Dehydration can be serious! Hydration affects muscle performance and is an important component of injury prevention

hydration dehydration

Summer heat has arrived, which can make it difficult to stay adequately hydrated in the Midwest scorching heat and humidity. Dehydration is caused by an excessive loss of water from the body, and it not only affects performance due to fatigue, but also sets up any active person for an increased risk of musculoskeletal injury. There is a significant link that has been shown between dehydration and muscle injuries, and this is because muscles require fluids and electrolytes to function properly.

Potassium and sodium are two main electrolytes that muscles need for optimal performance and are lost from the body with sweating.

Sodium and potassium have a role in the muscles by flowing either in and/or out of the cells to cause a change in the electrical charge that result in a muscle contraction or relaxation.

A reduction in either of these electrolytes makes it difficult for the nerves to transmit the electrical signals needed for a muscle to work properly, which can lead to weakness, muscle spasms and impaired muscle timing/function, plus further results in poor movement patterns and slowed reaction times.

Dehydration also causes the blood to become thicker, which makes the cardiovascular system have to work even harder and your body to fatigue more quickly.

Research has shown just a three to four percent decrease in hydration can negatively affect muscle endurance and increases risk of injury. Muscle strains and sprains are common injuries in athletes and proper hydration not only acts to prevent these injuries, but also helps to speed up recovery from an injury when they do occur.

A recent study found dehydration negatively affects muscle control at the hip, knee and ankle with landing techniques leading to poor balance and poor sport-specific movements (Distefano, 2012). This produces abnormal stress on joints, ligaments and the muscles that stabilize the joints and can also cause a chain reaction resulting in dysfunction elsewhere in the body.

Dehydration signs include:

  • Extreme thirst
  • Dizziness
  • Confusion
  • Headache
  • Nausea/vomiting
  • Weakness/Fatigue
  • Decreased urine output/dark urine

Tips to avoid dehydration:

  • Drink ~16 ounces of fluids before exercise, 4-8 ounces for every 20 minutes of exercise following.
  • Weigh yourself before and after exercise. For every pound lost after exercise, consume ~16 ounces of fluids.
  • Wear light colored, loose fitting clothing.
  • Avoid overexertion, especially in hot and humid temperatures.
  • For intense activity, add electrolytes to water or drink fluids already containing electrolytes.

Hydrating before, during and after sports activities is an important component of injury prevention and recovery and an easy way to help prevent ongoing muscular issues.

New research has even shown it can help to decrease your risk of concussions, which has been a hot topic in sports the past few years. If you are dealing with recurrent muscle injuries, contact your local physical therapist who will perform a comprehensive assessment to determine the cause and best plan of action.

Stay hydrated, everyone!

Article by Jenna Stones, DPT. Jenna is a physical therapist and movement specialist at CORE Strategies Physical Therapy, Sport Performance & Medical Fitness in Overland Park.  The CORE team specializes in rehabilitation and performance training for clients of all ages and activity levels.  To learn more about CORE’s sport specific programs visit  Contact Jenna at

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