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Study Title and Description

Effects of caffeine on physiological responses to exercise: boys versus men.



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 Effects of caffeine on physiological responses to exercise: boys versus men.
Author KR Turley,T Desisso,JW Gerst,
Country
Year 2007
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)? To compare the influence of caffeine on physiological responses to exercise between boys and men.
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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) Subjects: Twenty-six healthy 7- to 9-year-old boys and 26 healthy 18- to 29-year-old males voluntarily participated in this study. Study design: Six laboratory visits were required of all participants. Consents, assents, and questionnaires were completed and skinfolds were measured for body composition determination during the first visit. Each visit began with the measurement of height and weight followed by pre-exercise BP and HR. On Visits 1 and 2, following resting measures, an incremental exercise test to exhaustion was performed to determine peak oxygen consumption. After pre-exercise measures on Visits 3–6, one of two placebo trials or one of two caffeine trials was randomly conducted. Treatment trials: One hour before exercise testing laboratory personnel delivered a drink to the participants. Once participants arrived at the laboratory, pre-exercise BP and HR were measured. Participants then rode the cycle ergometer for two consecutive 8-min stages at 25W and then 50W in children, and 50 W and then 60% VO2 peak in adults. The 60% VO2 peak work rate in adults was chosen because the 50 W work rate in boys was equal to ~60% of their VO2 peak. During exercise testing BP was measured every 2 min and VO2 and HR were monitored continuously. Treatment trials were conducted within a 2–3 week time period and at least 24 hr apart. To control for intra-participant diurnal variation, each test was conducted within 1–2 hr of the same time of day for each participant. During Visit 1 and before each test the children, their parents, and adult participants were informed that there was to be no caffeine consumption, no exercise, and diet was to be as similar as possible the day of each test, and a normal night’s rest was to be obtained the previous night. Treatment: For children, the placebo drink consisted of 118 ml of Sprite, 74 ml of cherry syrup, and 30 ml of water. The adult placebo consisted of 105 ml of Sprite, 150 ml of cherry syrup, and 45 ml of water. The caffeine drink consisted of the placebo with 5 mg/kg body mass of anhydrous caffeine dissolved in solution. An intermediate dose of 5 mg/kg body mass was used with values ranging from 1.6–10 mg/kg reported in children’s literature, and 3–13 mg/kg body mass reported in adult literature. Both adult and child taste tests were conducted during pilot testing to ensure that the participants could not differentiate between the placebo and treatment drinks. Measurements: Blood pressure was measured on the right arm with a semiautomated BP-measurement device (Colin model STBP-780, Colin Medical Instruments, San Antonio, TX). The participant’s upper arm circumference was measured at mid-bicep (25) to ensure that the appropriate cuff size was used. Three to four pre-exercise BP measures were taken in the seated position on the cycle ergometer 2–3 min apart over a ~10 min time period. Polar heart rate monitors (Polar Vantage XL, Stamford, CT) were used to measure HR. Pre-exercise HR values were the average of the lowest four consecutive 5-s values within the minute preceding the start of exercise. Exercise BP was obtained every 2 min (see Figure 1), with the average BP for the last 2 min of each exercise intensity used in analysis. The average of the last four consecutive 5-s HR values for Minute 7 and 8 were averaged for each exercise intensity.
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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 Blood pressure was measured on the right arm with a semiautomated BP-measurement device (Colin model STBP-780, Colin Medical Instruments, San Antonio, TX). The participant’s upper arm circumference was measured at mid-bicep (25) to ensure that the appropriate cuff size was used. Three to four pre-exercise BP measures were taken in the seated position on the cycle ergometer 2–3 min apart over a ~10 min time period. Polar heart rate monitors (Polar Vantage XL, Stamford, CT) were used to measure HR.
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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, Children
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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.
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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) Subjects could not be involved in organized sports or formal training. Younger subjects had to be pre-pubertal to be included in the study.
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What conflicts of interest were reported? None were mentioned.
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Refid 18089905
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What were the sources of funding? None were mentioned.
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Results & Comparisons

No Results found.