The Dangers Of Dehydration In Sports

Dehydration is a natural occurrence in the body when you do intense workouts such as endurance cycling, marathons, boxing, powerlifting, MMA, or professional athletics training. It results in a higher sweat rate than other sports activities especially when you do these exercises in hot and humid weather.

Studies show that dehydration impairs an athlete’s performance and causes illness and even death.  It’s important then to understand the dangers of dehydration in sports. You may be interested to know what happens when you’re dehydrated and how it affects your performance. Further, it’s vital to know the best ways of prevention and first aid treatment.

What Happens When You’re Dehydrated?

The body’s internal temperature of 37°C increases naturally through exercise. At the start, this aids in your performance because it facilitates the flow of blood to provide oxygen and nutrients to your muscles. When it reaches above 38.8°C, there’s a significant loss of the body fluid, and you feel the drop of your performance level.

What happens when the body temperature reaches more than 38.8°C? In this condition, the body needs to work more to cool itself. So, it diverts the blood to the skin to provide the body with water to lower the temperature. The water from the blood goes out through the sweat glands, then evaporates and cools you down in the process.

Excessive sweating decreases the amount of blood that carries oxygen to your working muscles. The brain tissue fluid also decreases which reduces brain volume momentarily thus affects cell functions. Without replacing the lost fluid, your blood becomes thicker; more concentrated which triggers the kidney to retain water.

Your heart pumps harder when your blood is thicker and concentrated.  It takes more effort on its part to circulate the blood throughout the body and compensate for the lower volume. Your heart rate increases evident by your quicker pulse. Your cardiovascular system works overtime when you are dehydrated.

Studies show that chronic extreme exercise training and competing in endurance events can lead to heart damage and rhythm disorders. When dehydration continues, the cells begin to shrink and malfunction due to water and electrolytes lost. The body tissues dry out, and blood pressure drops. Dehydration can also damage other internal organs such as the brain, kidney, and liver.

How Dehydration Affects Your Performance?

The body responds to dehydration by stimulating the thirst centers of the brain. The brain prompts you by making you thirsty. It is important to understand that when you feel the sensation of thirst, you’re already dehydrated. If your intake is not enough or you fail to replenish the lost fluid, the body will again respond by decreasing sweat and producing less urine.

At 1%, a mild stage of dehydration, there is an effect on your mood, attention, memory and motor coordination.  At 2%, you can feel a considerable decline in your performance. You’ll start to feel increased fatigue, reduced endurance, symptoms of heat illness and declining motivation.

Symptoms of mild to moderate dehydration include thirst, headache, dry mouth, muscle cramps, reduced sweating, low urine volume, and weakness. They can be reversed or put back into balance by rehydration. So, it’s a health requirement for athletes to have water and sports drinks intake before and during workouts and competitions.

At 3% or more, you’re in a dangerous condition which may fall into the severe stage of dehydration where the body’s electrolytes become very deficient. Symptoms include dizziness, rapid heartbeat or palpitations, nausea, vomiting, confusion, lethargy, seizure, shock and loss of consciousness.

In hot weather athletic events, you can be severely dehydrated which lead you to suffer from heat-related illness such as heat exhaustion, heat cramps, heat stroke, heat-induced coma or even death.  You can lose as much as 10% fluid in the heat which is a very dangerous level to encounter, ultimately becoming life threatening.

In the Tel Aviv 2013 half marathon, the temperature soared as high as 35°C. Dozens of runners were victims of dehydration and heat stroke. A total of 50 participants received treatment and 32 were taken to the hospitals, some unconscious and on a respirator. One runner collapsed along the course and was later pronounced dead in the hospital.

How To Prevent And Treat Heat-Related Illness?

Dehydration is manageable and preparation is the best prevention. To minimize fluid loss to not more than 2% of your body weight is a good rule. Aside from rehydrating, there are effective preventions for a heat-related illness which include:

  • Acclimatization and proper training for the heat.
  • Wearing of light colored, loose fitting, and one layer clothing.
  • Use a running belt to carry water bottles (find more info at com/best-running-belt)
  • Understand your body metabolism, know when and how much to hydrate.
  • Recognize early warning signs of dehydration and heat-related illness and respond to those symptoms immediately.
  • Have a competent medical staff to monitor your physical condition during workout and competition.
  • Hire a professional trainer or coach to measure the intensity of your workouts versus your tolerance.
  • Avoid high-intensity workout or training during the warmest part of the day otherwise, conduct it in an air-conditioned area.
  • Limit intensity and duration of exercise then gradually increase to allow the body to adjust to a high environmental condition.
  • If you feel weak or muscle cramps, stop the activity and cool down.
  • If you’re taking medication, check with your doctor if it has an adverse effect on your training. Some medications are diuretics which increase the passing of urine.
  • If you have medical conditions, you should undergo a medical evaluation before the start of a workout or competition.

Heat stroke is a life-threatening emergency. Call or ask someone to call for medical assistance. It usually occurs above 40°C when the body fails to regulate its temperature. This condition is called hyperthermia in severe dehydration cases when the body produces or absorbs more heat than it dissipates.

Before the onset of heat stroke, you can feel symptoms such as muscle cramps, exhaustion, and profuse sweating. When heat stroke strikes, there are changes in the mental status of the athlete who may have fainted and in a coma. While waiting for paramedics, you can administer first aid immediately:

  • Remove the athlete from the heat and get him to a shaded area or an air-conditioned building.
  • Remove constricting clothing or layers.
  • Monitor body temperature and cool down the athlete rapidly by cold water immersion, cold water sponging or placing cold towels over his whole body.


The more you exercise and train the more you have to be aware of your body’s hydration needs. Always be prepared and ideally talk to a coach, personal trainer or dietician to come up with an ideal plan for training sessions and competitive events.

Taking regular small sips of water every few minutes will go a long way towards helping your body perform at optimum levels.

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I think I met everyone involved in this site through Little League where our kids have been involved over the years. I’m one of the many coaches, and have an absolute passion for everything to do with baseball.

Ever since I got my first baseball card at about 5 years old, I’ve been addicted to all types of baseball statistics. The others keep winding me up when I give them the exact numbers from past seasons and games. Maybe it’s a super-power or maybe I’m just a bit too much of a nerd.

Coaching young kids and seeing them develop the same passion for the game is just so much fun, that it literally is the highlight of my week. I’ve met so many parents in our community this way, and it’s wonderful seeing these young kids growing up with the sport.

Anyway, I contribute on this site for anything baseball related as well as some fitness tips for kids and adults. I’ve done quite a few courses on coaching kids and adults and have learned so much over the years that I want to share with a much bigger audience.

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