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FAQ: Measuring hydration status in team sports

When do you make measurements in changes in body weight as an indicator of hydration status?

Players should be weighed on a daily basis, first thing in the morning before eating and after going to the toilet. Ideally, players should be weighed using the same scales, wearing the same amount of clothing and at the same time of the morning. If a player loses more than 1kg from the previous day, further hydration analysis should be conducted. Players, should also be educated around why these measurements and appropriate hydration practice.

If a player loses more than 1kg compared to the previous day, how do you determine weather this is definitely due to dehydration?

The player provides a urine sample for a measure of osmolality, which is one of the most common ways to assess hydration. Although it is not the gold standard measure of hydration status, it is a relatively cheap method and easy to use in the field. Values over 900 indicate dehydration and values under 200 are classed as over-hydrated.

What strategies can be used to rehydrate severely dehydrated players?

Drinking large amounts of water when trying to rehydrate after exercise is not advised. Large volumes of water can cause plasma sodium levels to fall, decreasing feelings of thirst and increasing urine output. Electrolytes should be added to water to help stimulate the thirst response and enhance water absorption. If refuelling is also an issue, carbohydrate can be added to the drink.

Do you need to analyse individual sweat compositions to individualise player’s drinks?

This is an expensive and time-consuming process and is not always available. A simple way to assess players most at risk of excessive electrolyte losses is to look for salty sweat patches on clothing. Wearing a dark cotton t-shirt during exercise that elicits sweat losses and leaving it to dry, is a reasonable indicator of whether a player should be using an electrolyte drink during training and in the first hour after exercise.