In this episode we're going to talk about dehydration effects on athletic performance. Dehydration decreases mental and physical performance both on the field and in school in dramatic ways. Not staying hydrated, for example, cut performance by nearly 50% in laboratory studies for patients who were just walking!Dehydration affects the body and the mind in many ways that extend well beyond the soccer field. Listen to find out how dehydration decreases mental performance in school, decreases endurance, and can lead to significant medical problems.
What's the problem?
One study I read showed that 70% of high school football players were dehydrated before practice even started. This affected not only their performance on the field, but also in school, and had a significant negative impact on their health. A strong correlation exists between hydration and learning performance - both in the sports environment and in school. It turns out, our brains and even our immune system needs plenty of water too!
Water makes up 50-65% of the average athlete's body weight. When we're dehydrated, it's kinda like driving a car without oil. The lack of proper hydration for lubrication, circulation of blood (for thermal regulation and nutrient distribution) makes it difficult for our bodies and brains to function, and that leads to early fatigue.
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What are the general effects of dehydration on athletic performance?
Dehydration creates the following conditions:
Reduction in blood volume (blood flowing around the body)
Decreased skin blood flow (meaning we can exchange heat efficiently in the cold or the heat) Think about the radiator in your car.
Our core temperature goes up
Decreased sweat rate
Increase rate of muscle glycogen use (our muscles burn sugar faster) which leads to fatigue
When thinking about the general effects of dehydration on athletic performance, it helps to know that these effects are compounding. As our core temperature goes up, for example, stress on the body increased, which increases the demand for more "coolant" water.
Performance test results
Let's look a little closer at the effects of dehydration on athletic performance. In a study referenced below in the resources section, scientists took a group of subjects through a test. The asked each of them to complete a 140 minute walk. In the table below, you can see the results of that test in terms of completion rates.
Dehydration %
Completion Rate
Comments
3% Dehydrated
100%
Everybody completed 140 mins
5% Dehydrated
88%
12% could not complete the test
7% Dehydrated
25%
75% stopped after 64 minutes!
When subjects were dehydrated to 8%, they were only able to complete only 55 minutes of the test. This should speak volumes about the effects of dehydration on athletic performance!
Emergent effects of dehydration
Dehydration is well known for creating additional, more obvious effect on athletic performance and on our well being. If left untreated, this progression can lead to hospitalization and even death. Conditions like heat exhaustion and heat stroke might be in your athlete's future if we're not watching for the warning signs such as:
Headache
Thirst
Muscle cramps
Weakness
Nausea
Irritability
And even goosebumps!
It's important to remember that athletes are going to dehydrate even further from wherever they start activities like practices and games. So if an athlete shows up already 3% dehydrated, they can be 5-7% dehydrated by the end of the activity. Remember that our hydration status changes along the way. At the end of a practice or a game, for example, our athletes can be in pretty bad shape if they started off dehydrated in the first place.
Being dehydrated also reduces out ability to tolerate high core temperatures and it reduces maximum cardiac output. This means the heart can not pump as much oxygen and fuel deliveri...
