Why and How to Stay Hydrated during Workout

More than half of the human body is constituted by water. Keeping your body well hydrated is very essential as it can loose up to  0.4-0.6 L/h water while you are engaged in athletic activity. Thus, the key to start working out is to stay well hydrated not only before, but during and after physical activity too.

Why it is important to stay Hydrated? 

• Water makes up the main component of the human body which ranges between 50 to 60% of body mass in an average adult. Some important functions of water in a human body; transport metabolic end products out of our body, to regulate body temperature and to help in digestion, absorption and transportation of nutrient.
• Our body needs a constant source of fuel as energy. While we workout, body requirement for fuel is further enhanced. Our body uses various fuels (carbohydrate, fat, and protein) to provide energy for this. The breakdown of these fuel increases the heat inside the body and raises the core temperature which needs to be brought down. Our body tries to maintain body temperature by two mechanisms: increasing skin blood flow and sweat secretion. Although necessary, this crucial process also results in a loss of body water and electrolytes from the body.
• Sweat rate is proportional to the metabolic rate. In simpler words, when you work out more, you sweat more and can amount to 3 to 4 litres per hour or as much as 10 litres per day.
• Adequate hydration not only essential for physical stamina and performance. An exercise weight loss greater than 2%, could impair performance.
• In sports where constant concentration is required, cognitive performance of athletes can be impaired if the body is not rehydrated properly.
• Dehydration reduces water inside the body and to compensate this heart rate increases accompanied by a decrease in blood supply to the skin which reduces perspiration and sweating, body temperature rises., reducing physical performance.
• Reduced endurance, increased fatigue,  reduced motivation and prevent injuries associated with dehydration and sweat loss.
• Dehydration of greater than 2% loss
  of body weight increases the risk of nausea, vomiting, diarrhoea and other gastrointestinal problems during exercise.

How much do I need to drink?

Fluid replacement depends upon on an individual needs, environmental conditions, exercise intensity and duration, pre-post body weight and body size.

Though recommended fluid intake while you work out very slightly, in general, it is suggested an athlete should consume 5-7 mL/kg body mass (BM) of fluids 4 h before exercise and an additional 3-5 mL/kg BM 2 h before exercise.

Also, athletes should avoid limiting body mass losses during exercise to no
greater than 1-2% ( 1-1.2 kgs/ 60 kgs) of pre-competition body mass.

Water is an excellent fluid for low intensity and short duration sports. Sports drinks are ideally suited to high intensity and endurance sports.

As per recommendations by American College of Sports Medicine

Before exercise, make sure you are adequately hydrated:

• Beverage consumption with meals will enhance fluid replacement and pre-exercise/event hydration.
• Wait for 8-12 hours or more for recovery of the body after the previous exercise to enhance fluid replacement.
• Tracking daily weight is helpful in evaluating hydration status because postexercise and day-to-day variations are likely from fluid loss.
• Consider drinking 16 to 20 fluid oz 4 hours before exercise, especially if pre-exercise weight is reduced.

2. During exercise

• Drink according to your thirst sensation; no more or no less.
• Drinking more than 800 ml per hour is not recommended and may increase the risk of developing dilutional hyponatremia.
• During extreme weather conditions, fluid intake and pace may require additional adjustment.
• For prolonged exercise, beverages containing 6% to 8% carbohydrate may provide additional benefit.

3. After exercise:

• Drink 16 to 24 oz of fluid for every pound lost.
• Post-exercise meals should include fluid intake.
• Athletes who need to exercise again in less than 12 hours should replace fluid loss by 150% (drink 1.5 L of fluid per kg of weight loss).
• It is recommended the addition of sodium (0,5 to 0,7 g.L^-1 of water) in the rehydration solution in case the exercise lasts more than an hour.
• Consume roughly 30 – 60 grams of
  carbohydrate per hour. 600 – 1200 ml of a sports drink will fulfil this need.