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Study Title and Description

Effects of caffeine on physiological responses to exercise in young boys and girls.



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 in young boys and girls.
Author KR Turley,JW Gerst,
Country
Year 2006
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 was designed to investigate the acute effects of caffeine on cardiovascular, metabolic, and respiratory responses during aerobic exercise in young children, to determine the reliability of these responses, and to determine whether differences in these effects exist between boys and girls.
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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 Fifty-two healthy 7- to 9-yr-old children (26 girls and 26 boys) volunteered to participate in this study. To be included in the study, the parents filled out an activity questionnaire to ensure that the children were active but not involved in formal training or organized sports. Although pubertal status was not assessed, parents of the children answered a series of questions regarding pubertal status to ensure that there were no overt signs of pubertal development (e.g., pubertal hair). All children were considered prepubertal based on this information. Study Design Each child visited the laboratory six times. During visit 1, consents, assents, and questionnaires were completed and skinfolds were measured for body composition determination. Each visit began with the measurement of height and weight followed by resting (pre-exercise) BP and HR. On visits 1 and 2, following resting measures, an incremental exercise test to exhaustion was performed to determine maximal oxygen consumption (VO2max ). On visits 3–6, following resting measures, one of two placebo trials or one of two caffeine trials was randomly and blindly conducted. To blind the study, one laboratory assistant’s sole responsibility was to randomize and code the trials and mix the drinks. Further, the code was not revealed to the other investigators until all testing of a given subject was complete. Treatment Trials Treatment trials began 1 h prior to exercise testing when laboratory personnel delivered a drink to the children’s school or home. After the children consumed the drink, they resumed normal daily activity. The children then came to the laboratory 1 h after consuming the drink. Upon arrival, height, weight, and resting measures (BP and HR) were obtained. Following resting measures, the children rode the cycle ergometer for two consecutive 8-min periods each, at 25 and then 50 W. During this time, HR was monitored continuously while BP was obtained every 2 min. Each treatment trial was conducted at least 24 h apart and within a 2- to 3-wk time period. To control for diurnal variation, each test was conducted within 1–2 h of the same time of day. Prior to each test, both the children and their parents were informed that there was to be no caffeine consumption on the day of the test, no exercise was to be performed, diet was to be as similar as possible on the day of each test, and the children were to obtain a normal night’s rest. This was verbally verified prior to each test. Treatment The placebo drink (PL) consisted of 118 mL of Sprite, 74 mL of cherry syrup, and 30 mL of water. The caffeine drink (CAF) consisted of the placebo with 5 mg/kg body mass of anhydrous caffeine dissolved in the same solution. During pilot testing, taste tests were conducted to ensure that the subjects could not differentiate between the treatment and placebo drink. Measurements Both resting and exercise BP were measured on the right arm with a semiautomated BP measurement device (Colin model STBP-780, Colin Medical Instruments, San Antonio, TX). Three to four resting (pre-exercise) BP measures were then taken 2–3 min apart in the seated position on the cycle ergometer over a 5- to 10-min period. Resting HR was measured using a Polar HR monitor (Polar Vantage XL, Stamford, CT). Resting values for each test were the average of the lowest four consecutive 5-s values within the minute preceding the start of exercise. Exercise BP was measured every 2 min. The average BP for the last 2 min of each exercise intensity was used. The average of the last four consecutive 5-s HR values for minutes 7 and 8 were averaged for each exercise intensity. Analysis Trial 1 and 2 values for both CAF and PL were averaged and used in the statistical analysis. To compare sex differences and CAF versus PL a 2 x 2 (gender by drink), repeated-measures ANOVA was used at rest and each exercise intensity using PROC MIXED in SAS. Data are represented as mean +/- SD. Significance is reported at the P < 0.05 level unless stated otherwise.
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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, 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 Both resting and exercise BP were measured on the right arm with a semiautomated BP measurement device (Colin model STBP-780, Colin Medical Instruments, San Antonio, TX). Resting HR was measured using a Polar HR monitor (Polar Vantage XL, Stamford, CT).
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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.) Subject serves 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 16540840
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.