Runners, cyclists, and triathletes commonly use energy gels. After all, they provide a convenient and ideally dosed energy source, which can be taken in on the fly. Most of these products contain a blend of fast acting carbohydrates (like maltodextrin or dextrose) and slower digesting carbs (like fructose)— they also can contain caffeine. Although energy gels are marketed toward endurance athletes as a convenient food source, recent research published in the European Journal of Sport Science illustrates that these supplements also produce performance-enhancing effects during all out intermittent sprinting exercise. Specifically, athletic participants who ingested a 70ml gel containing 25g of carbs and 100mg of caffeine 1hr before, immediately before, and during intermittent sprint training had decreased fatigue and perceived exertion toward the end of exercise compared to placebo. It should be noted that such effects were likely due to the caffeine content of the gel.
These findings can be extended to those using HIIT to improve performance (not for weight loss) or in athletes who are undergoing repeated sprint training over long periods. Find a gel with caffeine and take one dose 1 hour prior to training, another immediately before you start training, and another 30-60 minutes into the training session. If you are looking to get similar effects without the carbohydrates, take 200-300 mg of caffeine prior to your training session.