Study Preview
Study Title and Description
Caffeine supplementation and multiple sprint running performance.
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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| Title | Caffeine supplementation and multiple sprint running performance. |
| Author | M Glaister,G Howatson,CS Abraham,RA Lockey,JE Goodwin,P Foley,G McInnes, |
| Country | |
| Year | 2008 |
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Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Cardiovascular Design
| Question... Follow Up | Answer | Follow-up Answer | |
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| 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 this study was to examine the effects of caffeine supplementation on multiple sprint running 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: Twenty-one male sport science students volunteered for the study. Before testing, subjects received written and verbal instructions regarding the nature of the investigation and completed a training history questionnaire, which indicated that all had been actively involved in sport for approximately 13 yr and that most (n = 19) regularly participated in some form of multiple sprint sport. Means +/- SD for age, height, body mass, and body fat (13) of the subjects were 21 +/- 3 yr, 177.4 +/- 5.9 cm, 77.7 +/- 13.5 kg, and 14.6 +/- 5.3%, respectively. Experimental procedure: All subjects completed four trials of the multiple sprint test, which consisted of 12 _ 30-m straight-line sprints repeated at 35-s intervals. Trial 1 was a familiarization test to limit the effects of learning on the outcome of the experiment. Trial 2 was a baseline test to enable the effects of both caffeine and placebo to be evaluated. Trials 3 and 4 were the experimental trials that were randomized and conducted in a double-blind manner. All trials were completed at approximately the same time of day, with a minimum of 4 d between trials. Subjects were instructed to maintain their normal diet throughout the testing period to avoid food and drink in the hour before testing and to avoid strenuous exercise 24 h before each trial. Subjects were provided with a list of dietary sources of caffeine and asked to refrain from consuming these 48 h before each trial. A questionnaire was used to establish typical daily caffeine consumption. On arrival at the testing facility, with the exception of the familiarization trial, resting blood samples (~5 mL) were drawn from a branch of the basilic vein and collected in plain siliconized tubes. In trials 3 and 4, subjects were subsequently administered a gelatin capsule containing either 5 mg/kg of caffeine (Sigma-Aldrich, Steinheim, Germany) or the same volume (4 mg/kg) and color of placebo (maltodextrin; Starmax Nutrition, Hereford, UK) 1 h before testing. After trial 4, subjects were asked if they could distinguish between the two supplements, and if so, to identify the basis of that decision. Nine subjects correctly identified the caffeine trial post hoc . Common explanatory characteristics were terms such as ‘‘energized,’’ ‘‘boosted,’’ and ‘‘fidgety.’ Heart rates were monitored continuously during each test using heart rate monitors (Polar S610; Polar Electro Oy, Kempele, Finland). Heart rate transmissions were synchronized with the audio signals to provide direct comparisons between trials. |
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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 | Heart rates were monitored continuously during each test using heart rate monitors (Polar S610; Polar Electro Oy, Kempele, Finland). Heart rate transmissions were synchronized with the audio signals to provide direct comparisons between trials. |
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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.) | Placbo given maltodextrin. Also subjects were tested at baseline. |
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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) | A two-way (supplement x sprint number) ANOVA with repeated measures on both factors was used to evaluate the effects of caffeine on multiple sprint performance. Analyses for measures of blood lactate and RPE were similar to those for measures of performance except that the factors of ‘‘supplement’’ and ‘‘sprint number’’ were replaced with those of ‘‘trial’’ (three levels) and ‘‘time.’’ The effects of caffeine supplementation on plasma caffeine (including primary metabolites of paraxanthine, theophyline, and theobromine), heart rate, and summary multiple sprint data (fastest time, mean time, and fatigue) were determined using one-way ANOVA with repeated measures. > was set at 0.05 for all analyses with Bonferroni adjustments for multiple comparisons. The possibility that the effects of caffeine supplementation on performance were influenced by habitual caffeine consumption was investigated by deriving correlations between estimated daily caffeine consumption and caffeine-induced changes (relative to placebo) in summary multiple sprint data. Correlation coefficients were interpreted in accordance with the following scale of magnitudes as devised by Cohen (4): r < 0.1 is trivial; 0.1 </= r < 0.3 is small; 0.3 </= r < 0.5 is moderate; and r >/= 0.5 is large. The above analyses provided 95% confidence interval for all estimates. |
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| What conflicts of interest were reported? | Not discussed. |
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| Refid | 18799995 |
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| What were the sources of funding? | Not mentioned. |
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Results & Comparisons
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