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Runners in the New York City Marathon pass a refreshment station in the Harlem neighbourhood of New York on Sunday. Wilson Kipsang and Mary Keitany, both of Kenya, took first place in the men’s and women’s divisions of the race.ANDREW WHITE/The New York Times

Commercials for sports drinks show neon sweat pouring from chiselled athletes pushing themselves to the limit. These ads suggest that the athletes are losing the very nutrients that sports drinks provide, which raises the question: Are sports drinks necessary? Do these drinks really help boost athletic performance? And what about the recreational athletes among us who are looking to hydrate during or after a workout – is water or a sports drink best?

Let's take a closer look at what you're losing when you sweat. Sweating is your body's natural way of cooling you down, but it also causes losses of water and electrolytes, such as sodium, potassium and other minerals.

For some people, replacing electrolytes lost from exercise is essential to preventing dehydration, which can lead to poor performance, may cause muscle cramps and can increase the risk of heat stroke.

Sports drinks are helpful for people who exercise intensely and/or for periods longer than one hour. They can also be beneficial for those who exercise in hot or humid weather and/or wear protective equipment that prevents sweat from evaporating (examples include football and hockey uniforms). And you may want to reach for one if you sweat lots or have very salty sweat (you can tell if you have salty sweat if you find your face is gritty with salt after a workout or you can see white salt powder on your hat or clothes after a workout).

So if you're going for a run for 30 minutes on a cool, fall evening, is a sports drink required? No. And a sports drink is not a good choice as a beverage, unrelated to exercising. This will add unnecessary sugar to your diet.

Drinking water when you're thirsty will sufficiently replace fluids in this case.

If you feel hungry after exercise, have a snack with some carbohydrate (fruit, bread, grains or yogurt) and moderate amounts of protein (yogurt, cheese, nut butters, lean meats or legumes).

For those who can benefit from sports drinks, here's a breakdown of what goes into them.


Why you need it: To replace the fluids lost through sweat to prevent dehydration.

Amount you need: There is no "one size fits all" rule, because each athlete will have different needs. As a starting point,  most athletes need 400 to 800 mL (about 11/2 to 3 cups) or more of fluid for every hour of activity. The amount will vary based on your size, the type of activity you are doing, your fitness level and the temperature and humidity in which you are exercising.

Pay attention to thirst: Feeling thirsty could mean you are already dehydrated. The colour of your urine could be another key. Pale yellow or straw-coloured urine means you're probably getting enough fluids. If your urine is dark yellow or amber-coloured, this means you need to drink more fluids.

To get a rough idea of how much fluid you need to replace, weigh yourself before and after exercise. Any weight loss is likely sweat loss and reflects how much water you need to replace over the day with your regular food and beverages. For each kilogram of weight lost, you can assume you lost approximately one litre (four cups) of water.

Sodium and potassium

Why you need them: Your body needs sodium and potassium to keep fluids in balance and for your nerves to send signals to your muscles, including the heart.

Sodium in sports drinks also helps you hydrate because some research shows it causes people to drink more and urinate less. It might also help to prevent muscle cramps in some people. Athletes lose less potassium than sodium in the sweat.

Amounts you need: Look for a sports drink that has at least 460 milligrams of sodium per litre. If you tend to experience muscle cramps or are an ultra-endurance athlete, meet with a sports dietitian for individual counselling on the right amount for you.

Choose a sports drink that contains approximately 78-195 milligrams of potassium per litre.

Carbohydrates (sugar)

Why you need it: Sugar provides energy to working muscles and the brain and helps maintain your blood-sugar levels during exercise, which helps you work out harder and longer.

Amount you need: Having 30-60 grams of carbohydrate per hour of exercise can improve performance in high intensity, short spurts of activity and endurance sports by increasing power and helping delay time to fatigue. The type of carbohydrate also matters: Including different sources such as glucose, fructose, sucrose and maltodextrin can help with absorption. Most sports drinks contain a mixture of carbohydrate sources.

Having more than 80 grams of carbohydrate per litre during exercise can lead to stomach cramps and negatively affect performance. Pop, juice and energy drinks fall into this category so they aren't helpful during exercise. Also avoid carbonated drinks during exercise – feeling bloated or full will distract you from performing at your best and make it harder to drink enough during exercise.

Shouldn't I avoid extra sugar?

Are you concerned about the sugar that sports drinks will add to your diet? Think about it the same way you would think about adding salt to your diet – not ideal for the average person. But many athletes have higher needs for energy and for salt, so if you do need sports drinks, the sugar and salt they provide can fit into a healthy diet.

If you're looking to cut down on added sugars, avoid drinking juice and pop, read food labels and cook at home more often.

Health Advisor contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging.

Christy Brissette is a registered dietitian and national spokesperson for Dietitians of Canada. She is passionate about food and providing clients with the knowledge and skills they need to make healthier meals at home. Christy co-hosts The ELLICSR Kitchen, an interactive cooking and nutrition show for cancer survivors at the Princess Margaret Hospital. You can follow her on Twitter @80twentyrule or visit her website

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