Really, Amy? Are you asking me the color of my pee? I'm not suggesting you report the color to me. However, urine color can indicate a condition afflicts endurance athletes called acute exercise-induced rhabdomyolysis (AER). The media has once again brought this condition to the forefront with the recent hospitalization of several Oregon Ducks football team members.

What is AER?

AER is an acute, serious, and potentially life-threatening condition for which the hallmark symptom is cola-colored urine. AER occurs in the case of severe skeletal muscle damage sustained through injury or profound overexertion.

AER can cause damage to the kidneys, liver, and long-term nerve and muscle damage. The incidence of this condition in endurance athletes is still being determined [1].

Acute kidney failure may be less likely in AER than in other rhabdomyolysis causes [2]. Therefore, it is conceivable that some endurance athletes go undiagnosed and treated yet suffer from other long-term complications, such as damage to nerves and muscles.  

Signs and Symptoms

I listed the signs and symptoms of AER below [1], but not all athletes with AER exhibit these symptoms. Other conditions may cause these symptoms as well.

• Dark brown urine (cola colored) 

• Confusion 

• Vomiting 

• Muscle pain (not normal delayed onset muscle soreness) 

• Generalized weakness 

Causes of AER

As with many issues afflicting the endurance athlete, the cause of AER is a combination of "the 'perfect storm' where there are several [contributing] factors (heat stress, dehydration, [muscle exertion], non-steroidal anti-inflammatory [e.g., Alleve, Ibuprofen] or other drug/analgesic use, and viral/bacterial infection)." [3]

The most common cause of AER is "too much."

• Too much too soon (e.g., returning to sport or starting a new form of exercise without a gradual introduction).

• Too much eccentric contraction of the same muscle group (e.g., high reps of heavy-weight jump squats).

• Excessive heat (running long distances or racing in high temperatures without acclimatization).

Other significant contributors to AER include high exertion in concert with the following:

• Dehydration 

• Certain medications, namely statins and NSAIDs (Aleve, Ibuprofen)

• Hyponatremia (overhydration - too little sodium) 

When you look at the list of causes, it is sobering, right? How many triathlons and marathons have you raced under the "perfect storm" of extreme heat before being acclimated, dehydrated, taking painkillers (even though your coach told you not to), and coming off an injury or illness? 

One case study tested four ultra-distance runners (two different years) after they ran the 95-mile off-road West Highland Way Race [4]. All tested positive for severe cases of AER. Each raced in at least half of the "perfect storm" conditions. 

Takeaway

The takeaway from all this? Train smart with a solid training plan, do not take NSAIDs before or during a race, avoid racing when sick or after a recent illness, and acclimate to hot weather running or modify if you find yourself in those conditions unprepared.

As always, listen to your body. Be aware of contributors to AER and its symptoms. If you have cola-colored urine after extreme exertion and one more of the other signs, seek immediate medical attention; If treated early, we can reverse AER. When not appropriately treated, the long-term consequences could be severe; once an athlete has suffered from AER, they are more susceptible to recurrence.

Sources

[1] Brudvig T, Fitzgerald P. Identification of Signs and Symptoms of Acute Exertional Rhabdomyolysis in Athletes: A Guide for the Practitioner. Strength and Conditioning Journal. 2007 Feb;29 (1):10-14

[2] Sinert S, Kohl L, Rainone T, Scalea T. Exercise-Induced Rhabdomyolysis. Annals of Emergency Medicine. 1994 June;23(6):1301–1306.

[3] Clarkson P. Exertional Rhabdomyolysis and Acute Renal Failure in Marathon Runners. Sports Medicine. 2007 April;37(4):361-363.

[4] Ellis C, Cuthill J, Hew-Butler T, George S, Mitchell R. Exercise-Associated Hyponatremia with Rhabdomyolysis During Endurance Exercise. The Physician and Sportsmedicine Volume. 2009 April;7(1):126-131.