This randomized, double-blind, placebo-controlled crossover trial investigates the effects of three different caffeine supplementation strategies on resistance training-induced adaptations in 180 caffeine-naive, inactive young adult males. Participants will undergo two 4-week supervised resistance training programs separated by a 2-week washout/crossover period. The three caffeine strategies are: (1) constant daily low-moderate dosing (3 mg/kg/day), (2) gradually escalating dose (3 to 6 mg/kg across weeks), and (3) training-day-only caffeine (3 mg/kg/day). Primary outcomes include non-invasive measures of integrated anabolism and hypertrophy (D2O-derived plasma proteomic fractional synthesis rate, DXA muscle volume) and strength metrics. Secondary outcomes include hormonal responses (insulin, cortisol, testosterone, IGF-1), sleep/recovery parameters, and adverse effects.
Who can participate
Age range
18 Years – 30 Years
Sex
MALE
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* Male sex and age between 18-30 years
* No history of caffeine use or very low habitual intake (\<50 mg/day)
* No participation in a regular resistance training program in the past 6 months
* Body mass index (BMI) between 18.5-30 kg/m2
* Willingness to attend all training and testing sessions regularly
* Provision of written informed consent after being fully informed about the study
Exclusion Criteria:
* Presence of cardiovascular, metabolic, renal, hepatic, or other serious chronic diseases
* Diagnosed psychiatric disorders or severe caffeine intolerance/allergy
* Use of medications affecting caffeine metabolism or muscle anabolism (e.g., beta-blockers, antidepressants, anabolic steroids)
* Musculoskeletal injuries that prevent safe resistance training
* Smoking or alcohol consumption at levels that could affect study outcomes
* Concurrent participation in another exercise intervention study
* Inability to tolerate DXA scanning, blood sampling, or D2O ingestion procedures
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Change in Plasma Proteomic Fractional Synthesis Rate (FSR)
Timeframe: Baseline; End of Intervention Period 1 (Week 4); End of Intervention Period 2 (Week 4)
2
Change in Lean Body Mass Measured by DXA
Timeframe: Baseline; End of Intervention Period 1 (Week 4); End of Intervention Period 2 (Week 4)
3
Change in Muscle Volume Measured by DXA
Timeframe: Baseline; End of Intervention Period 1 (Week 4); End of Intervention Period 2 (Week 4)
4
Change in Maximal Strength Assessed by 1RM/3RM Tests
Timeframe: Baseline; End of Intervention Period 1 (Week 4); End of Intervention Period 2 (Week 4)
5
Total Training Volume Load
Timeframe: Intervention Period 1 (Weeks 1-4); Intervention Period 2 (Weeks 1-4)