Exogenous Carbohydrate Form During Low-Muscle Glycogen Conditions Has Minimal Impact on Cycling Performance

Abstract

Background: Skeletal muscle recovery is improved with immediate postexercise carbohydrate feeding. Little is known regarding muscle recovery and performance when feeding is delayed. The purpose of this study was to examine the effects of varying exogenous carbohydrates on cycling performance with delayed feedings and low skeletal muscle glycogen content.

Methods: Following 60 min of cycling and an overnight fast (12.1 ± 0.4 h), the participants consumed 2.10 ± 0.13 g·kg−1 bodyweight carbohydrate of one of the following: whole potatoes (POT), cooked pasta (PAS), energy gel (GEL) or remained unfed (control, CON), then rested for 120 min. The participants then cycled for 60 min at 65% Wmax and completed a 19.4 km time trial. Muscle and blood samples were collected prefeeding, 120 min postfeeding, and after cycling for glycogen, glucose, and insulin analyses.

Results: The time trial mean power output was higher in the PAS (213 ± 56W, p = 0.006) and GEL (209 ± 71W, p = 0.011) compared to CON (179 ± 68W), but POT (196 ± 51W, p = 0.199) was not different from CON. Power was similar between POT, PAS, and GEL (p > 0.05). Time trial finish time trended towards significance (p = 0.088) with carbohydrate trials averaging 3 min faster than CON. Muscle glycogen was similar between trials (p = 0.446) and did not change due to feeding (prefeeding: 44 ± 21 mmol·kg−1, postfeeding: 47 ± 23 mmol·kg−1, p = 0.120). Glycogen declined after cycling for 60 min (26 ± 16 mmol·kg−1, p < 0.001) compared to pre-feeding and post-feeding samples. Glucose and insulin were elevated in carbohydrate trials over CON 0–30 min postfeeding (p < 0.05).

Conclusions: Varied pre-exercise exogenous carbohydrate sources effectively improve cycling time trial performance in a glycogen compromised state.

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