Sports Drinks – they’re everywhere now. But are they worth it?
The short answer: Depending on when, why, and how you’re using them – Yes.
When would sports drinks have NO benefit?
If sports drinks are drunk during the day (not while exercising), they only add extra sugar and calories that your body simply doesn’t need. It’s best to stick with water during these times.
Also, if you’re working out less than 45 minutes, water is sufficient for good hydration. In fact, studies show that when exercising less than 30 minutes, extra fluid (water or otherwise) has no benefits to performance.
When are sports drinks needed?
If you exercise for under 90 minutes and the temperature is under 80F, water is usually just fine. However, if it is hot out or if you will be training for longer than 90 minutes, a sports drink that combines carbohydrates with electrolytes is your best bet for optimal performance.
Why is hydration important during exercise?
During exercise, the body generates up to 15 times more heat (energy) than at rest – and the only way to release the heat is through sweating.
If you don’t have enough fluid in your system to help eliminate this excess energy, your body can overheat quickly, resulting in poor performance, dehydration, weakness, and dizziness.
So when it’s hot out, or you’re a heavy sweater, you may dehydrate faster. Even just 2% dehydration can decrease your performance.
Interestingly, once dehydrated the body absorbs fluids slower, making it even harder to catch back up!
The Science Behind Sports Drinks
Carbohydrates
In most sports, the point of fatigue is closely linked to glycogen depletion in the exercising muscle.
Taking in a steady flow of carbohydrates (specifically the simplest form of carbohydrates: sugar) during exercise can help increase your performance. Studies show that fueling can help you maintain a faster pace for longer, reduce your perception of fatigue, and help improve your cognitive function and focus during a race.
Bonus: Carbohydrates stimulate sodium absorption in the intestines, which together then bring water with them as a result of osmotic drag. This means carbohydrates (sugar) are an integral part of helping maintain blood volume by encouraging the body to retain the fluids you drink. This keeps you hydrated for longer.
While sodium does help pull water into the body from the intestines as well, the effect is much smaller than that of carbohydrates. Sodium is more important in the retention of water.
Multiple types of sugars are the key to a happy gut
The body absorbs each type of sugar via a different pathway. If we take in too much of one type of sugar, we overwhelm that pathway and this can lead to gastrointestinal distress.
Having multiple types of sugars, both long and short-chain, can help you absorb a much higher amount of carbohydrates.
Glucose is the most important and easiest to absorb, so this should be the primary sugar in your sports drink. Fructose is next. It takes a bit longer to be absorbed, so this should make up a smaller percentage of the drink. Maltodextrin is used as a longer-chain carbohydrate.
Sports Drink Osmolality
Osmolality measures the concentration of particles that are dissolved in a fluid. This is an important factor for sports drinks because it highly influences how well you can absorb the sports drink. For sports drinks, the amount of carbohydrates and electrolytes will affect osmolality.
There are two main types of osmolality in sports drinks: Hypotonic, isotonic, and hypertonic.
Isotonic Solution
An isotonic solution has the amount of particles in the fluid as the osmolality of our blood. Some people think this makes it a preferable hydration drink, though studies aren't firm on this.
Isotonic solutions are usually between 280 - 300 mOsm/Kg. This puts a sports drink at about 6-8% carbohydrates.
Best for: Short duration, high intensity.
Hypertonic Solution
A hypertonic sports drink is dense, it has a lot of particles. It's more difficult to absorb since the body has to pull in more water to make it isotonic before it can be absorbed well. This creates a fluid shift from your body to your gut, delaying gastric emptying and hydration.
Unfortunately, this usually ends in digestive issues when the body is dealing with the stress of a race or workout.
Anything more than 300mosm/Kg can cause issues during exercise or races.
Best for: Recovery.
Hypotonic Solution
Hypotonic sports drinks have fewer particles in the same amount of fluid. Counter to previous thought, studies show that this type of sports drink works best for hydration during exercise.
Turns out that at higher metabolic rates (exercise), these low osmotic pressure drinks work best to help keep you hydrated.
Most sports drinks are hypotonic, staying between 200-250mosm/Kg.
Best for: Endurance training and races.
Bottom line
Both Isotonic and Hypotonic work well for your needs as an athlete, but stay away from hypertonic sports drinks as a general rule.
Electrolytes
Along with water, sodium is also lost in sweat. This is the most important electrolyte when it comes to exercise.
Sodium
Sodium, the most abundant cation, and chloride, the most abundant anion help with muscle contractions and nerve signaling (Salt is made up of NaCl, or Sodium Chloride). Without enough sodium, hyponatremia (low sodium) sets in. Symptoms include nausea, disorientation, slurred speech, and confusion.
Hydrating with water alone in a hot environment dilutes the sodium in your bloodstream even further, causing potential health issues. Not good for performance!
In fact, drinking water alone can dehydrate you during extreme heat or long-duration competitions/training. Without sodium, water is simply expelled by the body via urine and sweat.
