Effects of Carbohydrates Versus Carbohydrates + Protein on Resistance Training Outcomes

Completed · Not applicable

Conditions studied: Muscle Hypertrophy, Strength

In brief

Higher energy and carbohydrate intakes have been hypothesized to enhance resistance training adaptations, yet empirical evidence remains mixed. This study investigated whether supplemental carbohydrate-energy intake improves muscle hypertrophy, strength, and fatigue resistance in resistance-trained men. Twenty resistance-trained men completed a quasi-randomized, double-blinded, counterbalanced crossover trial. Participants consumed either a daily protein-only supplement (30 g protein, 4 g carbohydrate) or a daily protein-plus-carbohydrate supplement (30 g protein, 54 g carbohydrate) for 8 weeks each, followed by crossover, while continuing their habitual training and diet. Primary outcomes included lean mass (dual-energy x-ray absorptiometry), muscle thickness and cross-sectional area (ultrasound), back squat one-repetition maximum, knee extensor peak torque, and fatigue index. The carbohydrate-protein supplement produced significantly higher daily energy and carbohydrate intake compared to the protein-only supplement, with no differences in protein intake, fat intake, or training volume. No significant between-condition differences were observed for any outcome. These results suggest that modest increases in carbohydrate-energy intake outside of an energy deficit are unlikely to meaningfully enhance muscle hypertrophy, strength, or fatigue resistance in trained men.

Key facts

Study ID

NCT07600138

Run by

Auburn University

People needed

25

Starts

2025-05-12

Expected to finish

2025-09-16

Last updated by the study team

2026-05-20

Who can join

Age: 18 and older, up to 40. Sex: male. Healthy volunteers: accepted.

You may qualify if…

• Male sex
• Aged 18-40 years
• BMI not exceeding 35 kg/m²
• Minimum of two years resistance training experience
• Resistance training frequency of at least four days per week
• No known allergy to whey protein supplements

You may not qualify if…

• Known cardio-metabolic disease (e.g., clinical obesity, diabetes, hypertension, heart disease)
• Any condition contraindicating participation in resistance training
• Known allergy to whey protein supplements

Where it is running

• School of Kinesiology — Auburn, Alabama, United States

Full record on ClinicalTrials.gov

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