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Study Title and Description

Acute effects of caffeine on heart rate variability in habitual caffeine consumers.



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 Acute effects of caffeine on heart rate variability in habitual caffeine consumers.
Author R Rauh,M Burkert,M Siepmann,M Mueck-Weymann,
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)? The aim of the study was to detect the acute effects of caffeine on young and healthy habitual caffeine consumers
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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) 30 male subjects (age 25.2 ± 3.1 years, height 182.5 ± 6.5 cm, weight 76.8 ± 9.2 kg, mean ± SD) were enrolled in the study. The subjects were included after a standard physical examination. All were healthy without taking any medication. All were habitual coffee drinkers, 22 of them more than one dose per day. The study was carried out under randomized double-blinded and crossover conditions. Each subject orally received capsules with 100 or 200 mg caffeine or placebo at three different days. An interval of 48 h was kept between the separate measurements. Subjects were asked not to smoke nor drink coffee, tea or alcoholic beverages 10 h before and during the examination. On the day of experiment, standard electrocardiogram (ECG) and respiration (strain gauge belt) were recorded for 6 min as a baseline with subjects sitting comfortably in an armchair. Signals were digitized and recorded with a PowerLab 410 device (ADInstruments Inc., Bella Vista, NSW, Australia). During the first 3 min, the subjects were listening to relaxing music. Then they were instructed to metronomic breathing with a rate of 6/min (0.1 Hz). Thereafter, the capsule with either caffeine 100 or 200 mg or placebo was applied and whole the procedure was repeated 30, 60 and 90 min after intake. Additionally, before each measurement blood pressure was determined. Data was analysed with the HRV extension of Chart 3.6 (ADInstruments Inc.). As time domain parameters of HRV, we appraised the root mean square of successive differences (RMSSD), the standard deviation of all NN intervals (SDNN) and the percentage of successive NN intervals differing >50 ms (pNN50). As frequency domain parameters, we calculated the low frequency power (LF, 0.04–0.15), the high frequency power (HF, 0.15–0.4 Hz) and the ratio LF/HF. Additionally, mean heart rate (HR) was determined. Parameters were acquired at resting conditions (first 3 min) and at metronomic breathing (second 3 min period). Data was tested on Gaussian distribution with the Kolmogoroff–Smirnov test. As nearly all parameters are not normally distributed, values are presented as median with lower (Q1) and upper (Q3) quartile. Results were compared at the same time point (0, 30, 60 and 90 min) using the Friedman test. If significant differences were found, Wilcoxon test was performed. Significance was accepted for P<0.05.
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How many outcome-specific endpoints are evaluated? 3
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3 Heart rate variability (root mean square of successive differences [RMSSD], standard deviation of all NN intervals [SDNN], percentage of successive NN intervals differing >50 ms [pNN50], low frequency power [LF], high frequency power [H], ratio LF/HF)
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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 Standard electrocardiogram (ECG) signals were digitized and recorded with a PowerLab 410 device (ADInstruments Inc., Bella Vista, NSW, Australia).
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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
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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 16640511
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.