How much sodium do you need?
Most sports drinks contain about 30-90 mmol/L of sodium – an optimal amount to replenish normal sodium loss.
If you’re a salty sweater (you can tell by how much salt is dried on your skin and clothes after a workout), you may even need additional salt tablets in a long-distance race in addition to a sports drink.
Talk to your coach and registered dietitian nutritionist to see if this is an appropriate option for you.
What about soda or soft drinks?
Soft drinks contain virtually no sodium (1-2mmol/L), so while they may be tempting to drink during a long race, note that they will not be contributing to your electrolyte needs.
What about Coconut water?
As you may have read in this article, coconut water is not the best sports drink for intense workouts lasting longer than 75 minutes. It simply does not have enough sodium to keep you well-hydrated and performing your best.
Your Fluid Needs per Hour
The goal of hydration is to maintain body weight. On average, an athlete needs about 8-12 ounces of fluid every 15 minutes of exercise to maintain top performance and hydration.
Remember that even slight dehydration makes it difficult for your body to absorb fluids and rehydrate, so make sure you are well-hydrated going into training or competition. Check your pee! It should be light yellow.
Drinking 8 ounces of fluids about 20 minutes before the race can also prime the intestines to absorb more fluids during the race.
Note that these are rough estimates. To understand your individual fluid needs, a race fueling plan that involves a sweat test will help you fuel optimally.
Figure Out How Much Fluid You Need:
Daily Fluid Needs: 30ml/kg
(Your weight in pounds) / 2.2 = Kg body weight
Kg x 30 = Total ml fluid needed per day
(Total ml) / 240 = Number of cups you need to drink per day
Exercise Needs: (Added to your daily needs)
Drink 2 cups (16 oz) 2 hours before exercise
Drink 8 oz 10 minutes before exercise
Drink 8 oz every 15-20 minutes during exercise
* Weigh yourself before and after training/competition and for every pound you lose, drink 16 ounces (2 cups) of fluids.
Make Your Own Sports Drink
Don’t want to spend money on commercial drinks? You can make your own sports drinks with the right amount of sodium and carbohydrates to fuel your workout.
Homemade Sports Drink Recipes
Dextrose, Maltodextrin, and Juice-based
3 Tbsp Dextrose Powder
1 Tbsp Maltodextrin Powder
1/2 cup apple or grape juice
1/4 tsp salt
20 oz water
Per 8 oz Serving: 72 calories, 18g carbohydrates, 190mg sodium
~ Rachel Gargano, RD
Honey and Juice-based
3.5 cups water
1/2 cup orange juice (not concentrate)
2.5 Tbsp honey
1/4 tsp salt
Per 8oz serving: 50 calories, 14g carbohydrates, 143mg sodium
~ Dawn Jackson Blatner, RD
Sugar and Juice-based
1/4 cup sugar
1/4 tsp salt
1/4 cup hot water
1/4 cup orange juice (not concentrate)
1 Tbsp lemon juice
3.5 cups cold water
Dissolve salt and sugar in hot water. Add orange juice, lemon juice, and cold water. Stir.
8oz: 50 calories, 12g carbohydrates, 143mg sodium
~Nancy Clark, RD
Sources
Orrù S, Imperlini E, Nigro E, et al. Role of Functional Beverages on Sport Performance and Recovery. Nutrients. 2018;10(10):1470. Published 2018 Oct 10. doi:10.3390/nu10101470
Mata F, Valenzuela PL, Gimenez J, et al. Carbohydrate Availability and Physical Performance: Physiological Overview and Practical Recommendations. Nutrients. 2019;11(5):1084. Published 2019 May 16. doi:10.3390/nu11051084
Rowlands, D.S., Kopetschny, B.H. & Badenhorst, C.E. The Hydrating Effects of Hypertonic, Isotonic and Hypotonic Sports Drinks and Waters on Central Hydration During Continuous Exercise: A Systematic Meta-Analysis and Perspective. Sports Med 52, 349–375 (2022). https://doi.org/10.1007/s40279-021-01558-y
Institute of Medicine (US) Committee on Military Nutrition Research; Marriott BM, editor. Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations. Washington (DC): National Academies Press (US); 1993. 3, Physiological Responses to Exercise in the Heat. Available from: https://www.ncbi.nlm.nih.gov/books/NBK236240/
Institute of Medicine (US) Food and Nutrition Board. Committee on Military Nutrition Research: Activity Report. Washington (DC): National Academies Press (US); 1994. Use of Carbohydrate-Electrolyte Solutions for Fluid Replacement. Available from: https://www.ncbi.nlm.nih.gov/books/NBK231364/
Rowlands DS, Kopetschny BH, Badenhorst CE. The Hydrating Effects of Hypertonic, Isotonic and Hypotonic Sports Drinks and Waters on Central Hydration During Continuous Exercise: A Systematic Meta-Analysis and Perspective. Sports Med. 2022;52(2):349-375. doi:10.1007/s40279-021-01558-y
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