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Study Title and Description

The effects of different doses of caffeine on endurance cycling time trial performance.



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 effects of different doses of caffeine on endurance cycling time trial performance.
Author B Desbrow,C Biddulph,B Devlin,GD Grant,S Anoopkumar-Dukie,MD Leveritt,
Country
Year 2012
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)? Thus the purpose of this investigation was to determine the effects of two clearly contrasting pre-exercise bolus doses of caffeine on the performance of a 1 hr cycle time trial in well-trained and fed athletes.
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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 asked to abstain from all dietary sources of caffeine, alcohol and strenuous exercise for the 24 hr preceding each experimental trial. Experimental trials: Each participant completed three time trials, in random order, under double-blind conditions. At 90 min prior to the trials, participants ingested four opaque capsules containing either pure anhydrous caffeine (equivalent to 3 mg/kg body mass of caffeine (low dose caffeine) or 6 mg/kg body mass of caffeine (high dose caffeine) or the placebo treatment containing approximately 400 mg of Metamucil (100% psyllium husk fibre). After resting in a thermo-neutral environment, each participant performed a standardized warm-up and immediately prior to the commencement of the time trial, another venous blood sample (5 ml) was collected. Subjective ratings of perceived exertion (RPE) (Borg, 1982) and heart-rate (HR) values (Polar Electro, Kempele, Finland) were recorded at each 10% of the time trial.
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How many outcome-specific endpoints are evaluated? 1
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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
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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 Subjective ratings of perceived exertion (RPE) (Borg, 1982) and heart-rate (HR) values (Polar Electro, Kempele, Finland) were recorded at each 10% of the time trial.
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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.) Placebo group.
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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) Statistically significant differences were accepted at the 5% level. All dependent measures were analysed using repeated measures ANOVA exploring dose and time interactions. Where significant main effects were observed pair-wise (Bonferroni) comparisons were conducted to identify the specific nature of the differences. In addition, inferential statistics based on 95% confidence limits, were used to assess the clinical utility and practical applicability of results (Hopkins, 2000). The magnitude of the smallest worthwhile change in time trial performance was assumed to be an improvement/decrement in time to complete the set amount of work by4 1% (when trials performed under conditions of caffeine treatment are compared to those performed under placebo conditions), based on the coefficient of variation (CV) derived from Laursen, Shing and, Jenkins (2003) using familiarised participants. The magnitude of the effect of caffeine was expressed using Cohen-type effect sizes and interpreted using a modified, performance-based scale (Hopkins, 2000).
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What conflicts of interest were reported? Not discussed.
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Refid 22142020
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What were the sources of funding? Not discussed.
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Results & Comparisons

No Results found.