Sweat after heavy exercise smells like ammonia

Some of you may have experienced a strange sensation after performing heavy exercise: your sweat smell like ammonia. If you're like some people, you may notice it when you take a shower and you may naturally assume that someone recently used some cleaning solution to wash the shower stall. Or, you may be wondering if you're experiencing olfactory hallucinations (or phantosmia). 

You're not having a temporal lobe seizure. The truth is that your sweat can smell like ammonia, especially after strenuous or extended cardiovascular exercise like running or cycling. Why?

The body produces ammonia as a byproduct when we burn amino acids and proteins as fuel. Normally, our bodies burn carbohydrates or fats as fuel when we exercise. All our major organ systems including our muscles and liver help to balance the right way that our body generates energy so that our muscles and brain are properly fueled with glucose when we exercise. Our muscles and liver convert glycogen to glucose. When our bodies switch to burning amino acids and proteins, our kidneys may be unable to excrete all the urea that is produced, so the excess nitrogen comes out of our bodies through sweat that smells like ammonia. Those who eat high protein diets or restrict carbohydrates prior to exercising strenuously may be especially prone to this issue. Remember learning about gluconeogenesis in medical school? How about glucose-6-phosphatase, fructose-1,6-bisphosphatase, PEP carboxykinase, acetyl CoA and citrate? Don't worry, I don't remember them either.  

Some athletes have even coined the term "ammonia sweat" because they experience this phenomenon on a regular basis. Those athletes may be the ones who are on carb-restricted diets (low carb, Atkins, Paleo, South Beach, etc.). In general, when these same people start increasing their carbohydrate intake, the problem with "ammonia sweat" tends to go away. 

Getting ready for some intense exercise? Fuel your body with carbohydrates before, during, and after you exercise so that your muscles have the energy they need.