Carbohydrate loading and supplementation in endurance-trained women runners.
The purpose of this study was to examine the effect of carbohydrate (CHO) augmentation on endurance performance and substrate utilization in aerobically trained women. Eight endurance-trained women completed a 24.2-km (15 mile) self-paced treadmill performance run under three conditions: CHO supplementation (S), CHO loading and supplementation (L+S), and placebo (P). Dietary CHO was approximately 75% of energy intake for L+S and approximately 50% for both S and P. A 6% CHO-electrolyte solution (S and L+S) or placebo (P) was ingested preexercise (6 ml/kg) and every 20 min during exercise (3 ml/kg). Blood glucose was significantly higher at 40, 60, and 100 min during L+S, and at 60, 80, and 100 min during S compared with P (P < 0.05). Blood lactate was significantly higher (P < 0.05) during L+S than S and P. Blood glycerol was significantly lower (P < 0.05) at 20, 80, and 100 min during L+S, and at 80 and 100 min during S than P. The proportion of CHO (%) utilized during exercise was significantly higher (P < 0.05) during L+S (71.3 +/- 3.8%) and S (67.3 +/- 4.3%) than P (59.2 +/- 4.6%). Performance times (P > 0.05) were 132.5 +/- 6.3 min (S), 134.4 +/- 6.3 min (L+S), and 136.6 +/- 7.9 min (P). In conclusion, it appears that when CHO availability in women is increased through CHO loading and/or CHO supplementation, there is a concomitant increase in CHO utilization. However, this may not necessarily result in significantly improved performance.
Andrews
Jessica L
JL
Department of Health and Kinesiology, Purdue University, W Lafayette, IN 47907-2046, USA.
Sedlock
Darlene A
DA
Flynn
Michael G
MG
Navalta
James W
JW
Ji
Hongguang
H
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000378:metabolism; D019587:Dietary Supplements; D004326:Drinking; D005260:Female; D005767:Gastrointestinal Diseases / Q000209:etiology; D005990:Glycerol / Q000097:blood; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D010807:Physical Endurance; D005082:Physical Exertion; D012420:Running; D012649:Self Concept; D013997:Time Factors; D015431:Weight Loss
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D019344:Lactic Acid; D005990:Glycerol