sduncan

Working out is great for your body, mind, and lowering stress. However, many of us make the mistake of not drinking enough water while exercising. Not only can dehydration lead to muscle cramps and serious heat illness, but it can also hurt athletic performance.

Being hydrated means that our bodies have enough water to function properly. Each day, we drink fluid, but also lose body water from sweat, urine, and from exhaling. When the balance is tipped between what we drink and the fluid we lose, our bodies can become dehydrated.

When does dehydration start to hurt your workouts? If you are doing intense aerobic exercise like running, your heart and lungs are working hard, and your body loses fluid. Losing more than 2% of your body mass through water during exercise can lower your athletic performance. What does this look like? Let’s say you weigh 160 lbs. If you are less than 157 lbs right after an intense 2 hour run, then you have lost about 2% of your body weight. This quick weight loss is not fat…it is likely because of water loss through your sweat and breath. However, because you have lost 2% of your body weight in water, your heart needs to work even harder to pump the body with blood, which transports the oxygen and nutrients that you need. If you go to work out again without replenishing your body water, you are going to feel tired, and the exercise you are doing is going to feel harder than it should. Staying hydrated by drinking enough fluid helps your body to work properly, and feel more energetic: perfect ingredients for better workouts.

How much water should you drink?
How much does your body need you to drink while working out? The answer is that it all depends! The intensity, length of exercise, weather, clothing, and your body’s metabolic rate all play a role in how much fluid you need.

Some signs that you are drinking enough water are that you don’t feel thirsty often, and that your urine is colourless or light yellow. If it is dark, or of less volume than about 1.5 litres, you might be dehydrated.

Here are some general guidelines for hydrating before, during and after exercise.

Before

• Drink about 2 cups (500 mL) of water, 4 hours or more before working out.
• Drink about a cup (250 mL) of water, 10-15 minutes before exercise.

During

• For every 10-15 minutes while exercising, drink between 1/3 to 1 cup (80-250 mL) of water if you are exercising for an hour or less.
• Once you have passed 60 minutes of working out, its time to pull out a sports drink. For every 10-15 minutes after this point, drink 1/3 to 1 cup (80-250 mL) of sports beverage that has electrolytes and carbohydrate.

After

• If you weigh less after your workout, chances are your body has lost a lot of water. Drink 2.5-3 cups of water for every 1 pound lost, within 2 hours after working out.

Remember, what you are drinking matters! Not all beverages are created as equals. Surprisingly, some drinks actually dehydrate your body: alcohol and highly caffeinated drinks. While alcohol and caffeine can be fine in moderation, focus on drinking water throughout the day.

For more information on what to drink during exercise, check out this resource from the American College of Sports Medicine: https://www.acsm.org/docs/brochures/selecting-and-effectively-using-hydration-for-fitness.pdf

Cheers, to better workouts!

By Lauren Kennedy, BASc, MScFN Candidate

References

Kenefick, R.W & Cheuvront, S.N. (2012). Hydration for Recreational Sport and Physical Activity. Nutrition Reviews. Retrieved from: http://onlinelibrary.wiley.com.proxy1.lib.uwo.ca/doi/10.1111/j.1753-4887.2012.00523.x/epdf