A blog by runners. For runners.

Why muscle cramps happen — and how to prevent them


Most runners have experienced a muscle cramp or side stitch during a run or worse – mid-race. In fact, 4 in 10 distance runners have had a cramp pop up in their calves, quadriceps, or hamstrings during a race.

Experts aren’t positive why muscle cramps and side stitches happen. Dehydration and electrolyte imbalances used to take all the blame, but recent research says many other factors could be culprits, too.

Preventing muscle cramps
If you cramp up, there may not be a clear reason for the situation. But if you take several precautions, you’ll greatly reduce your risk for muscle cramps:

  • Hydrate well before and during runs. I know we just said dehydration may not cause all cramps. But that’s the thing – while fluid imbalance isn’t responsible for all cramps, it does cause some. (Read more about your fluid needs.)
  • Replenish with electrolytes, too. Your body needs more than water on runs longer than 60 minutes. Sip on sports beverages or use other mid-run fuel that contains vital electrolytes including sodium, magnesium, and potassium. There’s no magic formula for how much electrolyte replenishment you need and how often to take it in – it varies from runner to runner. The only way to figure out what works for you is through trial and error. If you’ve been cramping, take GU more often and see if that helps.
  • Train smart. Another theory is that cramping happens more easily to damaged or fatigued muscles. So, it makes sense that runners cramp up towards the end of a race. It’s OK to race all out, but make sure you train smart in the months leading up to it. Don’t overdo the speedwork, be sure to run easy on easy days, and taper well.
  • Keep muscles strong. Regularly lifting weights and doing plyometric exercises can keep muscles strong and stop them from fatiguing during a race.
  • Don’t go out too fast. We’re guessing you guys have heard this one before! Here’s another reason to keep it slow in the beginning of a run: going too fast out of the gate can spark cramps later on.

For side stitches
The above tips may also keep side stitches away. The tricks can help, too:

  • Take deep breaths. Breathe deeply from your diaphragm on every breath. Be extra mindful to do so during periods of intense effort. Side stitches may stem from shallow breathing. Always inhale through your nose and exhale through your mouth.
  • Time your eats. Some runners need to wait an hour or two after eating a meal before they can run comfortably. This is especially true if you eat a meal high in fat or protein. Try eating a light, carb-heavy meal pre-run and fuel up with more food when you’re done.

When a cramp strikes
The best thing to do when you feel a cramp coming on is to stop and stretch the muscle that’s cramping. Unfortunately, you may have to do this several times during a race. And if you happen to be in the vicinity of pickle juice, drink up! One study found that people who drank pickle juice stopped cramps quicker than those who drank water (here’s a yummy recipe for pickle juice popsicles).

Written by Jen Matz.