Submitted on September 19, 2002
Accepted on April 17, 2003
Carbohydrate loading and supplementation in endurance trained women runners
Jessica L Andrews1, Darlene A Sedlock1*, Michael G Flynn1, James W Navalta1, and Hongguang Ji2
1 Wastl Human Performance Laboratory, Department of Health & Kinesiology, Purdue University, W. Lafayette, IN, USA
2 Department of Nautical Hygiene, Faculty of Naval Medicine, Second Military Medical University, Shanghai, China
* To whom correspondence should be addressed. E-mail: sedlock{at}purdue.edu.
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 mi) self-paced treadmill performance run under three conditions: CHO supplementation (S), CHO loading and supplementation (L+S), and placebo (P). Dietary CHO was ~75% of energy intake for L+S and ~50% for S and P. A 6% CHO-electrolyte solution (S and L+S) or placebo (P) was ingested pre-exercise (6 ml.kg-1) and every 20 min during exercise (3 ml.kg-1). Blood glucose was significantly higher at 40, 60, and 100 min during L+S, and at 60, 80, and 100 min during S compared to 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.
