Resistance Training Adaptations and Caffeine Intake

Summary

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.

Conditions

• Muscle Hypotrophy
• Exercise Performance
• Muscle Strength
• Adaptation

Interventions

DIETARY_SUPPLEMENT

Caffeine (Constant Daily Dose)

Oral caffeine capsule at 3 mg/kg body weight, consumed daily approximately 60 minutes before training sessions (on training days) or at the same time of day (on rest days).

DIETARY_SUPPLEMENT

Placebo (Constant Daily Dose)

Identical-appearing placebo capsule consumed at the same times as the caffeine intervention.

DIETARY_SUPPLEMENT

Caffeine (Escalating Dose)

Oral caffeine starting at 3 mg/kg/day and increasing incrementally to reach 6 mg/kg/day by week 4.

DIETARY_SUPPLEMENT

Placebo (Escalating Dose)

Placebo capsule daily for 4 weeks with simulated dose escalation protocol, then crossover to escalating caffeine after 2-week washout.

DIETARY_SUPPLEMENT

Caffeine (Training Days Only)

Oral caffeine capsule at 3 mg/kg body weight, consumed only on training days approximately 60 minutes before exercise.

DIETARY_SUPPLEMENT

Placebo (Training Days Only)

Placebo capsule only on training days for 4 weeks, then crossover to caffeine after 2-week washout.

Sponsors & Collaborators

• İstanbul Yeni Yüzyıl Üniversitesi

  collaborator OTHER

• Istanbul University - Cerrahpasa

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

30 Years

Sex

MALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-02-20

Primary Completion

2026-04-20

Completion

2026-04-20

Countries

• Turkey (Türkiye)

Study Locations