This study tested whether taking whey protein together with collagen peptides would provide greater benefits for muscle and bone health compared to whey protein alone, collagen alone, or a placebo. Forty healthy, resistance-trained men aged 18-35 years were randomly assigned to one of four groups: (1) whey protein plus collagen (30 g + 10 g/day), (2) whey protein only (30 g/day), (3) collagen only (10 g/day), or (4) placebo (maltodextrin). All participants followed a supervised resistance training program (3 times per week) for 8 weeks.

The primary outcome was muscle mass, measured with bioelectrical impedance analysis (BIA). Secondary outcomes included bone mineral density (DXA scans), maximal strength (1RM squat and bench press), and blood markers of bone turnover (P1NP and CTX-I).

Results showed that the whey + collagen group achieved the largest improvements in muscle growth, lumbar spine bone mineral density, strength, and favorable changes in bone turnover markers compared to all other groups. No serious side effects were reported, and supplement adherence was very high.

These findings suggest that combining whey protein and collagen may be a practical strategy to support muscle and bone adaptation in resistance-trained men.

This was a double-blind, randomized, placebo-controlled trial evaluating the combined effects of whey protein and collagen supplementation on muscle mass, bone mineral density (BMD), muscular strength, and bone turnover markers in resistance-trained men.

Forty healthy male participants (18-35 years, with ≥1 year of resistance training experience) were recruited and randomized into four parallel groups (n=10 per group):

Whey Protein + Collagen (30 g WP + 10 g collagen/day)

Whey Protein only (30 g/day)

Collagen only (10 g/day)

Placebo (10 g maltodextrin/day, isocaloric)

All supplements were provided in identical single-dose sachets to ensure blinding. Participants consumed one dose upon waking and one post-exercise (or same time on rest days). A standardized, supervised hypertrophy-oriented resistance training program (3 sessions/week for 8 weeks) was applied to all groups.

Primary outcome: Muscle mass (lean body mass, assessed with BIA at baseline and 8 weeks).

Secondary outcomes: Lumbar spine and femoral neck BMD (DXA), maximal squat and bench press strength (1RM), and serum biomarkers of bone turnover (P1NP and CTX-I).

The trial was approved by the Islamic Azad University IRB (Protocol No: IAU.Ilk.C.162911421.2024). All participants gave written informed consent. Compliance with supplementation was >90% and training adherence was >95%. No adverse events were reported.

Inclusion Criteria:

• Male participants aged 18-35 years
• At least 1 year of consistent resistance training experience (≥3 sessions per week, targeting major muscle groups)
• Healthy, with no history of musculoskeletal, metabolic, or cardiovascular disorders
• No current or recent (<6 months) use of anabolic steroids, growth hormones, or performance-enhancing substances
• Non-smoker and no habitual use of anti-inflammatory medications
• Able and willing to comply with supplementation and supervised training program
• Provided written informed consent

Exclusion Criteria:

• Participation in similar supplementation studies in the past 6 months
• Recent fractures or surgeries affecting musculoskeletal health (<6 months)
• Known allergy or intolerance to dairy proteins or collagen supplements
• Inability to attend scheduled supervised resistance training sessions
• Non-adherence to dietary control requirements (e.g., use of additional protein/creatine supplements during study)
• Any condition deemed by investigators to interfere with study compliance or safety

De-identified individual participant data (IPD) that support the findings of this study will be made available to qualified researchers upon reasonable request from the corresponding author. Requests will require approval by the Islamic Azad University Institutional Review Board to ensure compliance with ethical and data protection regulations. Supporting documents such as the study protocol and statistical analysis plan will also be available. Data will be shared beginning 6 months after publication of the study results and remain accessible for 5 years.

De-identified IPD, study protocol, and statistical analysis plan will be available starting 6 months after publication of the trial results. Data will remain available for a period of 5 years thereafter.

Qualified academic and clinical researchers may request access to de-identified participant data, along with the study protocol and statistical analysis plan. Requests must be submitted in writing to the corresponding author and will be reviewed by the research team in consultation with the Institutional Review Board. Access will be granted for scientifically valid proposals. Data will be shared through secure transfer methods in compliance with data protection regulations.

Double-blind design extended to all relevant parties. Supplements were provided in identical, opaque sachets to ensure concealment. Randomization sequence was managed by an independent statistician not involved in data collection or analysis. Participants, trainers, investigators, and outcome assessors remained blinded to group assignments until completion of analyses.