Considering Hydration Status

Why is Hydration important?

Hydration is important for cardiovascular function, body temperature regulation and cognitive and physical performance

It is important for transport of oxygen and nutrients to the brain and exercising muscles

When individuals exercise, heat is created within the body – evaporation of sweat from the skin surface is the primary mechanism by which the body cools itself. Sweating is important to prevent dangerous increases in body core temperature.

Individuals should prevent significant dehydration. This can be defined as a greater than 2% loss of body weight, because it is associated with impaired performance.

Should I measure Hydration Status?

Individual sweat rate can be determined by genetics, environmental and exercise conditions. Sweat rates can vary quite significantly as noted per position stand by Barnes et al., 0.3L-2.4L/hr.

Gender specific ranges can fluctuate as much as 0.4-1.3L/hr for females and 0.6-1.8L/hr for males.

 In order to estimate sweat rate in L/hour, add weight lost and fluid consumed during exercise, divided by the duration.

Sweat rates are variable and athletes should measure their individual sweat rate by:

1.     Measuring their body weight on a scale whilst wearing as minimal clothing as possible

2.     Measure their water bottle on a scale before commencing the exercise session

3.     Perform usual workload/intensity for a training/competition block lasting 60 minutes

4.     Return to the scales wearing the same amount of clothing as the pre-exercise weighing (Documenting any food consumed during the workload)

5.     Reweigh water bottle to note the intake of fluid during exercise. Do NOT forget to include whether or not you needed more water bottles during the exercise bout

6.     Calculate the amount of fluid loss between pre and post exercise INCLUDING the amount of fluid that was indulged

For example: Pre session weight – Post session weight + Difference in fluid intake.

Eg: 90kgs – 89kgs + 300ml/g of fluid drank = 700g fluid loss/hr

Try to calculate your own sweat rate during your next exercise session and record your result! This is especially important if you are seeking a fluid strategy plan with your accredited Sports Dietitian.

Blog post by,

Nicholas Berlin

4BND

IOC Dip. Sports Nutrition.