PRE-SEASON TRAINING HYDRATION

VIGILANCE IS THE KEY TO MAINTAINING WATER BALANCE DURING PRE-SEASON TRAINING

is contributed to the body from metabolism (~300 mls) and the rest must be consumed in food and liquids (~2.5 L) to achieve water balance and avoid the effects of dehydration (7). In an exercising individual, water losses from breathing due to increased respiration rates and water losses through sweat, increase dramatically in order to dissipate the excess heat created in the body due to physical activity. The body is remarkably inefficient at

metabolic transfer of stored energy into muscular work meaning that about 75% of the energy generated by the burning of carbohydrates, fats and protein for exercise is liberated as heat (8). During exercise several powerful methods of heat loss from the body kick into gear to prevent an excessive rise in core temperature: increased blood flow to the body’s surface; increase sweating to dissipate heat through evaporation; and a decrease in urinary output to conserve water for temperature regulation.

Exercising indoors and in hot environments

and especially hot and humid environments, significantly add to the challenge of dissipating the excess heat generated during exercise and increase the chances of dehydration, serious decreases in performance, and heat-related illness. Heat acclimatisation and optimising hydration status through the consistent and well-timed use of fluid replacement beverages containing modest amounts of sodium and glucose are effective interventions. The former lowers temperature thresholds for vasodilation at the body surface and the onset of sweating. The latter improves water absorption and retention (8).

VIGILANCE IS THE KEY Thirst is often not an adequate indicator. While thirst cues begin when body water loss is about 1% of body weight, most of us are so accustomed to over-riding thirst cues that we only start to notice them when we are well on our way to more deleterious levels of dehydration. However, if you are thirsty, by all means drink to replenish lost fluids. Most athletes during intense training periods and, certainly when exercising indoors or in warm or hot and humid outdoor conditions, need to

www.sportEX.net consciously drink fluids to replenish losses.

START WORKOUTS FULLY HYDRATED It’s important not only to replace the water used and lost during your workouts, but also to consume adequate fluids to replace water used throughout your day for metabolism, expiration, waste removal and perspiration. Average water needs throughout the day for time spent in sedentary or light active pursuits is between 8 and 9 cups for women and between 11 to 13 cups for men. It’s important to fit these fluids in throughout the day so that you start your workouts fully hydrated. The last 2 cups or 16 ounces can be consumed 1 to 2 hours before the workout.

FLUID INTAKE DURING ACTIVITY The amount of fluid needed during activity will vary with the temperature, humidity and the type of activity. A good rule of thumb is to drink about 150 to 300 mls every 10 to 20 minutes – taking care not to drink more than is needed to counter water losses due to the activity (9). When the workout has ended, athletes need to replace water lost at a rate of 2 cups (500 mls) for every pound of weight lost during activity. To this end, it is helpful for athletes in pre-season training to weigh him or herself before and after practice to learn to estimate the amount of additional fluid he or she needs to drink to get back into water balance.

In addition some athletes find it helpful to

slightly hyperhydrate right before activity with plain cold water, diluted fruit juice or a glucose- electrolyte drink. For most athletes it is safe to drink up to 20 ounces of one of these fluids in the last 15 minutes before your workout and if the body’s glycogen stores are low or the workout is extended the carbohydrate in a diluted fruit juice or sports drink may improve exercise endurance. Pre-exercise hyperhydration is not necessary and may not be appropriate for some athletes, but for others it lessens the need for vigilance during exercise.

WHAT SHOULD I DRINK? The best fluid replacement beverage is still plain cool or cold water. During and after exercise, fluid and electrolyte replacement beverages (diluted sports drinks such as Gatorade) are also good choices which can help to replace sodium and other minerals lost in sweat and for bouts of activity over 60 minutes can help to keep blood glucose at healthy levels. Diluted fruit juices or juice drinks may also be used during or after exercise to nearly the same effect. Sweetened beverages, as long as they are not too concentrated, may help some athletes achieve adequate hydration as they are sometimes preferred. Young athletes in particular are more likely to achieve hydration goals if the beverage offered is considered tasty.

Alcohol and caffeine containing beverages

may be enjoyed in moderation by adult athletes for various other reasons but should

HYDRATION KEY FACTS n Water loss of 3-4% of body weight can affect performance equaling a: 2% loss of strength 3% loss of power

10% drop in short high intensity activity levels 2% loss affects skill levels.

n At rest adults lose 2-3 litres a day via sweat, waste products and breathing. n To replace, men need 11-13 cups of water per day, women 8-9 cup (cup = 250mls). n During exercise drink: 150-300mls every 20 minutes 500mls for every 1lb weight loss during exercise

n Adults approx 1.5 litres urine per day. n Water loss of 1% of body weight occurs before you feel thirsty.

13