Causes of Muscle Spasms and Cramps

Muscle Cramp Causes

Verywell / Laura Porter

Table of Contents
View All
Table of Contents

Muscle cramps and spasms happen when a muscle spontaneously contracts. The reason for this isn't well understood, but some researchers believe cramps and spasms may be related to muscle fatigue, muscle strain, or other factors like dehydration.

A muscle spasm or muscle cramp can cause minor discomfort to severe pain. You may even end up with a bruise in the location of the cramp.

This article discusses muscle cramps and muscle spasms, their possible causes, and what you can do to prevent them.

What's Happening When a Muscle Cramps

Most muscle spasms and cramps are involuntary contractions of a muscle. A serious muscle spasm doesn't release on its own and requires manual stretching to help relax and lengthen the shortened muscle.

Cramps can involve part of a muscle or all the muscles in a group. The most commonly affected muscle groups include:

Spasms and cramps can be mild or extremely painful. While they can happen to any skeletal muscle, they are most common in the legs and feet and muscles that cross two joints, such as the calf muscle.

Muscle cramps range in intensity from a slight twitch or tic to severe pain. A cramped muscle can feel rock-hard and can last a few seconds to several minutes or longer.

It is not uncommon for cramps to ease up and then return several times before they go away entirely.

Possible Causes of Muscle Cramps

The exact cause of muscle cramps is still unknown, but the theories most commonly cited include:

Other factors that have been associated with muscle cramps include exercising in extreme heat.

Because athletes are more likely to get cramps in the preseason, near the end of (or the night after) intense or prolonged exercise, some feel that a lack of conditioning may cause cramps.

Neuromuscular Control and Cramps

While all these theories are being studied, researchers are finding more evidence in favor of the "altered neuromuscular control" hypothesis. Some researchers think this may be the primary mechanism that leads to exercise-associated muscle cramping (EAMC).

According to this theory, muscle cramping is often related to muscle fatigue and results in a disruption of muscle coordination and control.

A 2018 review concluded that there was better evidence in favor of the neuromuscular hypothesis, and that there was only inconsistent evidence to support the dehydration and electrolyte depletion theory.

Muscle Cramp Treatment and Prevention

Cramps usually go away on their own without treatment. Until the exact cause of muscle cramps is known, it will be difficult to say with any confidence how to prevent them. However, these tips are most recommended by experts and athletes alike:

  • Stop the activity that caused the cramp.
  • Gently stretch and massage the cramping muscle.
  • Hold the joint in a stretched position until the cramp stops.
  • Improve fitness and avoid muscle fatigue.
  • Stretch regularly after exercise.
  • Warm up before exercise.
  • Stretch the calf muscle in a standing lunge with both feet pointed forward by straightening the rear leg.
  • Stretch the hamstring muscle by sitting with one leg folded in and the other straight out, foot upright and toes and ankle relaxed, leaning forward slightly, and touching the foot of straightened leg. 
  • Stretch the quadriceps muscle while standing by holding the top of your foot with the opposite hand and gently pull heel toward buttocks.

Most muscle cramps are not serious. If your muscle cramps are severe, frequent, constant or of concern, see your healthcare provider.


A muscle spasm is an involuntary contraction of the muscle. It can be very painful and can sometimes even leave a bruise on the skin.

The exact cause of muscle cramps isn't known for sure, but some researchers believe it may be related to muscle fatigue and a disruption in muscle control.

You may be able to prevent muscle cramps by stretching regularly, especially before and after exercise.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. The American Academy of Orthopaedic Surgeons. Muscle cramps.

  2. Jahic D, Begic E. Exercise-associated muscle cramp-doubts about the cause. Mater Sociomed. 2018;30(1):67-69. doi:10.5455/msm.2018.30.67-69

  3. Giuriato G, Pedrinolla A, Schena F, Venturelli M. Muscle cramps: a comparison of the two-leading hypothesis. J Electromyogr Kinesiol. 2018;41:89-95.

By Elizabeth Quinn
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.