The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review

Abstract

High carbohydrate intakes are commonly recommended for athletes of various sports, including strength trainees, to optimize performance. However, the effect of carbohydrate intake on strength training performance has not been systematically analyzed. A systematic literature search was conducted for trials that manipulated carbohydrate intake, including supplements, and measured strength, resistance training or power either acutely or after a diet and strength training program. Studies were categorized as either (1) acute supplementation, (2) exercise-induced glycogen depletion with subsequent carbohydrate manipulation, (3) short-term (2–7 days) carbohydrate manipulation or (4) changes in performance after longer-term diet manipulation and strength training. Forty-nine studies were included: 19 acute, six glycogen depletion, seven short-term and 17 long-term studies. Participants were strength trainees or athletes (39 studies), recreationally active (six studies) or untrained (four studies). Acutely, higher carbohydrate intake did not improve performance in 13 studies and enhanced performance in six studies, primarily in those with fasted control groups and workouts with over 10 sets per muscle group. One study found that a carbohydrate meal improved performance compared to water but not in comparison to a sensory-matched placebo breakfast. There was no evidence of a dose-response effect. After glycogen depletion, carbohydrate supplementation improved performance in three studies compared to placebo, in particular during bi-daily workouts, but not in research with isocaloric controls. None of the seven short-term studies found beneficial effects of carbohydrate manipulation. Longer-term changes in performance were not influenced by carbohydrate intake in 15 studies; one study favored the higher- and one the lower-carbohydrate condition. Carbohydrate intake per se is unlikely to strength training performance in a fed state in workouts consisting of up to 10 sets per muscle group. Performance during higher volumes may benefit from carbohydrates, but more studies with isocaloric control groups, sensory-matched placebos and locally measured glycogen depletion are needed.

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

“…Our findings contrast and agree with the findings of a recent systematic review by Henselmans et al [47], which found that the majority of studies assessing the effects of acute CHO ingestion on RT performance reported no ergogenic effect. There are differences in study inclusion criteria and outcomes of interest that may explain the differences in our findings.…”

“…We have also conducted various sub-group and meta-regression analyses to control for potential confounders. Nonetheless, there is some agreement in results, as Henselmans et al [47] note that CHO ingestion may be beneficial in some circumstances such as fasted training and higher training volumes (< 10 sets per muscle group). This finding by Henselmans et al [47] agrees with the findings of our current metaanalysis in which CHO ingestion improves RT volume performance for longer session durations (> 45 min) and fast durations (≥ 8 h).…”

“…There are differences in study inclusion criteria and outcomes of interest that may explain the differences in our findings. Specifically, the current review exclusively included cross-over trials comparing CHO ingestion to a zero-to-low kcal (≤ 25 total kilocalories) placebo or wateronly control; whereas, the review by Henselmans et al [47] additionally included parallel trials, and isocaloric comparator conditions. It is important to note that the analysis by Henselmans et al [47] broadly and qualitatively assessed the effects of CHO ingestion on various RT outcomes, whereas we have used meta-analysis to specifically quantify the magnitude of the effects of CHO on RT volume performance.…”

“…Thus, while there seems to be a general trend for CHO ergogenicity that is dependent on RT session duration, these findings are not consistent and are at times contradictory. Recently, a systematic review by Henselmans et al [47] concluded that while the majority of studies investigating the acute effects of CHO ingestion on RT performance did not find a positive effect, there was a trend where studies with longer pre-exercise fast durations and RT protocols of greater than 10 sets completed reported an ergogenic effect of CHO ingestion. However, it is important to note that a quantitative analysis of specific RT outcomes was not conducted.…”

Protein O-GlcNAcylation in Metabolic Modulation of Skeletal Muscle: A Bright but Long Way to Go

“…The metabolic flexibility of skeletal muscle allows it to increase energy supply and provide sufficient “fuel” for contraction [ 64 , 65 ]. The importance of carbohydrate as a fuel source in exercise has been known, and the main source of these carbohydrate is glycogen reserve of skeletal muscle during exercise [ 66 , 67 ]. In addition, skeletal muscle actively secretes myogenic protein to exert autocrine, paracrine or endocrine functions to convey its energy demand to other organs, including adipose tissue, the liver, pancreas, cardiovascular system, brain, bone and skin, thus causing crosstalk [ 68 , 69 ].…”