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Study Title and Description

Effects of different doses of caffeine on exercise responses in young children.



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 different doses of caffeine on exercise responses in young children.
Author KR Turley,JR Bland,WJ Evans,
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)? This study investigated the effects of three different doses of caffeine on physiological responses to exercise in young children.
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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: Forty healthy, prepubertal 7- to 9-yr-old children (20 girls and 20 boys) voluntarily participated in this study. All subjects were free from disease (verified by questionnaire completed by parent/guardian), with BP below the 95th percentile relative to their stature, sex, and age, with a body mass index (BMI) of less than 30. Activity questionnaires confirmed that all subjects were active but not involved in organized sport or formal training. Also, children` s caffeine intake was assessed via questionnaire completed by the parents. Study design: Each subject visited the laboratory five times. Consents, child assents, and questionnaires were completed, and skinfolds were measured for body composition determination during visit 1. Each visit began with the measurement of stature and mass followed by preexercise BP and HR. Also on visit 1, following preexercise measures, an incremental exercise test to exhaustion was performed to determine peak oxygen consumption (VO2peak). On visits 2–5, following preexercise measures, one of four treatment trials was randomly performed in a double blind, counterbalanced design. Treatment trials were as follows: 0 mg of caffeine per kilogram of body mass (placebo), 1 mg of caffeine per kilogram of body mass, 3 mg of caffeine per kilogram of body mass, and 5 mg of caffeine per kilogram of body mass. Treatment trials: Treatment trials began 1 h prior to exercise testing, when subjects consumed the treatment drink. During the 1-h wash-in period, subjects either resumed normal school day activity or sat in the lab watching movies and playing computers. At 60 min after consumption, stature, mass, and preexercise measures were taken. Subjects then rode the cycle ergometer for two consecutive 8-min stages at 25 W and then 60% VO2peak. During this time BP was obtained every 2 min while HR and VO2 were monitored continuously. Treatment trials were conducted at least 48 h apart and within a 2- to 3-wk time period. Each test was conducted within 1–2 h of the same time of day to control for diurnal variation The treatment: The placebo drink consisted of 118 mL of Sprite, 74 mL of cherry syrup, and 30 mL of water. The caffeine treatments consisted of the placebo with either 1 mg/kg body mass, 3 mg/kg body mass, or 5 mg/kg body mass of anhydrous caffeine dissolved in solution. Taste tests conducted during earlier studies confirmed that subjects could not differentiate between the treatments and placebo. Measurements: Caffeine intake was estimated with a standard 3-d dietary recall (two weekdays and one weekend day) completed by a parent/guardian of each child. A semiautomated BP-measurement device (Colin model STBP-780, Colin Medical Instruments, San Antonio, TX) was used to measure BP from the right arm of each subject during preexercise and exercise. Upper-arm circumference at midbicep was measured to ensure that the BP cuff bladder width was about 40% of the subject’s arm circumference. During preexercise, three to four BP measures were then taken 2–3 min apart while seated in a desk with the arm at heart level during a 5- to 10-min time period. Preexercise HR was measured using a Polar HR monitor (Polar Vantage XL, Stamford, CT). Preexercise values for each test was the average of the lowest four consecutive 5-s values within the 5–10 min preceding the start of exercise. Exercise BP was measured every 2 min, and the average BP for the last 2 min of each exercise intensity was used in the analysis. The average of the last four consecutive 5-s HR values for the last 2 min of each exercise stage was 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) Blood pressure (SPB 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
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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? 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 (received 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) Physical characteristic differences between boys and girls were assessed by a one-way ANOVA. To compare the effects of caffeine versus placebo in children, a 2 (boys and girls) x 4 (placebo, 1, 3, and 5 mg/kg caffeine) x 3 (preexercise, 25 W, and 60% VO2peak) three-way repeated-measures ANOVA with multiple comparisons using the Bonferroni post hoc adjustment was run. There were no significant gender x treatment interactions, and so the boys` and girls` data were combined.
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What conflicts of interest were reported? Conflicts of interest were not discussed.
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Refid 18408611
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What were the sources of funding? Arkansas INBRE, a grant from the NIH, and the National Center for Research Resources.
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Results & Comparisons

No Results found.