Muscle Hypertrophy, Strength
Conditions
Keywords
Resistance training, Carbohydrate supplementation, Energy intake, Muscle hypertrophy, Muscle strength, Crossover trial
Brief summary
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.
Interventions
DIETARY_SUPPLEMENTCHO
Daily consumption of a whey protein and maltodextrin mixture providing 30 g protein, 54 g carbohydrate, and 2 g fat per 92 g serving for 8 weeks
DIETARY_SUPPLEMENTPRO
Daily consumption of a whey protein blend providing 30 g protein, 4 g carbohydrate, and 2 g fat per 39 g serving for 8 weeks.
Sponsors
Auburn University
Study design
Allocation
NON_RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Masking description
Participants were blinded (supplements were provided in clear, unlabeled containers). Assessors/testers were blinded to group allocation. The ultrasound technician was blinded.
Eligibility
Sex/Gender
MALE
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
* 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
Exclusion criteria
* 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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Lean mass | Baseline, 8 weeks (mid-point), 16 weeks (post) | Bone-free lean tissue mass according to Dual-energy X-ray absorptiometry (DXA) |
| Mid-thigh muscle thickness | Baseline, 8 weeks (mid-point), 16 weeks (post) | Change in lateral thigh muscle thickness (vastus lateralis and vastus intermedius) |
| Back Squat One-Repetition Maximum | Baseline, 8 weeks (mid-point), 16 weeks (post) | Change in back squat 1RM |
| Knee Extensor Peak Torque | Baseline, 8 weeks (mid-point), 16 weeks (post) | Change in knee extensor peak torque using isokinetic dynamometry |
Countries
United States
Outcome results
None listed