RecruitingACTRN12621001394831

Individual and additive effects of blackcurrant juice and caffeine intake on high-intensity intermittent exercise performance in physically active healthy male volunteers

Sponsor

Massey University

Enrollment

15 participants

Start Date

Aug 16, 2021

Study Type

Interventional

Conditions

Exercise performance

Summary

Blackcurrant contains high levels of anthocyanins which have been shown to manage oxidative stress and inflammation, reduce cell damage, improve immunity, and enhance blood flow. Exercise performance improves with blackcurrant supplementation in a variety of settings including running/sprinting, intermittent exercise, and rock climbing. Caffeine is one of the most widely used psychoactive drugs in the world due to its accessibility, evidenced ergogenic effects, and few negative side effects. Both blackcurrant and caffeine seem to afford greater benefits to athletes when they are in a fatigued state; therefore, it would be reasonable to assume that adding caffeine to a blackcurrant juice will provide greater performance benefit. Therefore, we aim to examine the effect of caffeine and blackcurrant ingestion, provided before exercise to 15 previously physically fatigued male athletes, on various performance and metabolic parameters during a well-established exercise test (The LIST). Athletes will come to the lab for four main trials, with each trial taking place over two days: an initial fatiguing cycle exercise will be performed on day 1, followed by a running performance test on day 2. Participants will consume different quantities of caffeine, blackcurrant juice, placebo in each trial.

Eligibility

Sex: MalesMin Age: 18 YearssMax Age: 45 Yearss

Plain Language Summary

Simplified for easier understanding

Athletes frequently use caffeine to improve performance, and blackcurrant juice — rich in natural compounds called anthocyanins — has also been shown to boost exercise performance and reduce fatigue. This study investigates whether combining both caffeine and blackcurrant juice provides even greater performance benefits than either alone during high-intensity intermittent exercise. Male athletes aged 18–45 will complete four exercise trials, each across two days: a hard cycling session on day one to cause fatigue, followed by a standardised running performance test on day two. In each trial, participants consume either caffeine, blackcurrant juice, both together, or a placebo. Various performance and metabolic measurements will be taken throughout. You may be eligible if you are a healthy, well-trained male aged 18–45, a non-smoker, and can sustain 90 minutes of moderate cycling and high-intensity intermittent running. You must have no known reaction to blackcurrants or caffeine, and not be a very heavy caffeine user or completely caffeine-naive. Those with a BMI over 30 or a history of diabetes, cardiovascular disease, or hypertension are excluded.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

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Interventions

The 2Before study is a controlled, double-blind, crossover intervention trial in physically active healthy males (18-45 years), designed to examine the effect of caffeine and blackcurrant ingestion, provided before exercise to 15 previously physically fatigued male athletes, on various performance and metabolic parameters during a well-established running performance test (the Loughborough intermittent shuttle test - LIST). Athletes will come to the lab for four main trials, with each trial taking place over two days: an initial fatiguing cycle exercise will be performed on day 1, followed by a running performance test on day 2. The fatiguing cycle exercise involves cycling at 30 min at 70% VO2max along with 3 x 50-s 'sprints' at double the resistive load (2 min rest in between each sprint) that is followed by 45 min at VO2max with a rated perceived exertion of 12-13 (20-point scale) (total duration approx. 85 minutes). Participants will perform the exercise 1 hour after the drink administration. For the LIST, the participants undertake shuttle running for 6 x 15-minutes (total duration 90 minutes) blocks of exercise at approx. 70%VO2max intensity. The running patterns are designed to mimic intermittent sport exercises (e.g., soccer, hockey) and include walking, sprinting, jogging, and running. The participants will also receive additional 5 x 3-minute rest periods interspersed within the exercise protocol, and the exercise will commence 1 hour after the drink administration. The four main trials will explore four different conditions - Arm 1: Blackcurrant juice on day 1, and blackcurrant juice on day 2 (no caffeine) [blackcurrant, blackcurrant]; Arm 2: Placebo drink on day 1, and placebo drink containing 240mg caffeine on day 2 [placebo, caffeine]; Arm 3: Blackcurrant juice on day 1, and blackcurrant juice containing 240mg caffeine on day 2 [blackcurrant, blackcurrant + caffeine]; and Arm 4: Arm 2: Placebo drink on day 1, and placebo drink with no caffeine on day 2 [placebo, placebo]. The blackcurrant juice consists of blackcurrant juice concentrate (11g of blackcurrant powder containing 146 mg of anthocyanins), maltodextrin, monk fruit extract, and natural flavors. The blackcurrant juice concentrate will be mixed with water to form a solution of 75 ml, and it will then be given to the participant via drink bottles under staff supervision on day 1. Natural caffeine will be administered in the dose of 240 mg, and it will be mixed with blackcurrant juice on day 2 of the main trial under staff supervision. Participants will cycle (Day 1) and perform the LIST (day 2) in the presence of exercise scientists or the lab manager. Trained phlebotomists will take blood samples through cannulation (cycling) and venepuncture (LIST) during the trials. Research assistants trained in first aid will also be present at all times to supervise all activities during the familiarization and main trials. The washout period between trials will be at least 7 days.

Locations(1)

Auckland, New Zealand

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ACTRN12621001394831