Cramps are a common running and cycling injury, here’s how to avoid them

How to stop leg cramps

Leg cramps are painful muscle contractions and once they start, it’s hard to shake them (Illustration: Peter Greenwood)

It’s not known exactly what triggers cramp, but it’s more likely to occur in tired muscles, so poor fitness or exercising at high workloads increases the likelihood.

What you consume has an effect, too. “Dehydration may contribute to cramp especially when fluid and sodium losses are high,” says Claire Lane, Applied Physiologist and Sports Nutritionist for Team Bath.

“Sodium is involved in initiating nerve signals that make muscles contract. A deficit of sodium and fluid may ‘irritate’ your muscles, causing them to contract uncontrollably.

“Magnesium may be relocated in the body during exercise rather than lost in sweat, so a magnesium imbalance in relation to sodium and potassium may be involved.”

Cramp – symptoms

  • Sudden, intense pain in muscles, typically in the legs and feet
  • Involuntary shortening of muscles contorting the body e.g. toes curling with foot cramp


  1. Stay hydrated during exercise. Isotonic sports drinks help to replace sodium lost in sweat. In hot weather, sodium intakes of around 0.25-0.7 grams per hour may be necessary – aim to sip 750ml of energy drinks with electrolytes per hour when you’re really sweating.
  2. Allow adequate recovery and rest for muscles after hard training sessions. Balance your training, so follow a high intensity session with an easy session, and try to avoid back-to-back hard sessions using the same muscle group.
  3. Increase strength and fitness. Stronger, fitter muscles are more resilient to cramp. Be cautious when changing speed or intensity, especially during the later stages of exercise as fatigued muscles take longer to adapt.
  4. Warm up to prepare muscles, warm down to start the repair process and stretch to keep your muscles loose and flexible. It’s important to spend 5-10 mins on each of these processes, especially for tougher sessions and races.