What is exercise-induced cramp?
Exercise-induced cramps happen in muscles that are normally under your control, called skeletal muscles. But during a cramp, your muscle contracts strongly without you wanting it to, and it can be hard and tender.
Cramps are usually quite short-lived and they can stop as suddenly as they start. But sometimes, the pain and tenderness can last for several hours after the cramp has stopped.
Although any muscle can go into spasm, muscle cramps after exercise mostly affect:
- your calf muscle (gastrocnemius)
- the muscles in your foot
- the group of muscles in the front of your thigh (quadriceps)
- the group of muscles in the back of your thigh (hamstrings)
What causes exercise-induced cramp?
We don’t always know what causes muscle cramps during exercise, but there are two possible causes.
The most recent theory is that exercise-associated muscle cramps are due to muscle tiredness (fatigue).
Another, older idea is that cramp is due to dehydration and low levels of minerals called electrolytes in your body. But the evidence to support this idea isn’t conclusive.
It may be that exercise-induced cramp has different causes in different situations, or that several things work together to cause cramps.
You’re more likely to get exercise-induced muscle cramp if you:
- do endurance sports, such as marathon running
- take part in team sports, such as rugby
- work physically hard or exercise in hot, humid conditions
How do I stop exercise-induced muscle cramp?
You should stop working out if you have a muscle cramp, and gently and slowly stretch the affected muscle. Hold it in a stretched position for up to 30 seconds – aim to feel the muscle relax. You may find it helpful to do this stretch a couple of times.
Try to rest and give your muscle time to recover, or the cramp might return. You might need to reduce the intensity and how long you exercise for until you can exercise without cramp.
If you feel pain for more than eight hours after the cramps stop, see a physiotherapist to rule out an injury. If you have continuous cramps, a GP can help determine if you have an underlying issue.
How can I avoid exercise-induced cramp?
Because no one knows exactly what causes exercise-induced muscle cramp, it’s not certain what the best way to prevent cramp might be. But here are some things that may help.
Warm up and stretch
Although there’s no proof it will work, warming up and regularly stretching your muscles may reduce your chance of cramps.
It’s also helpful to keep your level of general fitness up and to set realistic goals. Slowly building up your fitness and strength allows muscles to adapt, without feeling too overloaded.
Try to get enough rest and build in some recovery sessions if you’re following a training plan. This can help to avoid fatigue, which is a possible cause of cramps.
It’s always important to stay properly hydrated when you exercise. You should drink enough water before, during, and after exercise – especially if the weather is hot or humid.
You can tell if you’re dehydrated by the colour of your pee (urine). The infographic below shows how to do this.