Effects of an Acute High Dose of Caffeine on Physiological Responses and Performance During a Strength-Focused CrossFit® Workout: a Randomized, Double - Blinded, Crossover Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 12
- 试验地点
- 1
- 主要终点
- Performance During CrossFit® Workout
研究概览
简要总结
The goal of this clinical trial was to investigate the effect of an acute dose of caffeine on CrossFit performance in young, healthy male CrossFit athletes. The main questions it aimed to answer were whether an acute dose of caffeine, compared to placebo:
- Can improve performance in a specific CrossFit workout
- Leads to a reduction in the Rating of Perceived Exertion
- Leads to an increase in blood lactate concentration at the end of the workout
Participants had to:
- Complete two sessions of a specific CrossFit training program (four rounds of five exercises, 50 seconds of exercise/10 seconds of rest), 60 minutes after consuming either anhydrous caffeine (7.1 ± 0.7 mg/kg of body mass) or an equivalent amount of placebo, aiming to perform as many repetitions as possible.
- Report subjective perception of fatigue using the Borg scale at the end of each round.
详细描述
Preliminary measurements The preliminary measurements included anthropometry, body composition estimation, dietary and habitual caffeine consumption assessment. To assess habitual caffeine consumption, the volunteers were asked to answer a questionnaire through an interview, which investigated the typical consumption of specific caffeine-containing foods and beverages over the past month. Additionally, medical history information was collected through personal interviews.
Main tests Aerobic fitness and maximum heart rate were assessed using the 20-meter shuttle run at an indoor gymnasium. For each main session, the volunteers arrived at the gym having followed specific preparation instructions. Specifically, they were instructed to avoid intense exercise for 24 hours before the test, be hydrated, eat a carbohydrate-rich meal 3-4 hours earlier, avoid alcohol for 24 hours before the test, and refrain from energy drinks, supplements, or caffeine on the test day.
The two main tests were conducted at the same time of day and under similar environmental conditions for each volunteer. After being weighed, the volunteers took either caffeine or biotin capsules, and, 40 minutes later, they began warming up so that the training session would start 60 minutes after taking the supplement. Before the warm-up, blood lactate concentration was measured using the Lactate Scout 4 automatic lactate analyzer.
The volunteers executed five exercises (50 seconds on, 10 seconds off) for four rounds, aiming to perform as many repetitions as possible with the correct technique. The five exercises were push-ups, power cleans, front squats, sit-ups, and deadlifts. The power clean, front squat, and deadlift were performed with an external load of approximately 40%, 50%, and 60% of body weight, respectively.
Performance was defined as the total number of repetitions per round (i.e. the sum of repetitions in all exercises per round), as well as the number of repetitions performed in each exercise per round.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Other
- 盲法
- Triple (Participant, Investigator, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 40 Years（Adult）
- 性别
- Male
- 接受健康志愿者
- 否
入选标准
- •Aged 18-40
- •At least 2 years of experience with CrossFit programs
- •Free of any medical condition that prevents the participant from performing the exercises of the training program at maximum capacity
排除标准
- •Consumption of caffeine and guarana supplements, unless were discontinued for at least two weeks before participating in the study
研究组 & 干预措施
Caffeine
Consumption of 7.1 ±0.7 mg/kg of body mass of anhydrous caffeine (Pure Caffeine tablets by Myprotein), 60 minutes before the start of the specific CrossFit training program (four rounds of five exercises, 50 seconds exercise/10 seconds rest)
干预措施: Caffeine administration according to body mass (moderate intake- 7 mg/kg) (Dietary Supplement)
Placebo
Consumption of biotin (BIOTIN tablets by Myprotein) as placebo, 60 minutes before the start of the specific CrossFit training program (four rounds of five exercises, 50 seconds exercise/10 seconds rest). The volunteers received the same number of capsules that they received in caffeine condition
干预措施: Placebo (Biotin Capsules) (Dietary Supplement)
结局指标
主要结局
Performance During CrossFit® Workout
时间窗: After 5, 10, 15 and 20 minutes of exercise
Performance was defined as the total number of repetitions completed by the volunteers in the CrossFit program, the repetitions of all exercises per round, and the repetitions of each specific exercise per round.
Rating of Perceived Exertion during the CrossFit program
时间窗: during the last 10 s of the 5th, 10th, 15th and 20th minute of exercise
Each partictipant had to record the subjective perception of fatigue, using the Borg scale (6 to 20, with higher score meaning feeling of higher exertion), at the end of each round of CrossFit program
Blood lactate concentration
时间窗: 1st measurement before the warm up and 2nd measurement one minute after the end of workout (i.e. after 20 min of exercise)
Blood lactate concentration was measured using the Lactate Scout 4 automatic lactate analyzer (EKF Diagnostics) in two time points: before the warm-up for CrossFit program and one minute after the end of the workout
次要结局
- Heart Rate(Heart rate was measured every 1 second of exercise. For analysis, heart rate was averaged over the following time ranges: 1-5 , 6-10 , 11-15 and 16-20 minutes of exercise)
- Aerobic fitness assessment(baseline (during the 2nd visit))
- Maximum heart rate measurement(Heart rate was continuously recorded during the test (every 1 s), until exhaustion. The highest heart rate at the time of exhaustion was recorded.)
研究者
ZOI KONIDARI
DIETICIAN-NUTRITIONIST
Democritus University of Thrace