This will be a double blind cross over study. There will be two treatments involved: Superstarch and glucose (placebo). Participants and investigators will be blinded as an individual not involved in the project will prepare and distribute the treatment (drinks) according to a coding system that is kept confidential until the study is completed. Participants will complete each treatment once and the treatment order will be systematically rotated to avoid any order effect. Healthy men and women soccer players aged 18-35 yr will be recruited. Participants will come to the lab on five different occasions to complete two familiarization sessions, a baseline testing session, and two main trials. During the first visit, the participants will be asked to complete a physical activity readiness questionnaire (as approved previously; Par Q and a participant information form for personal and familial health history to rule out any pathologies or health issues that may preclude them from participating in the present study. Subsequently, the investigators will collect data for VO2max, body composition and sprinting speed. In the second visit, participants will be familiarized with the high intensity intermittent exercise protocol to be used during the study days and will also be allowed to practice the cognitive and skill tests to be used (up to 8 times in order to remove any learning effect that may influence the results). During the third visit, baseline scores for the skill tests will be collected. Participants will perform 4 attempts (the first two will be for re-acclimation) and the last two will be recorded. The remaining two visits will be the study days and will be separated by at least 1 week. The order of treatments will be randomized to avoid any order effect. The night before study day, participants will arrive at the laboratory at 19:00 h and will be fed a standardized meal containing 2g/kg of carbohydrate (pasta and tomato sauce) and will not be allowed any food or drink except water thereafter. On the study day, participants will arrive to the lab at 07:30 h following an overnight 12h fast and will have refrained from exercise, caffeine or alcohol within the prior 24 hours. Baseline capillary blood lactate and blood glucose will be obtained by fingerprick by a trained phlebotomist. In order to ensure the prevention of infection and or contamination during sampling, standard sterile blood handling techniques will be used including the use of new medical examination gloves, alcohol swabs, and disposable sterile lancets. All blood-contaminated materials will be disposed of in a hazardous material labeled disposal (or sharps) container, promptly after analysis. Subsequently, baseline data for the cognitive tests will be collected. After collecting baseline data, the corresponding treatment will be given and 30 minutes after, participants will perform a standardized 10-minute warm-up, followed by the exercise session. The exercise session consists of a 60- minute simulated soccer game divided into 4 x 15-minute blocks exercising (running) at varying intensities that replicate the activity pattern of soccer such as sprinting, jogging, cruising, walking etc. The proportion of time spent at each speed will be allocated based on a time-motion analysis of professional soccer players observed by Reilly and Thomas (1976) as indicated by Clarke et al (2008). During each 15-minute block, cognitive function will be tested using the serial seven subtraction test and the Flanker test. Also, expired gas samples will be collected during the last 4 min of each standardized 15-minute block to estimate carbohydrate and fat oxidation. A fingerprick blood lactate and blood glucose sample will be collected at the end of each 15-minute block. Ratings of perceived exertion will also be taken at the end of each block. Water will be available ad-libitum during the first test day and will be quantified. The same amount of water will be provided for the remaining trial. After completion of the 60-minute simulated soccer game, we will test physical performance using a repeated sprint ability test comprised of twelve, 30m sprints with 35sec of walking recovery between each sprint. Subsequently, technical skills will be assessed using a battery test comprised of the Slalom Dribble test and the Loughborough Soccer Passing Test (LSPT). The Slalom Dribble test is a skill test that requires participants to dribble a soccer ball around a set obstacle course taking the least amount of time possible whereas the LSPT is a test that requires participants to accurately pass a soccer ball a set number of times towards coloured targets while negotiating a coned area, as quickly as possible.