Don’t Drink the Pool Water (Coaches’ Corner #7)

admin Coaches' Corner

By Dylan Otruba, Coach, MV1 water bottles

Now that we’re into the hot part of summer, and the hard part of training, it’s probably a good idea to touch again on the importance of hydration in swimming. Dehydration not only makes it harder to train effectively, it’s actually quite dangerous, especially during intense workouts in hot and humid pools. The following information is adapted from

One of the biggest threats to a swimmer’s performance, safety and health is dehydration. Dehydration is an illness which causes extreme electrolyte imbalances in the body. It occurs when you do not take in enough fluids to replace what have been lost through sweat and urination. While dehydration is a danger during any sport of physical exertion, it is more so during swimming. This is true for two reasons. First, when you exercise, you sweat. When you are in the water swimming, you do not realize that you are still losing fluid. Second, because you are surrounded by water, your brain is tricked to think you have all the fluid you need, and does not signal your mouth and throat to be thirsty.

Fluid Intake Requirements for Swimming

Dehydration can contribute significantly to fatigue and can be detrimental to swimming performance – not only physically, but mental skills such as focus, technique skills, judgment and decision making can also be adversely affected.

Here are some key hydration points to consider:

  • In general, to determine how much water you should be consuming on a daily basis, divide your body weight by half. That is the amount of water in ounces you should be consuming daily without exercise.
  • Two hours before exercise, swimmers should consume half a litre of water or a sports drink to help hydrate them ahead of time.
  • Swimmers should always bring a water bottle with them to training sessions.
  • Long-term, moderate to intense activity of 30 minutes or more requires periodic rehydration, such as a quarter of a litre every 20 minutes.
  • Post-workout hydration is important to recovery.

Muscle Cramps are Symptoms of Improper Hydration or Electrolyte Imbalance – Other Warning Signs

If you are feeling thirsty, you are already somewhat dehydrated. This is especially important to keep track of at swim meets!

The warning signs of dehydration include:

  • Thirst
  • Muscle cramping
  • Headaches
  • Dry mouth
  • Weakness
  • Unclear thinking
  • Fatigue
  • Dark yellow urine
  • Significant weight loss during exercise
  • Decrease of sweat during exercise

Water Conditions Impact Hydration Needs of Swimmers

Once the body starts to become dehydrated, it can’t function at its full capacity and as normal metabolism becomes impaired, your health and physical performance is at risk. Dehydration risks increase during certain water conditions.

  1. Cold Water Hydration. Surprisingly, dehydration is also a cold water hazard. Our body’s metabolism is revved up more so in cold water as the body strives to maintain a health core body temperature. More hydration is needed when swimming in cold water.

The onset of dehydration is often the cause of hypothermia. Hypothermia is very possible during endurance swimming or long pool sessions in cold or cool water.

  1. Warm Water Hydration. The debilitating effects of heat stress on the ability to perform prolonged strenuous exercise are well-established. During exercise in a hot environment, a substantial rise in body core temperature is often linked with the onset of fatigue and dehydration. Fluid replacement before and during prolonged swimming in the warm water has been shown to be effective in reducing the elevation of body temperature and in extending swimming endurance capacity. Long swims in a wetsuit in too warm water can cause the body to overheat more quickly.

When swimming in very warm water, the combination of the external heat and the internal heat produced from the exercise, heat within the body can build causing hyperthermia which is having a core body temperature that is too high. Maintaining good hydration can reduce the onset of hyperthermia as good hydration enhances sweating which acts to cool core body temperatures.