in some of the fittest. Our body is pushed to the limits by ultra running and endurance sports and the subsequent muscle damage over the course of events like ultras and Ironman triathlon's can have disastrous effects on our body.

Occurrence in Triathletes

As an extreme endurance sport, triathlon sees a relatively high occurrence of rhabdo. Thomas and Motley (1984) saw when analyzing triathletes compete in a long distance triathlon event involving 1.25 miles of swimming, 53.5 miles of bicycling, and a subsequent 13.5 miles of running,

Analysis showed that upon finishing the event that every athlete of the 24 tested showed a dramatic rise in their serum myoglobin levels and the fastest athletes showed the biggest levels of this. The authors found that

"Exercise-induced myoglobinemia appears to be dependent on intensity of athletic performance, measured as a function of time, distance, and activity performed"

If You Think You Have Exertional Rhabdomyolysis

Ensure you take on plenty of fluids and head to the Emergency department at your local hospital

How is Exertional Rhabdomyolysis Treated

Upon hospitalization the medical team will work to encourage aggressive fluid replacement and generate a high urine output in attempts to alkalinize a patient’s urine as well as the monitoring of renal function.

Owing to the inherent muscle damage the medical team will then look at rehabilitation of the affected muscle groups consisting a combination of active-assistance range of motion exercises within the patients pain threshold.

Physiotherapy will move from range of motion exercises to ergometers designed to provide a constant workload commencing at low levels for short periods of time and slowly building up timeframe to enhance muscular endurance.

Do Some Crossfit Workouts like Muph Have Potential to Cause Rhabdomyolysis?

The Rise of Rhabdomyolysis in Crossfit

For many doctors and medics the effects of CrossFit on the body is more than just the positives preached by the many practicers. Exertional rhabdomyolysis often occurs when exercisers over-exert themselves in the gym, often as a resuly of performing an extreme amount of repetitions at unaccustomed weight levels for extended periods of time which seems to follow many of the CrossFit WOD's published online and in Boxes across the globe. Therefore performing CrossFit workouts itself has become a risk factor for exertional rhabdomyolysis without intention.

Not all CrossFit workouts are done supervised at a local box and many websites where exercisers can pick up a 'Daily WOD' talk little about scaling of exercises for beginners beyond slight reductions in weights. Taking a workout to your local gym means you're not fully supervised and coached accordingly to get the best out of the workout in the safest possible scenario however there are reports in the CrossFit Journal warning exercisers of the dangers and effects of rhabdo (Glassman, 2006)

Whilst many CrossFit organisations state that Rhabdomyolysis is a rare condition experienced in CrossFit, online forums and surveys with CrossFitters highlight it's emergence, even within experienced participants who cite the internal culture as a key factor.

Unfortunately there are currently no scientific figures available on the prevalence of rhabdomyolysis in CrossFit to confirm or deny these claims. Only anecdotal details of it's sufferers which sadly does not confirm an increased incidence in the CrossFit population. As a result we would like you to fill in the survey question below to establish the occurrence within the community at a basic level. Your assistance is really appreciated.

Are You A CrossFitter?

Please help our survey. Do you know anyone or have you suffered Rhabdo as a result of CrossFit?

See results

Could A Low Level of Rhabdo be Good For Exercisers?

A low level of rhabdo can actually enhance muscle calcium levels for increased protein synthesis
A low level of rhabdo can actually enhance muscle calcium levels for increased protein synthesis

Could Rhabdomyolysis be a Good Thing for Athletes?

In it's worst case rhabdomyolysis often requires hospitalization but bizarrely a small level might be perceived to be of benefit to an athlete or gym goer. During rhabdo a rise in muscle cell protein levels can lead to enhanced protein synthesis and thus the subsequent enhancements and adaptations associated with training such as increases in cellular mitochondria and contractile protein.

It is very clear that mid to high levels of the condition are extremely bad for the athlete but at a low level it can provide some benefits which many a runner, triathlete or CrossFitter may have experienced.

Tough Mudder Midlands 2014 at Broughton House Northamptonshire
Tough Mudder Midlands 2014 at Broughton House Northamptonshire

Rhabdomyolysis and Obstacle Racing Events Like Tough Mudder

One of the biggest growing participation areas in sports and fitness is the sport of obstacle racing. With events like Tough Mudder, Spartan Race and the infamous Tough Guy pushing competitors to new levels that their body may be unaccustomed for.

Could the inherently intensive nature of obstacle racing as many competitors use their muscles in ways they might not have done so whilst training have potential to cause further increases in rhabdo cases? There has to be a possibility of this as subjecting a mildly trained individual to miles of running on a blisteringly hot summers day with some very intensive elements like rope climbs and lifts their body may not be accustomed to could certainly be a number of risk factors for rhabdomyolysis.

Tough Guy- The Ultimate Obstacle Course Race

Have You Ever Suffered?

We're always looking for reader feedback. Have you or someone you know experienced the effects of acute exertional rhabdomyolysis? What was it like, how did you do it and how long did your recover take?

Thanks for reading- Liam Hallam


Ellis C, Cuthill J, Hew-Butler T, George SM, Rosner MH. Case report: exercise-associated hyponatremia with rhabdomyolysis during endurance exercise. Phys Sportsmed. 2009 Apr;37(1):126-32.

Glassman., G., Crossfit Induced Rhabdo, CrossFit Journal, October 2005, 38

Line., R. L., Rust., G. S. Acute exertional rhabdomyolysis. American Family Physician. 1995. 52(2):502-6.

MacSearraigh ET, Kallmeyer JC, Schiff HB. Acute renal failure in marathon runners. Nephron. 1979;24(5):236– 240

Rosenberg J. Physician perspective. exertional rhabdomyolysis: Risk factors, presentation, and management. Athletic Therapy Today. 2008;13(3):11-12

Sutton, B. Exertional Rhabdomyolysis-Risk Factors and Preventative Measures October 19, 2012 by National Academy of Sports Medicine.

Thomas., B. D. Jnr, and Motley., C. P., Myoglobinaemia and Endurance Exercise: A Study of Twenty-Five Participants in a Triathlon Competition,' American Journal of Sports Medicine, vol. 12, pp. 113, 1984


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    • CyclingFitness profile imageAUTHOR

      Liam Hallam 

      6 years ago from Nottingham UK

      Thanks miked1919@ fitness society seems to now dictate a 'go hard or go home' attitude to training. Very little is talked of periodization and rest days yet we see constant motivational posters on pushing our limits

    • profile image


      6 years ago

      Good article. Fitness athletes have to know their limits. In my opinion, there is no benefit in pushing yourself beyond your resources. Competitive athletes do this in competition because peak performance is their objective, not maximum health and fitness gains.

      I was doing Crossfit workouts long before there was a Crossfit. It's great execise as well as all the other varieties are. I firmly believe in cycling your intensity instead of going balls to the wall every workout. Thank you for sharing important information.

    • AVailuu profile image

      Ashley Vailu'u 

      6 years ago from Central Texas

      Thank you for sharing!


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