An interventional study of Caffeine administration according to body mass (moderate intake- 7 mg/kg) and Placebo (Biotin Capsules) in Healthy, Young Adults and Athletic Performance, sponsored by Democritus University of Thrace. Completed at 1 site in Greece. Open to male participants aged 18 Years to 40 Years. Per ClinicalTrials.gov, last updated 2025-03-26.
Sponsored by Democritus University of Thrace · Not applicable, Interventional, and Other
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:
Participants had to:
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.
At the end of each round, the rating of perceived exertion (RPE) was recorded using the 6-to-20 Borg scale, and, one minute after the end of the workout, blood lactate concentration was measured again.
HR was monitored using a HR monitor (Polar H10) throughout the workout and averaged over each round.
Additionally, after completing the training sessions, the volunteers provided information about possible side effects (tachycardia, palpitations, feelings of anxiety/discomfort, headache, dizziness).
Democritus University of Thrace is the lead sponsor of 70 studies on the registry; 8 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
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)
Dietary Supplement: Caffeine administration according to body mass (moderate intake- 7 mg/kg)
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
Dietary Supplement: Placebo (Biotin Capsules)
This randomized, double-blind, crossover study aimed to investigate the acute effects of caffeine consumption on physiological responses and performance during a strength-focused CrossFit workout. Participants will consume either anhydrous caffeine (7.1 ± 0.7 mg/kg of body mass) or placebo, 60 minutes before a CrossFit workout aiming to perform as many repetitions as possible.
Consumption of biotin (BIOTIN tablets by Myprotein) at the same time as caffeine.
Performance During CrossFit® Workout
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.
Time frame: After 5, 10, 15 and 20 minutes of exercise
Rating of Perceived Exertion during the CrossFit program
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
Time frame: during the last 10 s of the 5th, 10th, 15th and 20th minute of exercise
Blood lactate concentration
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
Time frame: 1st measurement before the warm up and 2nd measurement one minute after the end of workout (i.e. after 20 min of exercise)
Heart Rate
Throughout the workout, heart rate was monitored using a heart rate monitor (Polar H10)
Time frame: 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
Maximum oxygen consumption was estimated using the 20-meter shuttle run test from the number of shuttles completed at exhaustion.
Time frame: baseline (during the 2nd visit)
Maximum heart rate measurement
Maximum Heart rate was determined during the 20-meter shuttle run test. Heart rate was continuously recorded using a heart rate monitor (Polar H10).
Time frame: Heart rate was continuously recorded during the test (every 1 s), until exhaustion. The highest heart rate at the time of exhaustion was recorded.
Plan to share: Yes — All IPD that underlie results in a publication
Supporting information: Study protocol, Sap, Icf
This study is completed, as verified in Mar 2025. You cannot join it, but the record below documents what was studied.
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Democritus University of Thrace