Leg, calf and foot cramps – causes and prevention

The leg muscles work throughout the day, responding to changes in load, temperature and body position, which is why their functioning depends on many small factors. The balance between tensing and relaxing the fibres requires efficient cooperation between the nervous system, circulation and electrolyte balance. Even minor disturbances in these areas can affect how muscles respond to stimuli and increase the risk of painful and uncontrolled spasms.

1. Proper muscle contraction
2. Pathological contractions
3. Preventing leg cramps
4. Diet for cramps
5. Supplementation

Proper muscle contraction

Skeletal muscle contraction is a natural process in which muscle fibres shorten and generate the force necessary to perform movement. Contraction begins when a nerve impulse from a motor neuron (a nerve cell that controls muscle function) reaches the muscle fibre and stimulates it to act. In response, an electrical signal travels along the entire fibre, opening calcium ion stores inside the cell. The released calcium ions activate the proteins responsible for contraction, allowing them to bind together and move.

The movement of these proteins requires energy, which is supplied by adenosine triphosphate (ATP). ATP is a molecule produced after the consumption and processing of primarily carbohydrates and fats. As long as the cell maintains high levels of calcium ions and energy from ATP is available, the fibre remains in a contracted state. When the nerve impulse stops, the calcium ions are quickly stored away again, the proteins cease to work together and the muscle relaxes.

Pathological contractions

Muscle fatigue

Involuntary and troublesome contractions of the calves and feet are most often the result of muscle and nerve excitability disorders, which cause the fibres to contract uncontrollably. One of the most common causes is muscle fatigue after prolonged exertion or after standing for many hours, when energy metabolism products accumulate in the muscle and irritate the nerve endings.

Water and electrolyte balance

Water and electrolyte imbalances also play an important role, especially low levels of magnesium, potassium, sodium and calcium, which are responsible for impulse conduction and proper muscle relaxation. When their concentration drops, the fibre may react excessively and contract despite the lack of a command from the nervous system. Dehydration is also an important factor, as it reduces blood volume and increases electrolyte concentrations in a way that disrupts signal conduction in the muscles.

"Just like dehydration, electrolyte imbalance can cause muscle cramps. In fact, dehydration itself can lead to electrolyte imbalance." Tomasz Maciołek - Physiotherapist and Trainer

Cold and pressure

For some people, painful and uncontrollable cramps occur at night when circulation is slower and changing the position of the legs can temporarily restrict blood flow to certain groups of fibres. Sometimes cramps develop when the limbs cool down quickly, as cold increases muscle tension and stimulates sensory receptors. The problem may also be caused by pressure on a peripheral nerve, for example, when the lumbar region is overloaded or when staying in an uncomfortable position for a long time, which temporarily disrupts signal transmission.

Pregnancy, medication, illness

In pregnant women, a common cause is increased strain on the legs, changes in fluid balance and a greater need for minerals. Certain medications can affect muscle and nerve function, including diuretics that reduce potassium levels, high blood pressure medications, statins, and some sleep aids. In some people, cramps are caused by chronic conditions such as neuropathies, thyroid disorders, or poorly controlled diabetes.

Other factors

Painful cramps also occur when the muscle is weakened due to inactivity or when the calves and feet are overloaded with repetitive movements. Sometimes the discomfort is associated with improper footwear, which changes the way the foot works, shortens the muscles and causes them to tire more quickly. Tension in the fascial structures can also have an impact, as limited tissue sliding increases the sensitivity of sensory receptors and facilitates the triggering of uncontrolled cramps.

Preventing leg cramps

The best-studied and safest way to prevent calf and foot cramps is to stretch the calf and hamstring muscles slowly every evening, as regularity reduces fibre tension and decreases their sensitivity to sudden stimuli. 

"Magnesium is often more effective in directly relieving cramps, especially those that occur at night. Potassium, on the other hand, is important for maintaining electrolyte balance and muscle health, especially during physical exertion." Łukasz Domeracki - MSc in Food Technology

However, stretching is not the only important factor here. Painful cramps can also be avoided by following an appropriate training plan that includes both endurance and strength training. Keeping your cardiovascular system in good condition can translate into better conscious motor (nervous) control of your muscles and their vascularisation. However, it is important to remember to gradually increase the intensity of your workouts and avoid sudden jumps in load.

It is also helpful to stay hydrated throughout the day, as fluids facilitate the proper conduction of impulses in the muscles. It is advisable to maintain a steady intake of minerals in your diet, especially magnesium, potassium and calcium. If you sweat a lot, are very physically active or follow a Western-style diet, supplementation may help. There is no evidence that coffee has any negative effects.

Estimated daily adult requirements for minerals affecting muscle contractions

Diet for cramps

In the case of cramps, a diet rich in magnesium, potassium and calcium is considered optimal. This could be a Mediterranean diet or DASH (Dietary Approaches to Stop Hypertension – a diet for high blood pressure), which are based on minimally processed foods such as nuts, seeds, whole grains, cocoa, leafy vegetables, bananas, tomatoes, potatoes, legumes, dairy products and water with a higher mineral content (highly mineralised).

Supplementation

Dietary supplementation may be useful for people who are highly exposed to physical exertion and mental stress, or who struggle with sleep and anxiety disorders, as well as for pregnant women. Particular attention should be paid to magnesium, which inhibits excessive nervous excitability. Magnesium citrate or diglycinate are most commonly used in doses not exceeding 200-300 mg per day.

Sources:

• Hawke, F., Sadler, S. G., Katzberg, H. D., Pourkazemi, F., Chuter, V., & Burns, J. (2021). Non-drug therapies for the secondary prevention of lower limb muscle cramps. The Cochrane database of systematic reviews, 5(5), CD008496. https://doi.org/10.1002/14651858.CD008496.pub3
• Coppin, R. J., Wicke, D. M., & Little, P. S. (2005). Managing nocturnal leg cramps--calf-stretching exercises and cessation of quinine treatment: a factorial randomised controlled trial. The British journal of general practice : the journal of the Royal College of General Practitioners, 55(512), 186–191.
• Hallegraeff, J. M., van der Schans, C. P., de Ruiter, R., & de Greef, M. H. (2012). Stretching before sleep reduces the frequency and severity of nocturnal leg cramps in older adults: a randomised trial. Journal of physiotherapy, 58(1), 17–22. https://doi.org/10.1016/S1836-9553(12)70068-1
• Barna, O., Lohoida, P., Holovchenko, Y., Bazylevych, A., Velychko, V., Hovbakh, I., Bula, L., & Shechter, M. (2021). A randomized, double-blind, placebo-controlled, multicenter study assessing the efficacy of magnesium oxide monohydrate in the treatment of nocturnal leg cramps. Nutrition journal, 20(1), 90. https://doi.org/10.1186/s12937-021-00747-9