The SiS gel was the first isotonic energy gel on the market, delivering valuable carbohydrates easily and quickly during exercise. With its isotonic formulation, the gel is easy to digest and can be consumed without water, preventing the feeling of fullness that can occur with excessive water intake. Thanks to its convenient format, the carbohydrate gel is easy to carry and quickly available for consumption to help delay fatigue caused by depleted carbohydrate stores. Sport Gel with 100% vegan formulation. This special energy supplier from SIS is also gluten-free. Science in Sport is a pioneer in sports nutrition. Since 1992, we have collaborated with research institutes, elite athletes, and sports scientists.