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The Effects of Caffeine and Vitamin C on Maximum Strength and Strength Endurance in Adolescents With Mild Mental Fatigue

21 luglio 2026 aggiornato da: Yunliang Zhang

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.

Panoramica dello studio

Tipo di studio

Interventistico

Iscrizione (Stimato)

40

Fase

  • Non applicabile

Contatti e Sedi

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Contatto studio

Criteri di partecipazione

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Criteri di ammissibilità

Età idonea allo studio

  • Adulto

Accetta volontari sani

No

Descrizione

Inclusion Criteria:

  • (1) Healthy women aged 18 to 19; (2) No resistance training for at least three months prior to the experiment; (3) All participants had no contraindications to caffeine use and no other medical conditions; (4) Participants were prohibited from using tobacco or e-cigarettes, or from taking any medications, drugs, stimulants, or sports supplements known to interfere with gastric acid production or neuromuscular function during the trial

Exclusion Criteria:

(1) Individuals who have regularly engaged in resistance training over the past 3 months; (2) Individuals with contraindications to caffeine use or other medical conditions; (3) Tobacco or e-cigarette users, or individuals taking any medications, drugs, stimulants, or sports supplements known to interfere with gastric acid production or neuromuscular function during the trial.

Piano di studio

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Come è strutturato lo studio?

Dettagli di progettazione

  • Scopo principale: Trattamento
  • Assegnazione: Randomizzato
  • Modello interventistico: Assegnazione sequenziale
  • Mascheramento: Doppio

Armi e interventi

Gruppo di partecipanti / Arm
Intervento / Trattamento
Sperimentale: Controllo
A randomized, double-blind, crossover design was employed. Professional coaches assessed the subjects' bench press and back squat performances to examine the effects of caffeine combined with vitamin C on maximum strength (1RM) and strength endurance (repetitions to failure at 65% of 1RM) during bench press and back squat training. 65% of 1RM is a widely recognized load for strength endurance testing [28]. The formal experiment consisted of five test sessions: one for familiarization with the entire experimental procedure and a preliminary 1RM test to reconfirm the 1RM measured three weeks prior to the study. The remaining four sessions were conducted sequentially for the control group, vitamin C (VC), caffeine (CAF), and caffeine plus vitamin C (CAF+VC) groups. Each test was spaced 7 days apart to eliminate carryover effects [30]. All tests were scheduled between 12:00 PM and 4:00 PM to control for the effects of circadian rhythms [30].
Sperimentale: caf
A randomized, double-blind, crossover design was employed. Professional coaches assessed the subjects' bench press and back squat performances to examine the effects of caffeine combined with vitamin C on maximum strength (1RM) and strength endurance (repetitions to failure at 65% of 1RM) during bench press and back squat training. 65% of 1RM is a widely recognized load for strength endurance testing [28]. The formal experiment consisted of five test sessions: one for familiarization with the entire experimental procedure and a preliminary 1RM test to reconfirm the 1RM measured three weeks prior to the study. The remaining four sessions were conducted sequentially for the control group, vitamin C (VC), caffeine (CAF), and caffeine plus vitamin C (CAF+VC) groups. Each test was spaced 7 days apart to eliminate carryover effects [30]. All tests were scheduled between 12:00 PM and 4:00 PM to control for the effects of circadian rhythms [30].
Sperimentale: VC
A randomized, double-blind, crossover design was employed. Professional coaches assessed the subjects' bench press and back squat performances to examine the effects of caffeine combined with vitamin C on maximum strength (1RM) and strength endurance (repetitions to failure at 65% of 1RM) during bench press and back squat training. 65% of 1RM is a widely recognized load for strength endurance testing [28]. The formal experiment consisted of five test sessions: one for familiarization with the entire experimental procedure and a preliminary 1RM test to reconfirm the 1RM measured three weeks prior to the study. The remaining four sessions were conducted sequentially for the control group, vitamin C (VC), caffeine (CAF), and caffeine plus vitamin C (CAF+VC) groups. Each test was spaced 7 days apart to eliminate carryover effects [30]. All tests were scheduled between 12:00 PM and 4:00 PM to control for the effects of circadian rhythms [30].
Sperimentale: caf+VC
A randomized, double-blind, crossover design was employed. Professional coaches assessed the subjects' bench press and back squat performances to examine the effects of caffeine combined with vitamin C on maximum strength (1RM) and strength endurance (repetitions to failure at 65% of 1RM) during bench press and back squat training. 65% of 1RM is a widely recognized load for strength endurance testing [28]. The formal experiment consisted of five test sessions: one for familiarization with the entire experimental procedure and a preliminary 1RM test to reconfirm the 1RM measured three weeks prior to the study. The remaining four sessions were conducted sequentially for the control group, vitamin C (VC), caffeine (CAF), and caffeine plus vitamin C (CAF+VC) groups. Each test was spaced 7 days apart to eliminate carryover effects [30]. All tests were scheduled between 12:00 PM and 4:00 PM to control for the effects of circadian rhythms [30].

Cosa sta misurando lo studio?

Misure di risultato primarie

Misura del risultato
Lasso di tempo
1RM Squats and Bench Presses;Number of repetitions for 65% 1RM squats and bench presses
Lasso di tempo: 5 week
5 week

Collaboratori e investigatori

Qui è dove troverai le persone e le organizzazioni coinvolte in questo studio.

Sponsor

Studiare le date dei record

Queste date tengono traccia dell'avanzamento della registrazione dello studio e dell'invio dei risultati di sintesi a ClinicalTrials.gov. I record degli studi e i risultati riportati vengono esaminati dalla National Library of Medicine (NLM) per assicurarsi che soddisfino specifici standard di controllo della qualità prima di essere pubblicati sul sito Web pubblico.

Studia le date principali

Inizio studio (Stimato)

25 luglio 2026

Completamento primario (Stimato)

20 settembre 2026

Completamento dello studio (Stimato)

22 settembre 2026

Date di iscrizione allo studio

Primo inviato

17 luglio 2026

Primo inviato che soddisfa i criteri di controllo qualità

21 luglio 2026

Primo Inserito (Effettivo)

24 luglio 2026

Aggiornamenti dei record di studio

Ultimo aggiornamento pubblicato (Effettivo)

24 luglio 2026

Ultimo aggiornamento inviato che soddisfa i criteri QC

21 luglio 2026

Ultimo verificato

1 luglio 2026

Maggiori informazioni

Termini relativi a questo studio

Altri numeri di identificazione dello studio

  • TJUS2026-30

Piano per i dati dei singoli partecipanti (IPD)

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Descrizione del piano IPD

http://www.medresman.org.cn/login.aspx

Informazioni su farmaci e dispositivi, documenti di studio

Studia un prodotto farmaceutico regolamentato dalla FDA degli Stati Uniti

No

Studia un dispositivo regolamentato dalla FDA degli Stati Uniti

No

Queste informazioni sono state recuperate direttamente dal sito web clinicaltrials.gov senza alcuna modifica. In caso di richieste di modifica, rimozione o aggiornamento dei dettagli dello studio, contattare register@clinicaltrials.gov. Non appena verrà implementata una modifica su clinicaltrials.gov, questa verrà aggiornata automaticamente anche sul nostro sito web .

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