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Mid-run muscles cramps can ruin a session or PB attempt. Here’s what causes them and, crucially, how to stop them from happening

Cramp is a neuromuscular issue, caused by a malfunction in a reflex between your muscle and spinal cord, think sports scientists. One of the motor neurons becomes excited, and isn’t turned off, constantly stimulating the muscle to contract – aka, cramp. We aren’t entirely sure what causes this, but local muscle fatigue seems to be an important factor. Here's how to treat, and prevent, mid-run muscle cramps – including the dreading calf cramps...

Preventing the local fatigue is your best path to preventing cramp. The secret is a combination of adequate training and ‘appropriate execution’, which comes back to pacing to match your training level. If you’re training to run a marathon in four hours, don’t nail the first 10 miles at 3:30 pace. It sounds simple, but is one of the hardest things in distance racing: don’t try to ‘out-run’ your training.

While there can be a handful of reasons you’re experiencing nagging calf pains, generally speaking, calf cramps happen because the muscles in the posterior chain, which include the glutes, hamstrings and calves, aren’t strong enough, and so the muscle goes into a spasm, or small contractions, if it’s pushed too hard, explains Jordan Metzl, M.D., sports medicine physician at Hospital for Special Surgery in New York. ‘Less commonly in the calf, cramps are due to nutritional issues such as hydration and electrolyte imbalances,’ he adds.

The received wisdom with marathon cramping is that it’s salt depletion that’s to blame. But a new study suggests a different candidate: a lack of strength training. Eighty-four marathoners agreed to undergo a series of tests before and after their race. Of these, 24% complained of cramping. Interestingly, their sodium and potassium levels were no different from the non-crampers, but their muscle biopsies were. The likely reason? The non-crampers were almost twice as likely to have included strength training in their build-up.

That’s not to say you shouldn’t pay attention to your hydration and sodium levels – you absolutely should – but it’s not necessarily the chief cause of muscle cramps.

While it’s tempting to just power through when you start to feel the pain, that’s not always a good idea. If the pain is only mild, it’s fine to try to shorten your stride and keep on running, explains Metzl. ‘If it feels more serious, I’d recommend pulling over and stretching it out,’ he says. Try stretches such as downward dog, a lunging calf stretch, or standing bent-over toe touches, depending on what you’re able to do without increasing the pain. Then you can try running on again.

Don’t obsess over stopping or losing valuable seconds – easing the cramp won’t just make those last miles more bearable, it will help to get you to the finish line quicker by enabling you to get back to a faster pace.

Given the important role that strength training seems to play in diminishing the likelihood of experiencing calf cramps, here are some calf-strengthening exercises worth trying:

Double-legged standing calf raises on a flat surface are your starting point. Do them first with the legs straight throughout and then with the knees bent throughout (so you’re ‘rolling’ forward as you lift the heels).

Aim for 3 sets of 20 reps each. Build to 40 reps.

Progress to single-leg raises using a step: have your support leg’s foot on the next step up, with 30-40 per cent of your body weight on it, while you perform full-range raises with the other leg.

Aim for 3 sets of 15 of straight leg/bent leg raises. Build to 25 each side.

You’re ready for single-leg raises with your full weight on the working leg. Start with 3 set of 15, building to 25 each side. Add challenge with a barbell or weighted backpack (aim for half your weight).

Do 3-5 sets of 8 reps, straight leg/bent leg.