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Why Do My Muscles Cramp?

Everybody has suffered from muscle cramps at some point in their life, whether it by while they were participating in recreational activities or while they were sleeping at night. Muscle cramps can happen at any time throughout the year, but studies have shown that they are twice as common during the summer than in the winter. Although there is no way to stop cramps from happening entirely, there are several things that can be done to help prevent them. Below are the main topics that will be covered:

  • What are muscle cramps?
  • What causes dehydration, and how does that affect the muscle?
  • How can we prevent muscle cramps?

Muscle Cramps

Before we can dive into what causes muscle cramps, we first need to understand what they are. A muscle cramp is a strong, painful contraction or tightening of a muscle that comes on suddenly and can last from a few seconds to several minutes. Muscle cramps usually occur in the legs and are often referred to as a “charley horse.” There are several different types of cramps, but the most common include fatigue and dehydration related cramps.

Fatigue cramps:

  • This occurs in overworked and tired muscles that can’t keep up with the demand for a particular activity.
  • If the muscle continues to be used, the body will react by tensing up.
  • It can occur during the activity or several hours later.

Dehydration cramps:

  • This occurs when the body does not have enough sodium or fluids.
  • More common in hot weather due to the increased amount of sweating.
  • It causes a greater loss of electrolytes, sodium, and fluids from the body.


First, what is dehydration? Dehydration is when more water is exiting the body than is going in. The first sign of dehydration is thirst, which occurs after you’ve already lost around 2-3% of your body’s water. Water accounts of 50-65% of an adult human’s body weight and varies based on age, activity level, and body composition.

If you have been outside during the past two months, then you probably noticed our body’s natural defense against the heat – perspiration. This process cools us down through evaporation of sweat on our skin, which depletes our body of fluids. Along with sweat causing a loss of fluids, it also causes the levels of electrolytes such as sodium and potassium to decrease as well.

Sodium is an essential electrolyte that helps maintain the balance of water in and around your cells, while potassium is key in helping to start and stop muscle contractions by relaying signals from the brain. If your dietary intake of sodium and potassium is not equal to the amount that is being depleted, it can cause a deficit of either one of those electrolytes.

Effects of Low Sodium Levels

  • Electrolyte and fluid loss cause water to move into cells from the surrounding area
  • Lack of water causes space around cells to contract
  • Contraction triggers a cramp that can occur in several muscle groups simultaneously

Effects of Low Potassium Levels

  • The brain cannot relay signals to muscles effectively
  • Causes uncontrolled and prolonged contractions known as cramps

What Can be Done to Help Prevent Cramps?

Even though we can never completely prevent ourselves from ever experiencing cramps, there are still steps we can take to help prevent the occurrence of them.

Stretching should be done before and after exercise or sports, along with an adequate warm-up and cool down in order to prevent overworked and tight muscles, which results in cramps. Good hydration before, during and after the activity is also important, especially if the duration exceeds one hour. The replacement of lost electrolytes, especially sodium and potassium, can also be extremely helpful in decreasing your chance of getting a cramp.

The current standard of hydration is 8 cups (64 ounces) of water consumed consistently throughout the day, but since proper hydration varies based on age, activity level, and body composition, each individual will have a varying recommended daily level of fluid intake based on their specific needs.

If you have more questions, or would like to speak with a physical therapist, click below to schedule a discovery visit with Buffalo Rehab Group.


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Pandey AK, Pandit A, Pandey BL. The Pathophysiology and Care of Exercise Related Muscle Cramps. Journal of Tropical Life Science. 2015;5(1):25-29.

Ruxton C. Promoting and Maintaining Healthy Hydration in Patients. Nursing Standard. 2012;26(31):50-58.

Stoppler MC. Muscle Cramps. MedicineNet. 2019.