Effects of previous carbohydrate supplementation on muscular fatigue: double-blind, randomized, placebo-controlled crossover study

Abstract

The aim of this study was to examine the effects of previous carbohydrate supplementation on high-volume resistance exercise performance. Methods: Twenty males physically independent adults aged ≥18 years participated in a double-blind randomized placebo-controlled crossover study. Sixty minutes before the experimental protocol, each participant ingested 0,6 g.kg of body mass-1 of carbohydrate supplementation or placebo. Maximum voluntary isometric contraction tests were performed before and after the dynamic fatigue induction protocol consisting of 10 sets of 8 repetitions of right leg knee extensors at 120º s-1. Results: Lower decrement of the isometric peak torque (p<0,001) and of the rate of torque development (p<0,001) was observed in carbohydrate supplementation after the dynamic protocol. Both concentric and eccentric peak torque differed significantly (p<0,001) between carbohydrate supplementation and placebo treatments from the second set, although the slope of the force-repetitions curve was not different between them. Additionally, the carbohydrate supplementation resulted in a lower session rating of perceived exertion (p<0,05). Conclusions: Previous carbohydrate supplementation attenuates muscle fatigue and internal load exercise in a high-volume isokinetic leg protocol.

The Ergogenic Effects of Acute Carbohydrate Feeding on Resistance Exercise Performance: A Systematic Review and Meta-analysis

“…There was a range of RT experience with some studies requiring a minimum 2-6 months of training experience [41,42,69]; whereas others reported participant cohorts with more than 5 years RT experience [34,35,38,44,45]. Participants in four studies were recreationally trained or physically active [33,36,70,71] and one study did not report any information regarding training history [72]. A comprehensive description of participant characteristics can be found in Table 1.…”

“…There was a variety of loading schemes from 10 to 100% of 1 − RM, and the total number of sets (including submaximal) completed per session ranged from 3 to 34. Four studies included isokinetic exercise, of which one was knee extension [36] and three were knee extension and flexion [34,35,72]. One study [34] included isokinetic contractions in addition to a lower body free-weight RT session.…”

“…All studies that delivered CHO as a liquid beverage or semi-solid meal used a simple, powdered CHO source such as maltodextrin, dextrose/glucose, or fructose. For the comparator condition, 18 studies reported using a low/noncaloric placebo; however, two studies did not explicitly provide information regarding the caloric content of the placebo beverage [33,72]. One study used a water-only control condition [74] and one study used both a placebo and water-only control as comparator conditions [75].…”

“…These pre-trial fasting durations clustered at each end of the range with nine studies using a 2-to 4-or 10-to 12-h fast duration, respectively. The fast duration of two studies was unclear [70,72].…”

“…The remaining studies stated the trial was randomised but did not report a randomisation method or information regarding allocation concealment and were rated with some concerns. In the domain assessing risk of bias related to period and carry-over effects, three studies [32,71,72] did not report the wash-out length and were rated as having some concerns. The remaining studies reported a sufficient wash-out period (at least 72 h) and were rated as having a low risk of bias.…”