Hydration for Runners

A good hydration strategy is an essential part of every runner's preparation for training and events.

Commercial sports drinks have been developed on sound scientific principles, and runners can turn this science into optimal performance and well-being by learning the practical aspects of what to consume during their event.

They also need to look at the timing of consumption and the amounts needed for optimum performance. Just as general training and competition strategies should be tailored for individual runners in accordance with their unique needs and preferences, so should their drinking and eating choices before and during exercise.

It is important for runners to identify their own winning formula, and to know how to manipulate this in hot or cold environments.

Key principles:

• Limit dehydration during training and events by drinking water or a sports drink;
• Get a feel for sweat rates during exercise so that drink practices can be adjusted accordingly. It is not necessary to drink enough to prevent loss of body weight, but the amount of dehydration should be normally limited to a loss of less than 2% of body weight (i.e., 1kg for 50kg person, 1.5kg for a 75kg person, and 2kg for a 100kg person);
• Since the negative effects of dehydration on high intensity performance are greater in warm environments, upgrade drinking practices in these conditions to minimise the overall fluid deficit. This may mean drinking before and during longer runs;
• Don't drink at rates that are greater than sweat losses so that you actually gain weight.

When do you need more than Water?

The provision of additional fuel to the muscle or brain can be of benefit to any event lasting longer than about one hour, which would otherwise result in fatigue. The intake of carbohydrate that is generally associated with performance benefits is from 20-60g per hour.

The use of sports drinks with a carbohydrate content of about 4-8% (4-8 g/100 ml) allows carbohydrate and fluid needs to be met simultaneously in most events.

Intake of a carbohydrate-containing drink may provide performance benefits for distance running.

Consuming a carbohydrate-containing drink (or light foods) may help to maintain skills and judgment when middle and long distance runners become fatigued.

Sodium should probably be included in fluids consumed during training sessions or events lasting longer than one to two hours.

Caffeine is present in many commonly available beverages and foods, and can enhance both physical and mental performance. This benefit can be obtained with the relatively small doses of caffeine that are commonly consumed by people of various cultures (e.g. about 1.5mg/kg of body weight, as found in a small cup of brewed coffee or 500-750ml of a cola beverage).

How to estimate Sweating Rate

Measure body weight both before and after at least one hour of strenuous exercise. These readings should be made with the runner wearing minimal clothing and while bare footed. The post-exercise reading should be taken as soon as is practical after the session, and after toweling dry.

Note the volume of fluid consumed during exercise (litres).

Calculations:

Sweat loss (litres) = Body weight before exercise (kg) – Body weight after exercise (kg) + fluid consumed during exercise (litres)

To convert to a sweat rate per hour, divide by the exercise time in minutes and multiply by 60.

Note: 2.2 pounds equals 1kg and converts to a volume of 1litre or 1,000ml or 34 ounces of water.

Rehydration after Exercise

Recovery after exercise is part of the preparation for the next exercise session, and replacement of sweat losses is an essential part of this process. Both water and salts lost in sweat must be replaced.

Aim to drink about 1.2-1.5litres of fluid for each kg of weight lost in training or during an event.

Drinks should contain sodium (the main salt lost in sweat) if no food is eaten at this time. Sports drinks that contain electrolytes are helpful, but many foods can also supply the salt that is needed. A little extra salt may be added to meals when sweat losses are high, but salt tablets should be used with caution.

Try out new plans for fluid and fuel replacement during training – never introduce a new regime during an event.

 

 

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