The SiS GO Isotonic Gel was the world’s first isotonic gel effectively delivering an easily digestible and quick supply of carbohydrate for energy during exercise. The SiS GO Isotonic Gel was the world’s first isotonic gel effectively delivering an easily digestible and quick supply of carbohydrate for energy during exercise. SiS GO Isotonic Gels are designed to be consumed without water meaning that you can ensure rapid delivery of carbohydrate to your muscles without the feelings of being bloated that can sometimes occur with over-drinking. Buy this Science in Sport GO Isotonic Energy Gel Selection Box (20 x 60ml) Now £13.99.