The effectiveness of a natural carbohydrate source (sun-dried raisins) versus sports jelly beans on prolonged cycling performance

Abstract

PURPOSE: This study was designed to examine the effects of sun-dried raisins versus sports jellybeans on endurance performance in trained cyclists/triathletes. METHODS: Ten healthy males (18-33 y) completed one water-only acclimatization (WAT) exercise trial and two randomized exercise trials. Each trial consisted of a 120-minute constant intensity glycogen depletion period followed by a 10-km time trial (TT). During each experimental trial, participants consumed isocaloric amounts of sun-dried raisins (SDR) or Sports Jelly Beans(SJB) in 20-minute intervals. Measurements included: time to complete 10-km TT, power output during 10-km TT, blood glucose levels and respiratory exchange ratio (RER) during glycogen depletion period, RPE, ‘flow’ questionnaire responses, and sensory acceptance. RESULTS: There were no significant differences in endurance performance between any of the trials. Resting blood glucose levels were not significantly different between any of the trials and both CHO supplements were equally effective in maintaining blood glucose levels during the 120-min exercise bout compared to the WAT acclimatization trial (4.3 ± 0.3 mmol/L for WAT, 5.8 ± 0.4 mmol/L for SDR, and 5.4 ± 0.2 mmol/L for SJB). There were no significant differences in RPE or flow experiences between trials. Mean sensory acceptance scores were significantly higher for the SDR compared to the SJB (50.7 ± 1.7 for SDR and 44.3 ± 2.7 for SJB). CONCLUSIONS: Consuming SDR or SJB during 120 min of intense cycling result in similar time-trial performances and are equally effective in maintaining blood glucose levels during exercise.