If you've ever struggled with the application of sport nutrition, you've likely experiences several pronounced, uncomfortable and performance-limiting symptoms related to underfueling, overfueling, dehydration and overhydration such as headache, no urge to urinate, sleepiness, lack of appetite, nausea, bloating, fatigue, muscle aches, moodiness, diarrhea, sloshy stomach, headache and dizziness.
Proper fueling during intense or long duration exercise helps you sustain a desirable effort to maximize training adaptations. You can also practice fueling strategies for competition and train the gut to tolerate nutrition while exercising at various intensities.
Contrary to the opinion of other nutrition experts, I'm a huge proponent of consistently using sport nutrition during training - regardless of the workout intensity and duration. I've also had great success prioritizing liquid calories during long distance training (for myself and for the hundreds of athletes that have reached out to me for sport nutrition consulting).
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. Sport drinks are very safe and effective but are often misused or neglected – especially in the heat.
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.
Because fructose uses a different intestinal transporter compared to glucose or sucrose, 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. Focus on your daily meals and resist the urge to be a scientist when it comes to formulating sport drinks.
As for coconut water, 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 occasionally 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, to replace lost electrolytes and provide the muscles with carbohydrates, a well-formulated sport drink is encouraged.
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 15g of carbohydrates, at least 8-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.
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 for a central nervous system pick-me-up and bars/solid food to keep the tummy happy.
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 OR consuming a sport drink with protein or fat. When you drink plain 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.
As a helpful reminder regarding sport nutrition application, keep things simple, consistent and easy to repeat. Practice, practice, practice.