Calf Cramps

Written By: Chloe Wilson, BSc(Hons) Physiotherapy
Reviewed by: KPE Medical Review Board

Calf cramps occur when the muscles suddenly and involuntarily contract or tighten and then won’t relax. 

Leg cramps can be extremely painful and may last for anything from a few seconds to several minutes, and there may be ongoing discomfort in the affected muscles for a few hours after calf muscle cramps subside.

In some instances there may be visible or palpable hardening in the muscle.

In most cases, leg cramps are completely harmless and settle down quickly, but they can be a sign of an underlying medical problem or electrolyte imbalance.

Cramp, often referred to as Charley Horse, typically affects the calf muscles, gastrocnemius and soleus, but can occur throughout the leg or in the foot.

Muscle cramps typically occurs at night time, after exercise or during pregnancy but can develop for no obvious reason.

Factors such as low energy, over training, increased intensity or duration of exercise and exercising in hot, humid environments leads to increased activity in the muscle spindles (the sensory receptors in muscles) and decreased activity in Golgi tendons (which control the tension in a muscle).

This all alters the neuromuscular control resulting in Charley Horse. Over-exertion also reduces the muscle’s oxygen supply and increases the amount of waste product in the muscle.

Calf cramps are a common problem during pregnancy, particularly in the second and third trimesters. The exact cause is unknown but is thought to be due to

• Additional Weight: which places extra strain on your muscles
  
  
• Changes in Circulation: Your growing uterus puts more pressure on blood vessels affecting the circulation in your legs
  
  
• Altered Levels of Nutrients & Salts: the baby takes what it needs from your bloodstream which can leave you slightly short of what you need. Low magnesium levels are thought to be associated with increased risk of calf cramps in pregnancy

Problems in the nerves can lead to calf cramps. The most common neural causes of calf cramps are:

• Peripheral Neuropathy:this is where there is damage to the nerves of the leg meaning the signals passing between the brain/spinal cord and the muscles are affected. This can affect the control and co-ordination between the agonist and antagonist muscles resulting in calf cramps
  
  
• Spinal Stenosis: Narrowing of the spinal canal places pressure on the nerves in the spine which can cause a cramp like pain in the legs. Pain tends to get worse with walking and may ease by bending forwards slightly as your walk e.g. leaning on a shopping trolley as bending increases the space in the spinal canal thus taking the pressure off the nerve.

Both of these can causes calf cramps and nerve pain in the feet and may be accompanied by tingling, numbness and/or weakness. Find Out More >

If your body loses too many fluids from sweating or dehydration, there is a drop in fluid and salt levels. This can lead to a loss in blood volume and resultant reduction in the oxygen supply to the muscles, and electrolyte imbalance, both of which can trigger muscle cramps.

This particularly affects athletes training in hot, humid conditions and those who wear full equipment such as American Football players. Excessive alcohol consumption and regular smoking also increase the risk of dehydration.

When playing sport or exercising, it can help to drink specially formulated sports drinks which contain the right combination of electrolytes to help prevent dehydration and cramping. 

Usually, movement is voluntarily, e.g. if you want to bend your elbow, you brain sends messages to the muscles in your arm telling the biceps (agonist) to contract and shorten and the triceps (antagonist) to relax and lengthen.

With cramp, there is an involuntary contraction of the muscle which you can’t control.

Calf muscle cramp typically strikes during or after exercise, usually due to muscle fatigue, or at night-time (known as nocturnal cramps) due to inactivity or sudden movement.

Calf cramps can develop in two ways, either the agonist contracts too hard and can’t then relax, or the antagonist fails to relax correctly and the muscle spasms. 

During An Attack: Stretch the calf muscles, hold the stretch until the muscle completely relaxes and any tension or hardness in the muscle has gone. This may take a few minutes. A good way to do this is to sit up with your leg stretched out and pull your toes up towards you. Alternatively, walk around on your heels (tiptoes lifted) for a few minutes

To Prevent Attacks: Calf stretches done regularly help the muscle to lengthen and can reduce the prevalence of calf cramps. Visit the calf stretches section for a range of exercises that can help

Muscle fatigue is a common cause of cramp, and this often comes about due to inappropriate training. We’ve all done it – decided one day we want to get fitter, or to enter a race and we suddenly up our exercise. We may train harder, longer or more often. But the body takes time to get conditioned.

The best advice is to follow the 10% rule – this means you should increase your activity levels by no more than 10% per week. This applies to distance, duration and speed. This gives your body time to adapt and greatly reduces the risk of injury or of developing calf cramps. Also, make sure you warm up and cool down properly when you exercise.

It also helps to improve the strength and endurance of the calf muscles so they can work more effectively so incorporate some strengthening exercises into your routine too.

Always keep yourself adequately hydrated, particularly when exercising. Drink plenty of water – the amount you need will depend on things like your age, weight, exercise level and your environment.

You may also want to try sports drinks which also contain electrolytes to help prevent imbalance.