The Effects of Caffeine and Vitamin C on Maximum Strength and Strength Endurance in Adolescents With Mild Mental Fatigue
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.
Studieoversigt
Status
Betingelser
Intervention / Behandling
Undersøgelsestype
Tilmelding (Anslået)
Fase
- Ikke anvendelig
Kontakter og lokationer
Studiekontakt
- Navn: Zhizheng REN
- Telefonnummer: +8619862079078
- E-mail: 19862079078@163.com
Deltagelseskriterier
Berettigelseskriterier
Aldre berettiget til at studere
- Voksen
Tager imod sunde frivillige
Beskrivelse
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.
Studieplan
Hvordan er undersøgelsen tilrettelagt?
Design detaljer
- Primært formål: Behandling
- Tildeling: Randomiseret
- Interventionel model: Sekventiel tildeling
- Maskning: Dobbelt
Våben og indgreb
Deltagergruppe / Arm |
Intervention / Behandling |
|---|---|
|
Eksperimentel: Styring
|
Adfærdsmæssigt: 1RM squats and bench presses; repetitions at 65% of 1RM for squats and bench presses
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].
|
|
Eksperimentel: caf
|
Adfærdsmæssigt: 1RM squats and bench presses; repetitions at 65% of 1RM for squats and bench presses
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].
|
|
Eksperimentel: VC
|
Adfærdsmæssigt: 1RM squats and bench presses; repetitions at 65% of 1RM for squats and bench presses
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].
|
|
Eksperimentel: caf+VC
|
Adfærdsmæssigt: 1RM squats and bench presses; repetitions at 65% of 1RM for squats and bench presses
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].
|
Hvad måler undersøgelsen?
Primære resultatmål
Resultatmål |
Tidsramme |
|---|---|
|
1RM Squats and Bench Presses；Number of repetitions for 65% 1RM squats and bench presses
Tidsramme: 5 week
|
5 week
|
Samarbejdspartnere og efterforskere
Sponsor
Datoer for undersøgelser
Studer store datoer
Studiestart (Anslået)
Primær færdiggørelse (Anslået)
Studieafslutning (Anslået)
Datoer for studieregistrering
Først indsendt
Først indsendt, der opfyldte QC-kriterier
Først opslået (Faktiske)
Opdateringer af undersøgelsesjournaler
Sidste opdatering sendt (Faktiske)
Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier
Sidst verificeret
Mere information
Begreber relateret til denne undersøgelse
Yderligere relevante MeSH-vilkår
Andre undersøgelses-id-numre
- TJUS2026-30
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