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Study Title and Description

Ergogenic effects of caffeine on simulated time-trial performance are independent of fitness level



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 Ergogenic effects of caffeine on simulated time-trial performance are independent of fitness level
Author T. A. Astorino, T. Cottrell, A. T. Lozano, K. Aburto-Pratt and J. Duhon
Country
Year 2011
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 primary aim of this study was to compare the magnitude of caffeine’s ergogenic effects on cycling performance in trained as well as recreationally active individuals.
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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) Participants Two groups of eight healthy, active men who completed a minimum of 5 hours/week of exercise for the preceding 2 years participated in the study. The trained group was composed of athletes competing in sports including cycling, running, or triathlon, while persons in the active group regularly participated in team sports, resistance training, and/or cardiovascular exercise. There were no differences (p >0.05) in age, height, mass, body fat, physical activity, and caffeine across groups; however, VO2max and maximal workload were significantly different (p<0.05). All participants habitually ingested caffeine 2–7 days/week, although none was a heavy caffeine user (>350mg/day). They filled out a health-history questionnaire to ensure they met all inclusion criteria and were free of known disease. Design Participants were instructed to come to the lab in a well-rested and hydrated state. They visited the laboratory on five occasions at the same time of day within subjects. Prior to each visit, they refrained from intense lower-body exercise for 48 hours and were 3 hours postabsorptive (fasted). Familiarization testing was completed on days 1 and 2, followed by completion of a 10 km cycling time trial on days 3–5. One hour prior to exercise, they ingested 5 mg/kg caffeine or placebo. A single-blind, crossover design was used, and treatment order was assigned using a Latin Squares design. Familiarization Testing On day 1, participants completed ramp exercise to volitional fatigue on an electrically braked cycle ergometer (Velotron DynaFit Pro; RacerMate, Seattle, WA) to assess VO2max. They warmed up for 2 minutes at intensities between 50 and 80W/min, and subsequently power output was increased by 25–40W/min. During exercise, gas exchange data were obtained every 15 seconds using a metabolic cart (ParvoMedics True One, Sandy, UT), and heart rate (HR) was continuously assessed via telemetry (Polar Electro, Lake Success, NY). After this bout, participants cooled down for 5 minutes at 50W, then rested for 10 minutes, during which water intake was allowed ad libitum. They warmed up for 5 minutes at 50W, and then were familiarized with a 10km self-paced time trial (Central Park course; Velotron RacerMate 3-D Software, Seattle, WA) characterized by periods of hill inclines, downhill cycling, and flat terrain during which they were instructed to complete the course as fast as possible, and told that selecting a higher gear allowed them to pedal faster. During exercise, they were continuously provided with strong verbal encouragement and were allowed to drink water ad libitum. The only feedback provided during the trial was their cadence, gearing, and progress on the course, which were revealed on the computer screen. HR, cycling time, and rating of perceived exertion (RPE) were assessed every 1.6km as well as at exercise cessation. They returned 48 hours later at the same time of day and repeated this time trial after a 5-minute warm-up at each of 50 and 100W. Experimental Protocol For the next three visits separated by at least 48 hours, participants completed the 10km time trial after completion of the standard 10-minute warm-up. Pretrial, they were refamiliarized with the RPE scale, reminded to go ‘‘all-out’’ during the trial, and were asked whether they experienced any symptoms of drink ingestion, which were denoted. RPE, HR, and cycling time were recorded every 1.6 km. After the last trial, participants were asked whether they could identify any differences between trials. Treatment Ingestion Solutions ingested over the 3 days of testing included two boluses of anhydrous caffeine (Gallipot, St. Paul, MN) (5 mg/kg body weight) (C1 and C2) or placebo. All doses were weighed to the nearest 0.001 g on a calibrated balance scale (Denver Instrument, Bohemia, NY). Drinks were housed in identical opaque containers containing one package of a commercially available, noncaloric lemon-flavored beverage (Crystal Light, Northfield, IL), 5 mg/kg of glucose, and 125mL of noncaloric 7-UP. The drinks appeared, smelled, and tasted similar. Participants were unaware of the order of treatments and were deceived of the true content of the drinks, as they were told that the study aim was to examine effects of a new carbohydrate beverage. This was done as placebo effects of caffeine have been revealed. Participants were provided their solution for the first day of testing during their last familiarization trial, and this process ensued during remaining trials. They were provided specific instructions with each drink to mix it with 250mL of cold water and drink it within a 5-minute period 1 hour prior to exercise. They returned empty bottles on the day of each trial to verify drink ingestion, and underwent a brief interview with the primary investigator to ensure that drink timing and ingestion were proper. Monitoring of Exercise Status and Dietary Intake Initially, participants were instructed how to complete 24-hour dietary logs before each trial, and were asked to follow the same diet on the day before each trial. These were photocopied and returned to participants everyday, and they were required to confirm maintenance of their diet as on arrival to the lab; their food diary was qualitatively assessed by an investigator for compliance with these dietary guidelines prior to trial initiation. They were provided a list of items that contain caffeine (coffee, chocolate, soda, tea, energy drinks, etc., as well as common over-the-counter medications) so they refrained from caffeine intake for 48 hours before each visit. Before each trial, they did not complete intense exercise in the preceding 48 hours and fasted for 3 hours. This was confirmed through completion of formal questionnaires submitted on each visit. Participants were provided a training log in which they denoted all physical activity completed during the course of the study, and were instructed to maintain their current exercise volume and intensity during the study. Statistical Analysis Data are reported as mean – standard deviation and were analyzed using SPSS 17.0 (Chicago, IL). One-way analysis of variance (ANOVA) with repeated measures was used to assess differences in time-trial performance across treatments (C1, C2, and placebo), with fitness level used as a between-subjects variable. Potential order effects of treatment ingestion on time-trial performance were examined with a one-way ANOVA with repeated measures. Two-way repeated measures ANOVA was used to examine differences in HR and RPE across time and treatment, with fitness level used as a between-subjects variable. The Greenhouse-Geisser correction was used to account for the sphericity assumption of unequal variances across groups. If a significant F ratio was obtained, Tukey’s post hoc test was used to detect significant differences between means. Independent t-test was used to examine differences in various parameters when applicable. Effect size for the F ratio was expressed as partial eta-squared (g2). Statistical significance was set at p < 0.05.
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How many outcome-specific endpoints are evaluated? 1
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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
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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 telemetry
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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.) Each participant received the same treatment and 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 competing financial interests exist in execution of this study.
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Refid 10042
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What were the sources of funding? The experimenters thank the subjects for participating in the current study, which was partially funded by a College of Arts and Sciences Faculty Development Grant.
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Results & Comparisons

No Results found.