Individual and additive effects of blackcurrant juice and caffeine intake on high-intensity intermittent exercise performance in physically active healthy male volunteers
Massey University
15 participants
Aug 16, 2021
Interventional
Conditions
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
Inclusion Criteria1
- Participants must be proficient in English and must be males between the ages of 18-45 years old. They should be well trained and be able to cycle at a moderate intensity for 90 min and also complete 90 min of high-intensity intermittent running (The LIST). They must be non-smokers and must pass health screening to perform the exercise. They should not be very heavy users of caffeine (>6mg/ kg/day) (barista coffee approx. 11.5mg/70kg) nor should be nonusers/caffeine naïve. Lastly, participants must have no known history of an adverse reaction to blackcurrant and/or other berry food products.
Exclusion Criteria1
- individuals with a BMI of 30 kg/m2 and above or with a history of diabetes, cardiovascular disease, or hypertension will be excluded from the trial. Additionally, individuals with a known adverse reaction to caffeine and blackcurrant will also be excluded.
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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)
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ACTRN12621001394831