The effect of a low glycemic vs. high glycemic pre-exercise meal in recreationally trained endurance cyclists
The purpose of this study was to examine the effects of two iso-kilocaloric (837.2 kJ) pre-exercise meals: A low glycemic meal (LGM) vs. a high glycemic meal (HGM) and a placebo meal in recreational cyclists on endurance cycling. After a 2-d high carbohydrate diet and abstention from exercise, 18 healthy recreationally trained male subjects aged 18 to 35 yrs with a VO2 max of 3.94 ± 0.6 L·min-1 participated in this within-subject design study. Each of three rides consisted of 2 hr of cycling exercise at 55% VO2 max followed by a brief 30 min rest and a moderately high intensity ride to exhaustion at 80% VO2 max. The LGM did not exert a greater ergogenic effect in this study when compared to the iso-kilocaloric HGM. While the effect was not statistically significant, the HGM meal outperformed the LGM and the placebo on time to exhaustion. A fiber-free, glucose-derived meal may be superior to a low glycemic fiber-free whole meal in supporting moderately high intensity exercise in some highly motivated recreationally trained endurance athletes.