In the 60’s and 70’s, carbo-loading was the rage. Athletes consumed a large carbohydrate meal, or better yet, initiated a regimen 7-10 days before a race, in which they loaded up on carbs. The purpose was to fully pack muscle cells with glycogen. This very popular pre-race regimen lost favor when researchers showed that consumption of high-glycemic sugars during a workout or race was just as effective and a lot less complicated. Consumption of high-glycemic carbohydrates like energy gels, raises blood glucose levels which can easily be transported into the muscle and used as energy. Energy gels were an innovation in that they are easily transportable and convenient to use. For energy gels to be used most effectively, they should be consumed with water.
In a similar evolution to sports drinks, the first and still the predominant energy gels contain high-glycemic sugars. Some marketers in hopes of creating market differentiation sell gels that have low-glycemic or longer-acting carbohydrates. In theory, this sounds great. The longer-acting gels provide energy late in the workout. Unfortunately, the marketing hype does not meet the physiological reality.
Long Acting Carbohydrates: Too Little Too Late
During a moderate to high intensity workout, your muscles need energy rapidly. Since longer-acting or low-glycemic sugars require more time to pass from the GI tract to the blood, they are not as readily available. As a result, the muscle cells continue to burn glycogen, depleting their finite stores. The racecar analogy best describes the example. You would not want to put fuel in a racecar that was only available after the race was over.
The addition of protein to energy gels illustrated that even in different forms, protein offers significant benefits in terms of extending endurance and reducing post-exercise muscle damage. In a study comparing the carbohydrate-only gel, GU, to a carb-protein gel, the carb-protein gel increased endurance by 13% and decreased muscle damage by 50%.