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Study Title and Description

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure.



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 Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure.
Author PJ O'Connor,RW Motl,SP Broglio,MR Ely,
Country
Year 2004
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 the research summarized here was to learn whether caffeine-induced reductions in naturally occurring muscle pain during exercise are dose dependent. The secondary purpose was to examine whether this type of hypoalgesia is strongly linked to increases in systolic blood pressure.
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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 (N = 12) were male nonsmoking college students of average body weight who reported low daily caffeine consumption (i.e. 100 mg/day) and no hypersensitivity to caffeine. The participants reported that they did not take any pain or antidepressant medication. Blood Pressure Blood pressure was measured in the right arm by manual auscultation. Pressures were measured simultaneously by two trained researchers using a mercury sphygmomanometer and binaural stethescope. If the two researchers recorded values that differed by > 4 mmHg then the values were discarded as inaccurate and the measurement was repeated 60 s later. Approximately 3% of the blood pressure measures were repeated because of differences between researchers. The inter-rater reliabilities of the measurements of diastolic and systolic blood pressure at rest and during exercise exceeded 0.95. Procedures Participants completed 1 day of preliminary testing and 3 days of experimental testing. The 3 days of experimental testing were separated by 1 week. Experimental testing was conducted in the morning (0700 h +/- 30 min). Before the experimental testing, participants were asked to abstain from (1) caffeine consumption for 1 week; (2) alcohol consumption for 24 h; and (3) eating and exercising for 12 h. Experimental Days On the experimental days, two of the researchers simultaneously recorded the participant’s blood pressure and heart rate. The participant subsequently ingested capsules that contained one of two doses of caffeine (5 or 10 mg/kg body weight) or placebo with, 500 ml of water. After consuming the capsule the participants sat and read quietly in a sound-dampened, thermoneutral environmental chamber maintained at 23 +/-2oC and 50% relative humidity. One hour after ingesting the capsules, two of the researchers again recorded the participant’s blood pressure and heart rate. The participant then walked to another room and performed 30 min of cycling on an ergometer at an intensity of 60% VO2 peak. The participant’s perception of leg muscle pain intensity, as well as blood pressure, work rate, and heart rate were recorded every 5 min during the submaximal exercise bouts. Drug Delivery and Content The two doses of caffeine (Caffeine Anhydrous, USP/NF, Gallipot, St Paul, MN) and the placebo were delivered in gelatin capsules (No. 1, Eli Lilly and Company, Indianapolis, IN). The dose of placebo was an equal number of gelatin capsules containing white, all purpose flour. Caffeine was administered using a double-blind procedure to protect against possible subject and experimenter expectancy effects. We recognize that subjects likely experienced some side effects after caffeine consumption, but we are unaware of another experimental design for better controlling subject and experimenter expectancy effects. The order of drug administration was counter-balanced. Data Analysis Descriptive statistics for the 12 participants are presented in text and tables as mean +/- SD and in figures as mean +/- SEM. The systolic and diastolic blood pressure and heart rate data recorded before and 60 min after caffeine or placebo administration were analyzed with 3 (Drug: 10 mg/kg body weight caffeine, 5 mg/kg body weight caffeine, and placebo) x 2 (Time 0 and 60 min) repeated measures ANOVAs based on the univariate F-statistic. The systolic and diastolic blood pressure and heart rate data recorded during exercise were analyzed with 3 (Drug: 10 mg/kg body weight caffeine, 5 mg/kg body weight caffeine, and placebo) x 6 (Time: 5, 10, 15, 20, 25, and 30 min) repeated measures ANOVAs based on the univariate F-statistic. The family-wise error rate was controlled using the Bonferroni adjustment when tests of simple effects were conducted.
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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) Blood pressure (SBP and DBP)
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List additional health endpoints (separately). 2 Heart rate
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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 Blood pressure was measured in the right arm by manual auscultation. Pressures were measured simultaneously by two trained researchers using a mercury sphygmomanometer and binaural stethescope.
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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.) Subjects served as their own controls (placebo)
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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) None
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What conflicts of interest were reported? No information provided
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Refid 15157690
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What were the sources of funding? No information provided
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