DID YOU KNOW? Studies have shown that drinking pickle juice can help relieve exercise-induced cramps
Muscle cramps What causes these unexpected and painful spasms?
Types of cramp Apart from being an inconvenience, cramps are generally harmless. However, if they persist for more than 15 minutes, or reoccur regularly, they may be a symptom of an underlying problem. Leg cramps can be divided into two categories: idiopathic or secondary. Idiopathic leg cramps seemingly happen for no reason, like those that occur just as you’re drifting off to sleep. Secondary leg cramps are related to pre-existing conditions or particular activities, such as infections, neurological disorders, strenuous exercise or dehydration. Pregnant women may also become vulnerable to cramps, as the weight of the growing foetus puts extra strain on their legs.
Receptors within muscles and tendons constantly monitor the body’s movement and position. These receptors send reflex signals (which bypass the brain) to protect the muscles from potential damage. One reflex encourages muscle contraction, to prevent overstretching, while the other promotes relaxation to control tension. These reflexes are normally balanced, but can be disrupted so that the contraction signal overwhelms the relaxation one, resulting in the unexpected, intense and painful muscle spasm of cramp.
Even elite athletes can be floored mid-stride by cramp
They are often associated with exercise, but cramps can also strike when you least expect them. According to the NHS, 75 per cent of leg cramp cases occur during sleep. It’s the ultimate in rude awakenings.
What causes cramp? Contract
The leading theory suggests that disrupted nerve signals may be to blame
Relax
A delicate balance Muscles are protected from damage by reflexes. One encourages contraction to prevent overstretching, while another promotes relaxation to control muscle tension.
Proprioreceptors
Unconscious action Reflex signals travel through the nerves via the spinal column, bypassing the brain. This results in a quick action that you have no control over.
This class of receptors detects and responds to movement and changes in your body’s position.
The best way to ease idiopathic cramps is by stretching and massaging the affected muscle
Relax –
Spine
Contract ++
Cramp strikes When the contraction reflex overloads the relaxation one, the muscle contracts sharply, causing intense pain.
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Calf muscle The muscles of the calf contract and relax to lift and lower the heel when walking, running or jumping.
Muscle spindle These receptors within the muscles send signals that encourage contraction when stretched.
Golgi tendon organ Located on muscle tendons, these receptors send signals that encourage the contracted muscle to relax.
How It Works | 045
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ramp occurs when your muscles involuntarily contract very quickly and do not relax again straight away. These sudden spasms commonly affect the calves and last just a few seconds, but can persist for 15 agonising minutes or more. Normally, your calf muscles contract to raise your heels and relax to lower them, allowing you to walk, run and jump. However, during a cramp these muscles contract tightly and unexpectedly, leaving you unable to control them until the contraction subsides. The affected muscles remain tense and painful while they refuse to relax. Despite being such a common experience, nobody knows exactly what causes these random contractions. It’s thought that excessive strain on the muscles or a restriction in blood supply could be contributing factors, but one of the most prevalent theories is that cramps are caused by abnormal nerve activity.