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Study Title and Description

The effect of caffeine as an ergogenic aid in anaerobic exercise.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title The effect of caffeine as an ergogenic aid in anaerobic exercise.
Author K Woolf,WK Bidwell,AG Carlson,
Country
Year 2008
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? The primary purpose of this study was to examine the effects of a moderate dose of caffeine (5 mg/kg BW) on anaerobic exercise performance, hormonal responses (serum insulin and serum cortisol), exercise metabolites (serum free fatty acids [FFA], plasma lactate, and plasma glucose), physiological responses (BP and HR), and rating of perceived exertion (RPE) in highly trained male athletes. Our primary null hypothesis was that ingesting a shake with a 5 mg/kg BW dose of caffeine would not alter exercise performance (leg press, chest press, and 30-s Wingate test), hormonal responses, exercise metabolites, physiological responses, and RPE compared with a placebo in male athletes during anaerobic exercise.
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Participants: Participants were eligible if they were male, 18–40 years of age, and participated in >/=12 hr/week of programmed physical activity. They were currently participating in a comprehensive training program including strength, movement, and endurance activities for 2–4 hr/day. Participants reported to Athletes’ Performance on two occasions separated by 1 week for exercise testing. They fasted for 8–12 hr and abstained from caffeinated products for 48 hr. So that we could assess their historical caffeine intake, participants completed the Arizona Food Frequency Questionnaire (AFFQ; University of Arizona, Tucson, AZ; Martinez et al., 1999). Each provided a urine sample at baseline to detect caffeine. HR and BP were also monitored. An 8-hr fasting blood sample was taken by venipuncture to assess serum cortisol, serum insulin, serum FFA, plasma lactate, and plasma glucose concentrations. Immediately after the blood draw, participants consumed a commercial shake either with caffeine (caffeine, 5.0 mg/kg BW; carbohydrate [CHO], 0.125 g/kg BW) or without caffeine (placebo; CHO, 0.125 g/kg BW). A midpoint HR and BP were measured 30 min after the participants drank the shake. Sixty minutes after consuming the shake, participants performed three exercise tests with 60 s of rest between tests. This scenario is similar to how an athlete would use caffeine in competition or practice. Before the exercise tests, the participants completed a 10-min warm-up consisting of both dynamic and static stretches. The exercise tests consisted of a leg press, chest press, and 30-s Wingate test. The order of the leg press and chest press was determined at random; the Wingate test was always the final test. Participants completed the leg and chest press on Keiser exercise equipment (model A420, Fresno, CA), which uses pneumatic resistance during the extension phase. Participants were asked to push maximally with each repetition until they could no longer perform a full extension. The number of repetitions completed and total weight lifted (pounds × number of repetitions) were recorded after each test. Researchers measured HR and BP immediately after participants completed the Wingate test, and then a postexercise blood sample was drawn to assess for serum cortisol, serum insulin, serum FFA, plasma lactate, and plasma glucose concentrations. Participants also provided a postexercise urine sample to detect the presence of caffeine.
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How many outcome-specific endpoints are evaluated? 2
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Heart rate
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List additional health endpoints (separately). 2 Blood pressure (systolic and diastolic)
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List additional health endpoints (separately).3
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List additional health endpoints (separately).4
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Physiological
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? RCT
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description No information was provided.
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
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Measured or self reported? Measured
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Caffeine consumption vs. placebo. Each subjects eventually received either caffeine treatment or placebo treatment.
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) Paired t tests determined the independent effects of caffeine versus no caffeine on exercise performance during the bench press, leg press, and Wingate test. A repeated-measures analysis of variance (ANOVA) determined the independent effects of caffeine versus no caffeine on plasma glucose, serum insulin, serum FFA, plasma lactate, serum cortisol concentrations, and HR. Bonferroni’s post hoc test was used to determine differences between the preexercise, midpoint, and postexercise HR values. Wilcoxon’s signed rank test determined the independent effects of the treatment on RPE, as well as treatment and time effects on BP.
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What conflicts of interest were reported? Authors did not discuss this information.
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Refid 18708685
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What were the sources of funding? This research was supported by a grant from Experimental and Applied Science, Inc.
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Results & Comparisons

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