High versus low carbohydrate in Skimo race performance: a randomized controlled trial

Abstract

Ski mountaineering (skimo) is a high-intensity sport with several race disciplines of varying lengths in which competitors face many challenges that can make consuming food and fluids difficult. There is currently a scarcity of literature on skimo, particularly on nutrition in individual-format races. Exercise >1.5 h, as in an individual skimo race, may benefit from high carbohydrate consumption of > or = 90 g/h compared to lower recommendations of 60 g/h. However, gastrointestinal upset is worsened with increasing amounts of carbohydrate consumption, especially during high-intensity exercise. Highly-branched cyclic dextrin is a glucose polymer with a low osmolality allowing it to have a fast gastric emptying rate which can decrease gastrointestinal upset during exercise. The first purpose of this study was to survey skimo athletes about their nutrition knowledge and practices. With this new information combined with recommendations on carbohydrate and fluid intake, the second purpose of this study was to test an 18% solution of highly-branched cyclic dextrin + fructose (3:1) in a skimo race. It was hypothesized that an 18% solution (90G) would improve performance in an individual race compared to a 6% solution (30G) without contributing to gastrointestinal upset. Fifteen participants completed the randomized controlled crossover trials. Average carbohydrate consumed was 27 and 85 g/h and race time 105 and 107 min in 30G and 90G, respectively. Overall race times were not significantly different. Gastrointestinal upset trended higher in 90G (p=0.07). When the four participants with high gastrointestinal upset (rating >4/10) were removed from analysis, there was a main effect for drink on percent lap time change (p<0.001), with 30G having a greater percent increase in lap time throughout the trial. In conclusion, a high-carbohydrate drink was created to address the needs of skimo athletes. It was found that an 18% carbohydrate solution had significantly higher gastrointestinal upset ratings and did not confer additional performance benefit compared to a 6% solution. Additionally, high gastrointestinal upset with the 18% solution appears to have contributed to slower time; however, those without high gastrointestinal upset with the 18% solution had a lesser percentage change in lap time throughout the trial compared to 6%.