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Sport Nutrition 101 - making a case for sport drinks

If you are a long distance athlete, you've likely experiences several pronounced and uncomfortable symptoms related to unsuccessful fueling/hydration methods. Headache, dehydration, swelling, bloating, sleepiness, lethargy, lack of appetite, nausea, chills, fatigue, deep muscle aches, moodiness and dizziness are not just performance limiting but they are also extremely risky for your overall health. 

Proper fueling during intense or long duration exercise can help you sustain a desirable effort to maximize training adaptations. 
Proper fueling/hydration also minimizes the stress load to help keep your body in better health.
Proper fueling/hydration in training also helps you practice fueling strategies for competition as you can train the gut to tolerate nutrition while exercise at various intensities.

Contrary to the opinion of other nutrition experts, I'm a huge proponent of prioritizing sport drinks during training. I've also had great success prioritizing liquid calories during long distance training (for myself and for the hundreds of athletes that have consulted with me on sport nutrition).

If you are training for a long-distance event (90+ minutes) or training intensely in the heat for 60+ minutes, a sport drink provides a practical and easy way to obtain fluids, electrolytes and carbohydrates, in the right formulation to optimize digestion and absorption. Because you will always need to consume fluid when you train in the heat, a sport drink makes the most sense as the most practical, convenient and easy-to-replicate source to meet your fluid, sodium and carbohydrate needs.
Most sport drinks are very safe and effective but are often misused or neglected – especially in the heat.

Let's learn a bit more about sport drinks and clear up any confusion around sport nutrition products. 

Sport Drink Formulation
For a sports drink to work effectively, it must have the same or less than osmolality of blood. As a reference, blood plasma has an osmolality of 280-300 milliosmoles per kilogram and a bottle of Gatorade has an osmolality of ~330 mOsm/kg. A sports drinks osmolality (Iso-, hyper- or hypotonic) is dependent on the carbohydrate type (ex. glucose, fructose, maltodextrin) and concentration (grams) in a solution (fluid ounces) – in other words, how quickly it can absorb into your blood stream. If a drink’s osmolality is greater than the blood’s (concentrated or hypertonic), liquid will be pulled from the blood and into the intestine to equalize the two concentrations – this net movement of water is theoretically dehydrating. A iso- or hypotonic drink, in contrast, will provide a favorable osmotic gradient so that water diffuses into the cells. If you fail to replace the fluids and electrolytes (sodium) lost in sweat, a cascade of negative events occurs, such as a rise in osmolality, a drop in blood pressure and an increase in heart rate. In contrast, if you drink too much water too quickly and don’t consume drinks with adequate sodium, sodium levels will drop as body water levels rise, causing cells to swell. The tonicity of your sport nutrition is extremely important and likely the main contributor to GI issues, dehydration and early fatigue/bonking. The liquid component is very important and why so many athletes experience issues with only consuming solid food, gels and chews (especially when running). 
-Hypotonic - lower concentration of fluid, sugars and salt than the blood. Fast absorption into the bloodstream for quick hydration and electrolyte release. Ideal when you need to hydrate quickly and are not trying to maximize carbohydrate consumption (example during high intensity running, running off the bike and post workout).
-Isotonic - similar concentration of fluids, sugars and salt to blood. When your focus is more on carbohydrate delivery than on hydration/sodium. Because the energy and electrolyte release is slower, a isotonic beverage requires more time to get across the gut wall. This is ideal for long bike rides. An isotonic beverage would work well for a high intensity and/or moderate length bike workout, a swim session and low intensity longer runs. 
-Hypertonic - higher concentration of fluids, sugars and salt to blood. Because of the slow absorption rate, it's not advised to rely solely on chews/gels/bars during your workout. Concentrating your drinks (ex. multi-hour bottle of sport nutrition) is a culprit of Gi issues, nausea and feeling extra thirsty as your body has to move water from the bloodstream to the intestines to dilute fluids before absorbing them. A hypertonic beverage is ideal post workout when you are trying to maximize carbohydrate intake. 

What about Juice, Coconut Water or making my own sport drink?
Because fructose uses a different intestinal transporter compared to glucose and once in the bloodstream, has to be taken up by the liver to be processed into a usable fuel source for the muscles (which can take up to 90 minutes), juices are not recommended as a "sport drink" during exercise.

Although coconut water contains calcium, phosphorus and magnesium (electrolytes found in sweat), sodium and chloride are the major electrolytes because they reside in the extracellular fluid. Compared to a sugar-rich hydration beverage, coconut water is a safe and natural option to occassionally enjoy as an alternative to water. However, to sustain moderate to high-intensity exercise for longer than 90-minutes, the body depends on ingested carbohydrates and sodium – both of which lack in appropriate amounts in coconut water. Additionally, if you are paying extra for coconut water to increase your daily potassium intake, look no further than the produce aisle – a large potato contains 1553 mg of potassium! If you enjoy the taste of coconut water over plain water, choose it for light activity. But to prevent dehydration, replace lost electrolytes and provide the muscles with carbohydrates, a well-formulated sport drink is encouraged. In all other situations, plain water should be your go-to hydration beverage.

