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Study Title and Description

Effect of caffeine ingestion on one-repetition maximum muscular strength.



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 Effect of caffeine ingestion on one-repetition maximum muscular strength.
Author TA Astorino,RL Rohmann,K Firth,
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)? Regarding cardiovascular effects, the objective to evaluate the acute effects of caffeine (6 mg/kg) on heart rate and blood pressure compared to placebo used a double-blind crossover design among individuals who were familiar with resistance training. The authors evaluated the effects using one-repetition maximum performance.
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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: 22 resistant-trained men were involved in the study. Four men had never been exposed to caffeine. Study Design: Subjects were randomly assigned to treatment (6 mg/kg caffeine or placebo) 1-hour pre-exercise in a double-blind crossover design was used. Trials were separated by 1 week. Monitoring of exercise status and dietary intake: Participants completed a 24-hour diet and exercise recall before each trial. They were given a list of caffeine-containing items and over-the-counter medicines show they would refrain from caffeine intake for 48-hours pre-visit. Treatment: Anhydrous pharmaceutical-grade caffeine (CAF) or a placebo (PL) consisting of dimethyl cellulose was provided to subjects in capsules to ingest 1 hour pre-exercise. Subjects ingested 6 mg/kg caffeine. One week later, subjects ingested the placebo treatment and repeated the identical exercise protocol. Pretest measurements: Heart rate was measured with telemetry and blood pressure was measured by manual sphygmomanometry. Exercise protocol: Participants initially warmed-up on a stationary bike for 5 min. Pre-exercise heart rate and blood pressure were recorded 4 minutes into the warm-up. Participants then completed a warm-up set on the standard barbell bench press of 12–15 repetitions at a load of 43–61 kg. Determination of 1-RM (one-repetition maximum) was conducted based on the methods of Baechle and Earle (2000). 1-RM represented the maximum weight lifted once with proper form. Two minutes of rest was allotted between sets, and 1-RM was determined in 3–6 sets. Participants were given verbal encouragement throughout the protocol. After 1-RM determination, 60% of 1-RM was placed on the bar, and participants completed repetitions to failure, which was used as an index of muscular endurance. Total weight lifted (in kg) was calculated as repetitions ·x weight. Total weight lifted (in kg) was calculated as repetitions ·x weight. HR, BP, and rating of perceived exertion (RPE) were recorded within 5 seconds of the last repetition. Subjects returned 1 week later and repeated the identical protocol after ingestion of the other treatment. After trial 2, they filled out a side effects/symptoms inventory that contained questions regarding their health status, and they were asked if they could identify the caffeine trial.
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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 Systolic blood pressure
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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 Heart rate was measured with telemetry and blood pressure was measured by manual sphygmomanometry.
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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.) In this randomized cross-over trial, each person served as their own placebo (capsule containing dimethyl cellulose).
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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) As reported by authors, ANOVA was used to examine differences in all indices of muscular strength and endurance and RPE between caffeine and placebo. A 2 (treatment) · 2 (time, signifying pre-exercise and during the warm-up) analysis of variance with repeated measures was used to examine differences in cardiovascular variables (heart rate and systolic blood pressure) between the caffeine and placebo treatment.
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What conflicts of interest were reported? None were mentioned.
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Refid 17851681
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What were the sources of funding? None were mentioned.
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