Effects of Carbohydrates Versus Carbohydrates + Protein on Resistance Training Outcomes

NCT07600138 | Completed

• 1 other identifier: STUDY00000295
• Study Type: interventional
• Target: 25
• Locations: 1 country
• Sites: 1

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.

Conditions

Muscle Hypertrophy; Strength

Keywords

Resistance training; Carbohydrate supplementation; Energy intake; Muscle hypertrophy; Muscle strength; Crossover trial

Outcome Measures

Primary Outcomes (4)

• Lean mass

  Bone-free lean tissue mass according to Dual-energy X-ray absorptiometry (DXA)

  Baseline, 8 weeks (mid-point), 16 weeks (post)

• Mid-thigh muscle thickness

  Change in lateral thigh muscle thickness (vastus lateralis and vastus intermedius)

  Baseline, 8 weeks (mid-point), 16 weeks (post)

• Back Squat One-Repetition Maximum

  Change in back squat 1RM

  Baseline, 8 weeks (mid-point), 16 weeks (post)

• Knee Extensor Peak Torque

  Change in knee extensor peak torque using isokinetic dynamometry

  Baseline, 8 weeks (mid-point), 16 weeks (post)

Study Arms (2)

CHO

EXPERIMENTAL

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 Supplement: CHO; Dietary Supplement: PRO

PRO

ACTIVE COMPARATOR

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.

Dietary Supplement: CHO; Dietary Supplement: PRO

Interventions

CHO DIETARY_SUPPLEMENT

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

Also known as: Whey protein + CHO

CHO; PRO

PRO DIETARY_SUPPLEMENT

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.

Also known as: Whey protein only

CHO; PRO

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

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

Sponsors & Collaborators

• Auburn University: lead

Study Sites (1)

School of Kinesiology

Auburn, Alabama, 36879-5432, United States

Location

MeSH Terms

Interventions

Whey Proteins

Intervention Hierarchy (Ancestors)

Milk Proteins; Animal Proteins, Dietary; Dietary Proteins; Proteins; Amino Acids, Peptides, and Proteins; Whey; Milk; Dairy Products; Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: Participants were blinded (supplements were provided in clear, unlabeled containers). Assessors/testers were blinded to group allocation. The ultrasound technician was blinded.
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: May 15, 2026
• First Posted: May 20, 2026
• Study Start: May 12, 2025
• Primary Completion: September 15, 2025
• Study Completion: September 16, 2025
• Last Updated: May 20, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP
• Time Frame: Data are already available
• Access Criteria: Publicly available with no access restrictions

Locations

US (1)