6 Causes of Muscle Cramps

Q: Hi Gale, I've been meaning to ask your opinion on something. Why do you suppose all three of us knuckleheads from Colorado cramped up at IM Wisconsin? Is that usually sodium deficiency?

The bike went well. I felt great on the run until I couldn't run anymore after 4 miles. Everything below my knees wanted to cramp. I walked the rest of the race with Nick. I tried to run one more time at about mile 9 and both hamstrings seized up. It was not a pretty sight.

I followed my fuel plan. I took lots of Enduralytes and consumed about 300 calories per hour of total fuel. I'm just curious what caused my cramping, and I thought I'd ask your opinion.

Thanks in advance,


A: Hey Dan, great question about what causes cramps.

First, there is no central agreement among experts on the exact cause of cramps. I'll list some of the issues thought to contribute to cramps, but remember that what may be an issue for one person is not an issue for the next.

From the items below, I suspect some do not apply to you and your buddies. Take a look see if any of the items stand out for you.

1. Low Fitness

This tends to be the number one contributor to cramps, in my opinion. Low fitness means inadequate endurance and/or athletes attempting to produce speeds on race day beyond what they used in training.

2. Dehydration

This is a tricky one and not straightforward. If there was humidity, that may have played a factor too. Heat and humidity can contribute to dehydration. Dehydration is thought to be a major cause of cramping. You don't mention your fluid consumption rate, but that may have been a problem.

3. Sweat Rate

Heat and humidity affect sweat rates and athletes should slow pace accordingly. Usually, if people try to keep the same pace as they do in cooler temperatures, they often cramp.

This may be due to dehydration and/or the loss of electrolytes. If you're not acclimatized to the heat and humidity, you'll lose more electrolytes in your sweat. Your supplement rate of electrolytes used in training in Colorado's cooler temperatures may not have been enough for Wisconsin.

Also, some of you may be "champion sweaters" and have more trouble staying hydrated than others. Your fluid consumption rate may have been fine in training, but not enough on race day.

4. Drinking Too Much Water

In an effort to stay well-hydrated before the race, some athletes drink water in the days before an event—and lots of it. If they get carried away, too much water ends up diluting electrolytes, or pulling them out of the body pre-race.

These athletes go into race day low on electrolytes. Drink enough fluids to keep urine a straw color, but not clear. Some people recommend drinking "plenty of" electrolyte drinks in the days before a race. I'm not convinced that's a good strategy and may leave you feeling bloated.

5. Racing on a New Course

If athletes train on flats and do a very hilly event, or vice versa, it seems to contribute to cramping.

6. Electrolyte Deficiencies

This also includes an imbalance in the normal diet. The term "electrolytes" includes sodium, magnesium, potassium and calcium. There is some belief that if your diet is low in magnesium and/or potassium that this leads to cramping. Find foods rich in magnesium and potassium to be sure you are consuming foods rich in these electrolytes.

Let me know if you think any of these six causes of muscle cramps may have been a problem for you.

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Gale Bernhardt was the USA Triathlon team coach at the 2003 Pan American Games and 2004 Athens Olympics. Her first Olympic experience was as a personal cycling coach at the 2000 Games in Sydney. She currently serves as one of the World Cup coaches for the International Triathlon Union's Sport Development Team. Thousands of athletes have had successful training and racing experiences using Gale's pre-built, easy-to-follow cycling and triathlon training plans. Let Gale and Active Trainer help you succeed.

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