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

2026年7月23日 更新者：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.

研究概览

地位

尚未招聘

条件

干预/治疗

研究类型

介入性

注册 (估计的)

40

阶段

  • 不适用

联系人和位置

本节提供了进行研究的人员的详细联系信息，以及有关进行该研究的地点的信息。

学习联系方式

参与标准

研究人员寻找符合特定描述的人，称为资格标准。这些标准的一些例子是一个人的一般健康状况或先前的治疗。

资格标准

适合学习的年龄

  • 成人

接受健康志愿者

不

描述

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

学习计划

本节提供研究计划的详细信息，包括研究的设计方式和研究的衡量标准。

研究是如何设计的？

设计细节

  • 主要用途：治疗
  • 分配：随机化
  • 介入模型：顺序分配
  • 屏蔽：双倍的

武器和干预

参与者组/臂
干预/治疗
实验性的：控制
行为的：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].
实验性的：caf
行为的：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].
实验性的：VC
行为的：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].
实验性的：caf+VC
行为的：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].

研究衡量的是什么？

主要结果指标

结果测量
大体时间
1RM Squats and Bench Presses；Number of repetitions for 65% 1RM squats and bench presses
大体时间：5 week
5 week

合作者和调查者

在这里您可以找到参与这项研究的人员和组织。

赞助

Yunliang Zhang

研究记录日期

这些日期跟踪向 ClinicalTrials.gov 提交研究记录和摘要结果的进度。研究记录和报告的结果由国家医学图书馆 (NLM) 审查，以确保它们在发布到公共网站之前符合特定的质量控制标准。

研究主要日期

学习开始 (估计的)

2026年7月25日

初级完成 (估计的)

2026年9月20日

研究完成 (估计的)

2026年9月22日

研究注册日期

首次提交

2026年7月17日

首先提交符合 QC 标准的

2026年7月21日

首次发布 (实际的)

2026年7月24日

研究记录更新

最后更新发布 (实际的)

2026年7月27日

上次提交的符合 QC 标准的更新

2026年7月23日

最后验证

2026年7月1日

更多信息

与本研究相关的术语

关键字

其他相关的 MeSH 术语

其他研究编号

  • TJUS2026-30

计划个人参与者数据 (IPD)

计划共享个人参与者数据 (IPD)？

是的

IPD 计划说明

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

药物和器械信息、研究文件

研究美国 FDA 监管的药品

不

研究美国 FDA 监管的设备产品

不

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