Dehydration decreases sports performance

Water is a vital component of our body composition. It makes up 50-75& of the body and it needs continual supply to help with metabolic functions. Our requirements depend upon a number of genetic factors including height, age, body composition and metabolism. It is also influenced by the weather and activity levels. Fortunately for us we do not just have to consume plain water to reach out requirements. What most people do not realise a number of foods are also comprised almost entirely of water (dairy, fruits, vegetables) and  consuming a wide variety of these foods will also help attain requirements. Depending on the types of foods you consume, 20-30% of requirements can come from food; the rest is needed to be consumed from water/milk/tea/coffee.

Hydration in regards to Sports Performance:

Hypo hydration is when your total body water is below normal. It increases perception of fatigue, elevates your heart rate and body temperature and also decreases mental function for skill work and motor control.

Most types of exercise are adversely affected, especially when completed under hot conditions. For example, did anyone watch the Games athletes compete in Murph? How many athletes suffered from heat stroke or severe dehydration? If you were to weight the athlete before and after the workout, I guarantee they would have lost in excess of 2% body weight (BW) during the event. (for example >1.2kgs for a 60kg athlete). For dizziness and mental/physical deterioration as these athletes suffered they probably would have lost ~10-15% of BW. If they were consuming fluid appropriately during the event, would they have been so fatigued? Nutrition and hydration is so vital, especially for long bouts of exercise or training. For other athletes who are around the 2-4% mark, drinking regularly throughout exercise can prevent any decline in concentration or skill level. Not only this but it will improve perceived exertion, but it will also prevent elevations in heart rate and body temperature.

This signifies its importance in giving an athlete a greater edge of their component and should be something to monitor. Even if you are not an elite athlete, for those who are looking to enhance the own performance in training and increase their capacity to do work, why not ensure you are hydrated. Training sessions will become easier, you will be able to burn more calories and if you want body fat loss, it is another way to assist you.

Hydration test

Weigh yourself pre and post your training session. It is unlikely that you will burn off 1-2kg of fat in a training session; it will be fluid and electrolyte stores. If you want to take it to the next level, if you know roughly what your sweat rate is, then you will be able to know what you need to drink during training to prevent any dehydration. Below I have showed an example of determining dehydration level and sweat rate:

Pre –exercise weight: 65kgs
Post – exercise weight 63kgs
Volume of fluid consumed during the session (1L) – urine losses (~500mL)
Exercise Duration: 2 hours

 Calculations:
Total Body weight percentage loss: 2/65kgs X 100 = 3.07% – signifies dehydration
Fluid Deficit (L): 65-63kgs = 2kgs
Sweat losses: 2kgs + 1kg – 500mL = 2.5kgs
Sweat Rate (L/Hr) = 2.5kgs/2hours = 1.25L/Hr

So for this persons sweat rate, they should be consuming 1.25L of water each hour of training to prevent dehydration and ensure it is not adversely affecting their performance.

Test it out, see if it makes a difference to your training. One other tip I will quickly give this week is to also try and replace 150% of your losses over 4-6 hours after training if possible. I find this will also make a big difference on recovery! So if you have lost 1kg, consume at least 1.5L of water over 4 hours.

Happy drinking 🙂


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