How Dehydration Affects the Muscles

How Dehydration Affects the Muscles


Water is the most important resource for the body. When we don’t stay on top of our water intake, our bodies start to pay the price. These effects include fatigue, dizziness, headaches, etc. According to Mayo Clinic, “Dehydration occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions. If you don’t replace lost fluids, you will get dehydrated.” Water is one of our body’s 6 essential nutrients. Our bodies do not have the capacity to store significant volumes of water so we need to consume adequate amounts of fluids daily to hydrate every cell in our bodies.

Angelo Marsella MA, ATC, USAW, Director of Sports Medicine at Professional Physical Therapy, shared with us the importance of staying hydrated, and the best way to do so.

Generally the human body is made up of about 50-75% water. Water forms the basis of blood, digestive fluids, urine & perspiration, muscle function, bones and fat. Dehydration during training and competition may not only hinder acute exercise performance, but also delay recovery from a previous exercise bout. This is particularly relevant to athletes and practitioners because recovery is a critical component of performance, especially when multiple practice sessions or competitive events are performed within a short time period.


So… how much water do you need?

Intensity and duration of training, environmental condition (heat/humidity) and equipment (pads/uniform) all play a role in how much fluid is lost during activity. A good rule of thumb is that athletes should drink 16-24 fluid ounces of water within 2 hours prior to training. At 10-20 minutes prior to exercise consume another 7-10 fluid ounces of water. During practice, you should consume 6-12 fluid ounces every 10-20 minutes during training. After practice or training you should drink about 8 fluid ounces of water to re-hydrate your body and prevent any cramping.

Remember to listen to your body!  Your body will inform you if you’re dehydrated. If you’re dizzy, fatigued, nauseous, or cramping, stop exercising immediately. Get some water and rest to prevent your risk of injuries — these warning signs inform you that it’s time to re-hydrate.

There are several types of heat illness. They range in severity, from heat cramps and heat exhaustion, which are common but not severe, to heat stroke, which can be deadly.

Some tips to consider:

  • Hydrate before, during and after activities.
  • Clothing worn by athletes should be light colored, lightweight and protect against the sun.
  • Remove any unnecessary equipment, such as helmets and pads, when environmental conditions become extreme.
  • LISTEN TO YOUR BODY! If you feel any of the early signs of exertional heat stroke (headache, dizziness, confusion/disorientation, excessive sweating, fatigue, nausea and or chills), notify a coach, parent or medical professional at the event. Remove yourself from the activity, go to a shaded/air-conditioned area, and begin hydrating.
  • At the secondary school level, develop a heat acclimatization policy for the athletics program. This type of program is made to “recognize the threat posed by athletic exertion on warm or hot days, and take the needed steps to acclimatize student athletes,” as stated by the National Athletic Trainers’ Association.

It may sounds simple but the easiest way to ensure performance and protect your health is to stay hydrated during exercise. Studies have shown that a loss of 2% of body weight in fluids has been shown to have adverse effects in performance for adults and a mere 1% loss of body weight in children has the same adverse effects. When you’re exercising, make it a priority to pay attention to your water intake. This will help to keep your muscles in good shape and avoid injury.


If you’re experiencing any aches or pains during physical activity, schedule an appointment with a Professional physical therapist. To make an appointment, visit