If you’re doing a ton of sets for one muscle group (like 12+ sets of squats) or training twice in one day, eating more carbs might help you push harder — otherwise, it doesn’t matter much.
Scientific Claim
Higher carbohydrate intake may improve strength training performance during workouts exceeding 10 sets per muscle group or during bi-daily training sessions, likely due to greater glycogen depletion in type II muscle fibers.
Original Statement
“Positive effects of higher carbohydrate intakes were more consistent in higher training volume workouts. In studies with performance tests consisting of more than 10 sets per muscle group (11–17 sets), significant positive effects of higher carbohydrate intake or a trend thereof were observed in three studies...”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim implies a likely benefit, but all positive findings occurred in non-isocaloric studies. The association is suggestive but not confirmed due to confounding energy intake.
More Accurate Statement
“There is a suggestive association between higher carbohydrate intake and improved strength performance during workouts exceeding 10 sets per muscle group or bi-daily training, but findings are confounded by unequal energy intake and require isocaloric validation.”
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Randomized Controlled TrialLevel 1bWhether isocaloric carbohydrate intake improves total training volume during a high-volume resistance session (>10 sets per muscle group) compared to a matched placebo.
Whether isocaloric carbohydrate intake improves total training volume during a high-volume resistance session (>10 sets per muscle group) compared to a matched placebo.
What This Would Prove
Whether isocaloric carbohydrate intake improves total training volume during a high-volume resistance session (>10 sets per muscle group) compared to a matched placebo.
Ideal Study Design
A double-blind, randomized, crossover RCT with 25 resistance-trained individuals performing 12 sets of leg press (70% 1RM) to failure, consuming either 1.5 g/kg carbohydrate or a sensory-matched placebo (29 kcal) 2 hours pre-workout, with primary outcome: total repetitions across all sets.
Limitation: Does not assess long-term adaptations or muscle growth.
Prospective Cohort StudyLevel 2bWhether habitual high-carbohydrate intake (≥6 g/kg/day) leads to greater strength gains over 12 weeks in athletes performing high-volume training.
Whether habitual high-carbohydrate intake (≥6 g/kg/day) leads to greater strength gains over 12 weeks in athletes performing high-volume training.
What This Would Prove
Whether habitual high-carbohydrate intake (≥6 g/kg/day) leads to greater strength gains over 12 weeks in athletes performing high-volume training.
Ideal Study Design
A 12-week prospective cohort of 60 elite athletes (e.g., bodybuilders, powerlifters) performing ≥12 sets per muscle group 3x/week, consuming either 4 g/kg/day or 7 g/kg/day carbohydrates with identical protein and calories, measuring 1RM changes and muscle thickness via ultrasound.
Limitation: Cannot control for training variation or recovery behaviors.
Case-Control StudyLevel 3Whether athletes with high-volume training habits have lower intramyofibrillar glycogen depletion after training compared to low-volume athletes on similar diets.
Whether athletes with high-volume training habits have lower intramyofibrillar glycogen depletion after training compared to low-volume athletes on similar diets.
What This Would Prove
Whether athletes with high-volume training habits have lower intramyofibrillar glycogen depletion after training compared to low-volume athletes on similar diets.
Ideal Study Design
A case-control study comparing 20 high-volume athletes (≥15 sets/muscle group/week) to 20 low-volume athletes (≤6 sets/muscle group/week), matched for training status and diet, measuring muscle glycogen via biopsy after a standardized 12-set leg workout.
Limitation: Cannot determine if glycogen depletion causes performance differences — only correlates.
Evidence from Studies
Supporting (1)
The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review