The Effect of Pre-Exercise Carbohydrate Ingestion on Maximal Neuromuscular Power During Moderate Intensity Exercise

This is the authors' abstract. We don't add key points for this paper.

This study determined if maximal neuromuscular cycling power is reduced during transient hypoglycemia caused by pre-exercise carbohydrate ingestion. Eighteen endurance-trained cyclists with a mean age, mass, height, VO2peak and lactate threshold (LT) of 29.2 ± 1.2 y, 78.8 ± 1.3 kg, 179.2 ± 1.0 cm, 4.4 ± 0.1 lmin−1 and 78.1 ± 1.1% of VO2peak, respectively, participated. Thirty-five minutes prior to exercise at 90% of LT, subjects ingested either 0.5 gkg−1 of glucose (CHO) or a sweet placebo (PLA). Insulin levels were greater and FFA levels lower in CHO vs. PLA (P < 0.05, n = 8). Plasma glucose fell to hypoglycemic levels by 14 min of exercise (3.3 ± 0.2 mM, n = 8) and remained significantly lower (P < 0.05) than PLA for the remainder of the CHO trial (3.1 ± 0.2 vs. 4.5 ± 0.2 mM mean of 14–22 min, CHO vs. PLA, respectively, n = 8). Subjects performed 4 maximal power (P MAX) tests during the 15 - 21 min period, using the inertial load method. Mean PMAX values tended to be lower (P = 0.09) in the CHO vs. PLA (1208 ± 24 vs. 1220 ± 23 W, CHO vs. PLA, respectively) trials and reached significance at sprint #2 (1207 ± 50 vs. 1232 ± 49 W, P < 0.05). In conclusion, transient hypoglycemia caused by pre-exercise carbohydrate ingestion may slightly impair maximal neuromuscular power in trained cyclists at certain time points.