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Caffeine and vitamin c may fight mental fatigue to improve strength — a trial puts the combo to the test

NCT ID NCT07726745

Symptom relief Sponsor: Yunliang Zhang Source: ClinicalTrials.gov ↗

What the study statuses mean

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Recruitment status, easiest to join first

Recruiting now
This trial is taking on new participants right now.
Not yet recruiting This study
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Jul 24, 2026 · Last updated Jul 28, 2026 · Updated 2 times

Summary

This trial investigates whether caffeine, vitamin C, or their combination can improve maximum strength and strength endurance in female adolescents experiencing mild mental fatigue. Forty healthy college students will complete strength tests after a mental fatigue task, with each participant trying all supplement conditions in a random order. The study aims to see if these common substances can counteract the physical effects of mental tiredness.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
caffeine and vitamin C
What this could lead to
If effective, a simple combination of caffeine and vitamin C could help counteract mental fatigue and improve physical performance in young athletes.
What could go wrong
This is a small, early-stage trial in healthy female college students, so results may not apply to other groups. Caffeine can cause side effects like jitters or sleep disruption.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Not a phased trial

Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.

Participants

About 40 people

The number the study aims to enrol. It can still change while the study runs.

Expected to start

Jul 2026

An estimate. Start dates often move.

Expected to finish

Sep 2026

An estimate. End dates often move.

Lead sponsor

Other sponsor

The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 to 19 years

Sex

Female participants only

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Aged between 18and 19years (adolescent) 2. Able to complete standardized 1RM maximal strength test and muscular endurance protocol for back squat and bench press 3. Meet criteria for mild mental fatigue verified by validated scale (PVT + VAS Mental Fatigue ≥4/10 or Brief Fatigue Inventory) prior to experimental session 4. Habitual daily caffeine intake ≤ 150 mg/day (low-to-moderate habitual consumption) 5. Non-smoker; no regular alcohol consumption 6. Consistent strength training status: No physical training for the past 3 months, or maintenance of a consistent daily activity routine throughout the study 7. Able to attend all scheduled testing visits, comply with pre-test restrictions (diet, sleep, exercise, supplements) 8. Participant provides written assent; parent/legal guardian provides written informed consent 9. Able to understand and follow verbal and written study instructions Exclusion Criteria: 1. History of cardiovascular disease, arrhythmia, hypertension, asthma requiring regular medication 2. Known hypersensitivity or adverse reaction to caffeine, vitamin C 3. Chronic neurological disorders: epilepsy, migraine disorder, ADHD with stimulant medication 4. Current psychiatric diagnosis (anxiety, depression) receiving psychotropic medication 5. Musculoskeletal injury in the past 3 months limiting lower/upper body maximal strength testing 6. Regular intake of ergogenic supplements (creatine, beta-alanine, energy drinks) within 4 weeks before screening 7. Use of any stimulants, anti-fatigue drugs, corticosteroids within 30 days prior to enrollment 8. Chronic gastrointestinal disease, kidney stone history (vitamin C related risk) 9. Irregular sleep-wake cycle, diagnosed sleep disorder 10. Females: current pregnancy; regular oral contraceptive use 11. Participated in other human intervention trials within past 8 weeks 12. Investigator judges any condition that compromises participant safety or interferes with outcome measurements

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Conditions

The condition(s) this trial relates to.

Mental Fatigue

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Maximum force Mental fatigue Strength endurance

How to take part

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  1. The official record

    ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.

    Open the record ↗

  2. A doctor treating you

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