Effects of Pre-exercise Nutrient Timing on Glucose Responses and Intermittent Exercise Performance

Abstract

PURPOSE: To evaluate the effects of two different pre-exercise feeding schedules (15 and 60 minutes) of a mixed-nutrient nutritional bar, on blood glucose levels and subsequent intermittent high-intensity exercise performance. METHODS: 10 moderately trained athletes participated in this counterbalanced, cross-over, repeated measures study. Participants completed a 50-minute counterbalanced treatment, intermittent exercise protocol. During one trial, participants consumed 400ml of water and a standardized, nutritional bar 15 minutes before the exercise session (15 MPE). During another trial, participants consumed 400ml of water and a standardized, nutritional bar 60 minutes before the exercise session (60 MPE). During another trial (CON), participants consumed 400 ml of water. RESULTS: There were no significant differences in plasma glucose response at rest, or during exercise among the three treatments (CON, 15MPE, and 60MPE) (Figure1). There were no significant differences in mean power (MP) between the three trials (Figure 2).In conclusion, pre-exercise nutrient feedings at 15 minutes, or 60 minutes before exercise did not affect intermittent cycling performance or blood glucose. CONCLUSIONS: These results suggest that the timing of ingestion of a complex carbohydrate similar in composition and volume to that tested herein; in the hour prior to exercise does not seem to impact performance.