As for making your own sport drink - leave it to sport nutrition companies. Instead, make your breakfast, lunch and dinner as you can get more bang from your buck by preparing your meals instead of being a chemist in your kitchen. 

Gels, Bars and Chews
Gels, bars and chews are highly concentrated, portable sources of carbohydrates that are easy to consume during exercise but they lack the fluid and electrolytes that you’d find in a sport drink and are not in the right formulation by themselves to be easily digested and absorbed. Same goes for salt pills. Most gels and chews contain around 100 calories (or 25g of carbs) per serving. More concentrated in carbohydrates compared to a sport drink, gels and chews must be consumed with water to encourage gastric emptying. For every 25g of carbohydrates, at least 12-16 ounce of water should be consumed. Athletes may prefer to dilute a gel into a flask or bottle of water to create a more dilute concentration. Considerably low in sodium (50-100mg), gels and chews are ineffective to replenish sodium lost in sweat. Remember, your fluid, sodium and carb intake will be for nothing if it’s just sloshing around in your gut. As a refresher, scroll back up to re-read about the tonicity of a sport drink and how complicated fueling/hydration becomes when you try to meet your sodium, fluid and carbohydrate needs with different sources. 

This doesn’t mean that you can't consume solid food or a gel or chews during long distance training, but to minimize GI issues and to simplify sport nutrition, I strongly advise to prioritize liquid sport drinks when you train (and race) and use chews/swig of gel for a central nervous system pick-me-up and bars/solid food to keep the tummy happy.

Digestion and Absorption

When applying the topic of sport nutrition, it's important to understand that just because you are consuming carbohydrates, sodium and water, this doesn't mean that your muscles are receiving what you are consuming. If a product is not consumed properly (or formulated properly when mixed), it'll simply hang around in the gut - causing bloating, a sloshy stomach, heart burn, belching, vomiting, gas and/or diarrhea. fluid ingestion. This can further lead to dehydration and glycogen depletion.

Water is absorbed in the small intestines and by the time it enters the large intestines, roughly 80% absorption has occurred. The rate of gastric emptying and intestinal absorption are dependent on the volume and formulation of the beverage. The greater the concentration, the greater the osmolality. This is why you should never concentrate your sport drink – like putting 400-600 calories (2 or 3 hours worth of calories) in one bottle that only has 28 ounces of fluid. When you drink water, there’s a drive for the water to dilute the blood (water moves toward blood) but if you drink a more concentrated beverage than blood, like a hypertonic sport drink or soda or juice, water will move from inside the bloodstream and into the gut – which is dehydrating. The inclusion of electrolytes and glucose in a beverage promotes retention of fluids. When you add a little sugar with sodium (as in a sport drink), you can pull a great amount of water across the small intestines, optimizing water absorption. To help with fluid and electrolyte loss, it's not just about the carbs. You also need to ingest water and electrolytes from a sport drink to keep plasma volume at normal levels. 

There's also an added benefit of a sport drink having multiple carbohydrates for better digestion and absorption but I'll save that for another blog. 

With all this in mind, there are several reputable sport nutrition companies out there to help meet your needs. Here are a few of my favorite sport drinks: 

Swim and Run: 
-Clif hydration
-NBS Carbo-hydration
-Nuun endurnace 
(Don't forget to wear a hydration pack/belt to make it easy to fuel/hydrate when you run. My go-to is Naked)

-Infinit (no protein/fat added)
-Maurten 320
-Skratch superfuel 

What else should you look for in a sport drink? 
  • Simple ingredients - carbohydrate, sodium, natural flavors, preservative (ex. citric acid). 
  • Taste - vary the flavors of your sport drink. If you don't like the flavor or texture, you probably won't drink enough of it. If you love it and consume it too often/frequently, you may experience taste bud fatigue and dread it on race day. Consider refreshing and light-tasting flavors especially for the later half of longer workouts. 
  • Texture - A sport drink should feel hydrating. If it leaves a funny taste in your mouth or if it's difficult to consume, it's not the right drink for you. 
  • Avoid caffeine, protein, fat and other "boosters" in your drink. If you need a boost, get it from an outside source so that you aren't stuck with those added products in your drink (as many times they can cause GI distress). 
  • Reach out to a sport dietitian for help. Finding and utilizing sport nutrition is a science and involves a bit of trial and error. Take away the guessing and reach out for help.