The Effects of Caffeine and Vitamin C on Maximum Strength and Strength Endurance in Adolescents W… (NCT07726745) | Clinical Trial Compass
Not Yet RecruitingNot Applicable
The Effects of Caffeine and Vitamin C on Maximum Strength and Strength Endurance in Adolescents With Mild Mental Fatigue
40 participantsStarted 2026-07-25
Plain-language summary
Objective To investigate the independent and combined effects of caffeine and vitamin C on maximal strength and strength endurance in female adolescents with mild mental fatigue.
Methods A randomised, double-blind, crossover experimental design was adopted. Forty female college students presenting mild mental fatigue were recruited as participants. Each participant completed five laboratory sessions in total. The first session determined their one-repetition maximum (1RM) for bench press and back squat. The remaining four experimental sessions involved four supplement interventions administered in random order: placebo control, vitamin C (VC) alone, caffeine (CAF) alone, and combined caffeine plus vitamin C (CAF+VC). A one-week washout interval was arranged between every two supplementation trials.
In each test session, participants completed a 45-min Stroop task to induce mental fatigue prior to exercise assessments. Measurements included the Visual Analogue Scale for Mental Fatigue (VAS-MF), 1RM bench press and squat performance, as well as the maximal number of repetitions at 65% 1RM for both movements. Immediately after the strength endurance test, perceived exertion and muscle pain were rated. Blood glucose and blood lactate concentrations were sampled before and after all exercise protocols.
Supplementation was administered 1 hour prior to testing: a standard caffeine dosage of 3.0 mg per kg body mass and a single 500 mg dose of vitamin C were provided for the corresponding intervention groups.
Who can participate
Age range
18 Years – 19 Years
Sex
FEMALE
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
. Aged between 18and 19years (adolescent)
. Able to complete standardized 1RM maximal strength test and muscular endurance protocol for back squat and bench press
. Meet criteria for mild mental fatigue verified by validated scale (PVT + VAS Mental Fatigue ≥4/10 or Brief Fatigue Inventory) prior to experimental session
. Consistent strength training status: No physical training for the past 3 months, or maintenance of a consistent daily activity routine throughout the study
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
1RM Squats and Bench Presses；Number of repetitions for 65% 1RM squats and bench presses