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Byline: DR ALI

I suffer excruciating cramps in my legs at night, to the point that I almost hate going to bed. Do you have any tips please?

ACramps occur because of muscles contracting. The muscles in your legs are part of the skeletal muscle system, which generally contracts at the command of the brain, hence they are called voluntary muscles.

Sometimes, however, skeletal muscles also act involuntarily. For example, with the diaphragmatic and intercostal (between the ribs) breathing muscles, we can inhale, exhale and hold our breath voluntarily, and breathe involuntarily. Similarly, there are times when voluntary leg muscles can contract involuntarily, as you are experiencing.

Skeletal muscles consist of large fibres that can be up to 12 inches long.

Muscles carry out heavy-duty work, so they are equipped with specific cellular power stations called nuclei and mitochondria, which are capable of converting glucose into energy very rapidly.

The contraction of muscles is a complicated procedure: muscle fibres squeeze together because protein fibres lock into each other, rather like combs slotted together.

When the protein fibres unlock, the muscle fibres relax and lengthen.

Excessive muscle contraction, as in sports training, triggers the muscles to demand more oxygen than the body can supply through breathing. This oxygen deficit causes the formation of lactic acid, a by-product of when glucose molecules are only partially burnt off. Lactic acid is a major cause of cramps.

Calcium is also a factor as muscles need it to contract. If there is a shortage, the muscle goes into spasm and cramps up to avoid losing it. So people suffering from osteoporosis may suffer, as may vegans and vegetarians whose bodies can't absorb calcium because of the lack of vitamin D from animal fats in their diet.

Lack of sunlight, which is vital for our bodies to synthesise vitamin D, is another factor.

Also, if you are chronically constipated, the colon can't readily absorb calcium. This causes cramps in the leg muscles at night when the circulation of blood is sluggish. Being dehydrated (often a cause of constipation) is another risk factor for cramps, as are excessive sweating and severe diarrhoea.

Poor blood circulation may be the villain. Very active people who suddenly have to give up exercising, perhaps because of an accident, may experience painful cramps. This is due to muscular atrophy (wasting), where fibrous scar tissue grows around the previously active muscles, resulting in decreased blood flow.

Low levels of potassium and sodium, which are essential for good muscle functioning, are also implicated in cramps.

A lack of potassium may be caused by a poor diet, or by taking diuretics, which trigger the excretion of potassium.

The lack of potassium and sodium, which act as electrolytes on the surface of muscle fibres, leads to impaired response to nerve stimulation, so the fibres go into spasm erratically, causing a cramping sensation. …