Carbohydrate supplementation during cycling exercise
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Enhancing cycling exercise performance through means of carbohydrate supplementation suggests that a blend of multiple transportable carbohydrate (CHO) sources supplemented at a feeding rate of 78 g•h -1 will provide optimal performance and attenuate gastrointestinal discomfort during exercise. PURPOSE: To determine if the literature suggested feeding rate (78 g•h-1) applies to variable and relatively high intensity cycling exercise; and to determine if a unique high molecular weight starch fraction (VitargoRTM; Swecarb, Sweden) provides an advantage over the literature ideal (multiple transportable CHO). METHODS: Six competitive male cyclists and triathletes (mean age 25.6 +/- 4.4 years; mean weight 77.56 +/- 7.3 kg; mean VO2max 59.57 +/- 8.47 mLs•kg-1•min-1) volunteered in the randomized double blind study. Each participant completed 3 randomized, 90-min cycling time trials with various stages (3 distinct flats and 3 distinct mountains) while ingesting the following CHO solutions: 1:1:1 maltodextrin-fructose-glucose at 117 g•h-1 (HDMD), 1:1:1 maltodextrin-fructose-glucose at 78 g•h-1 (LDMD), or a single source high molecular weight starch fraction (Vitargo) at 117 g•h -1 (HDV.) Each CHO solution had an identical electrolyte composition (18 mmol•L-1 Na, 3 mmol•L-1 K, and 11 mmol•L-1 Cl). RESULTS: Independent of CHO type, power (W) was significantly greater during the final flat stage (p = .01) compared to the first 2 flat stages and significantly greater during the first mountain stage (p = .01) compared to the final 2 mountain stages. However, power (W) was not significantly different between CHO supplement types across the stages. Independent of CHO type, respiratory exchange ratio (RER) was significantly different across all flat stages ( p = .01). However, RER was not significantly different between CHO supplement types across the flat stages. CONCLUSION: During variable intensity cycling, there does not appear to be a performance or metabolic advantage to supplementing multiple transportable CHO at 78 g•h -1 compared to the same multiple transportable CHO blend at a feeding rate 117 g•h-1. Additionally, there does not appear to be disadvantage to supplementing with a single source, high molecular weight starch fraction (Vitargo), despite the literature suggestion of using CHO solutions having multiple transportable CHO sources.;Keywords: multiple transportable carbohydrate; carbohydrate ingestion rate; cycling.