dehydration and cramp

Does Dehydration Cause Cramp?

Mike Walden

Yes, dehydration can be a common cause of muscle cramps. When you become dehydrated, your body loses fluids. As a result, your blood volume decreases. However, you also lose electrolytes, such as sodium, potassium, magnesium, and calcium. These are minerals essential for proper muscle function. Therefore, muscle cramps may occur due to electrolyte imbalance.

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Cramp is when your muscles involntarying contract or go into spasm. It is a painful condition, which may result in muscle damage. It is however, important to note that the exact causes of cramp is still an area of ongoing research, and additional factors involved.

What is dehydration?

Dehydration occurs when your body doesn't have enough fluids. This may happen from:

  • Inadequate fluid intake.
  • Sweating too much.
  • Prolonged exercise.
  • Medical conditions.

When you're dehydrated, your muscles may not have the necessary electrolytes to function properly. As a result, they contract involuntarily resulting in muscle cramps.

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Preventing Cramp from dehydration

To prevent muscle cramps caused by dehydration, make sure you drink fluids throughout the day. This is especially important during periods of physical activity in hot weather. It sounds simple and it is!

Drink before you get thirsty

Thirst is your bodies natural way of telling you to drink fluids. However, by the time it gets round to telling you that you may wish to quench your thirst with an ice cold glass of water, it is too late. You are already dehydrated by then. This is why it is important to take on fluids regularly and before you get too thirsty.

If you are on a long race or walk where stopping is not an option then a hydration pack or vest is ideal for taking fluids on the move.


Additionally, consume food and/or drinks that contain electrolytes because these help replenish the essential minerals and help prevent cramping. This is probbly not so important if you are running for less than an hour in normal temperatures. You get enough salts and minerals from your diet.

However, if you go much longer, especially in hot conditions then you may need to top up the electrlyte levels with an electrolyte drink. No need to spend a fortune, putting a little salt into some orange squash can work.

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Other causes of Cramp

In addition to dehydration, other factors that are thought to cause muscle cramps include overuse of muscles, poor stretching, nerve compression and some medical conditions.

Important: if you're experiencing frequent or severe muscle cramps, consult with a doctor to rule out underlying medical issues which cause Cramp.

Evidence for Cramp and dehydration

These scientific studies investigate the causes of cramp:

Miller, K.C., Mack, G.W., Knight, K.L. et al. "Reflex inhibition of electrically induced muscle cramps in hypohydrated humans." Med Sci Sports Exerc. 2010; 42(5): 953-61. This study explores the relationship between dehydration and muscle cramps. It found that dehydration increased the susceptibility to muscle cramps and that the reflex inhibition of cramping was impaired.

Schwellnus, M.P. "Cause of exercise-associated muscle cramps (EAMC)–altered neuromuscular control, dehydration or electrolyte depletion?" Br J Sports Med. 2009; 43(6): 401-8. This review article examines various theories regarding the causes of exercise-associated muscle cramps (EAMC), including altered neuromuscular control, dehydration, and electrolyte depletion. It discusses the available evidence and proposes that EAMC is likely multi-factorial.

Miller, K.C., et al. "Independent and combined effects of dehydration and hyperthermia on cardiovascular responses to exercise." Scand J Med Sci Sports. 2010; 20(1): 53-61. This study investigates the independent and combined effects of dehydration and hyperthermia (elevated body temperature) on cardiovascular responses during exercise. It discusses the potential influence of these factors on muscle cramps.

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