Medicine & Science in Sports & Exercise:
F-22C Free Communication/Slide Carbohydrate and Performance
Davidson, C J.1; Zderic, T W.1; Schenk, S1; Walker, S L.1; Coyle, E F. FACSM1
1The Human Performance Laboratory, The University of Texas, Austin, Texas 78712
This study quantified the effect of three breakfast cereals on maximal neuromuscular cycling power during the 3h postprandial period.
Six endurance-trained cyclists [mean±SD, age:29.3±3.5y; VO2 peak:4.36±0.4L/min, peak power: 15.3±2.1 W/kg] participated. Subjects consumed one of five meals: All Bran [AB][Glycemic Index=53.8], Oatmeal [OT][GI=77.1], Cornflakes [CF][GI=112.2], a glucose solution [GLU][GI=100], or a placebo [PLA]. The three cereals and the glucose solution each contained 50g of available carbohydrate. Maximal neuromuscular power was tested, using inertial load ergometry, at three time points [30, 90 and 150 min] after the meal.
At 30 and 60 min after the feedings, plasma glucose concentration was increased significantly from PLA in all meals [AB, OT, CF, GLU; P < 0.05]. By 90 min into the experiment, plasma glucose concentration in only the CF treatment was still significantly elevated above PLA. Thereafter [120, 150 and 180 min], plasma glucose for all the treatment groups was not different from initial values. We found no main effect for treatment in maximal neuromuscular cycling power with values averaged for the 3 time points [AB:1077±40; OT:1078±43; CF:1076±40; GLU:1084±43; PLA:1090±41 W]. However, there was a main effect for time, with power increasing significantly across the three time points [30min:1065±30 <90min:1083±33; 150min:1095±32 W, P < 0.05]. Additionally, there was a significant difference between the power produced in GLU between time points 30 min [1050±78 W] and 90 min [1105±81 W, P < 0.05].
The increases in power over the 3 h period after a breakfast meal or placebo were independent of the metabolic changes presented by meals of differing glycemic response. Also, feeding a pre-exercise meal or placebo lowered maximal cycling power at 30 min compared to 90 and 150 min postprandial. Finally, a pre-exercise glucose feeding reduced maximal neuromuscular power at 30 min postprandial compared to that at 90 min. Supported by the Quaker Oats Company.