The effect of daily resistance training scheduling and caffeine supplementation on training-induced adaptations in men who perform recreational resistance training

The primary aim of this study is to determine the independent and interactive effects of training time of day and caffeine supplementation on resistance training-induced changes in skeletal muscle hypertrophy, body composition, maximal strength, muscular endurance, and neuromuscular performance.

A randomized, double-blind, placebo-controlled, parallel-group, phase 3 study on 100 men. The RAND function of Excel will be used for randomization.

One hundred caffeine-naive, recreationally resistance-trained men will be randomly assigned to CAFRTm, PLARTm, CAFRTe, or PLARTe. Following a familiarization session, participants will complete 12 weeks of supervised resistance training (3 sessions/week; 70–85% 1RM). The study will be conducted in Ankara, Turkey.

Inclusion criteria: recreationally resistance-trained men with 6-12 months of experience; aged between 18 and 35 years; naïve-caffeine consumers. Exclusion criteria: suffering from pathology or injury, using medications, supplements, or ergogenic aids, and missing >5% of training trials.

1. caffeine (4 mg/kg) plus resistance training in the morning (CAFRTm); 2. placebo plus resistance training in the morning (PLARTm); 3. caffeine (4 mg/kg) plus resistance training in the evening (CAFRTe); or 4. placebo plus resistance training in the evening (PLARTe).

Body composition, muscle morphology, and muscular strength will be assessed at pre-test and post-test.

To minimize potential differences between groups, participants will first be grouped based on their average 1-rep maximum strength in the back squat and bench press. The names of the subjects in each group will be entered into an Excel column; each subject will be randomly assigned a number using the RAND function; then, the numbers will be sorted from smallest to largest. Subjects in each group will then be randomly assigned to one of four groups in a 1:1:1:1 ratio: caffeine plus exercise in the morning, placebo plus exercise in the morning, caffeine plus exercise in the evening, or placebo plus exercise in the evening.

Someone outside the study will prepare the supplement and placebo and will not be known to the participants or researchers until after the data analysis. Also, subjects will receive the supplement and placebo in an opaque capsule with a completely similar appearance and weight, and at the same time of day.

All data collected during the study will be shareable after de-identifying the subjects.

The data will be published after the extracted articles are accepted.

All people

All data collected during the study will be shareable after de-identifying the subjects. The requester will only be permitted to use the data for meta-analysis reviews.

Corresponding author: Davar Khodadadi, Faculty of Physical Education and Sports Sciences, Islamic Azad University Central Tehran Branch, Tehran, Iran. Email: davar.khodadadi@yahoo.com

Sending an email request to the corresponding author: Davar Khodadadi, Email: davar.khodadadi@yahoo.com