Study Title and Description
Effects of caffeine on repeated sprint ability, reactive agility time, sleep and next day 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 behavior*?|
Primary Publication Information
|Title||Effects of caffeine on repeated sprint ability, reactive agility time, sleep and next day performance.|
|Author||KJ Pontifex,KE Wallman,BT Dawson,C Goodman,|
Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Behavior - Design Details - INCLUDED Studies
No arms have been defined in this extraction form.
|Question... Follow Up||Answer||Follow-up Answer|
|What outcome is being evaluated in this paper?||Behavior|
|What is the objective of the study (as reported by the authors)?||This study assessed the effects of caffeine on repeated sprint ability (RSA), reactive agility time (RAT), sleep and next day exercise performance.|
|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)||In order to allow for baseline comparisons and assessment of regular caffeine consumption, participants were required to keep a record of their food intake, physical activity levels and sleep patterns over four consecutive weekday nights. Participants took part in two exercise trials (caffeine and placebo) held between 5.00 and 8.00 p.m., performed seven days apart in a single-blind, randomized crossover design. Participants arrived 2 h prior to testing,at which time they were given 1 g.kg-1bm of 100% glucose powder (Glucodin, Boots Healthcare, NSW, Australia) to consume with 1L water within 30 min. One hour prior to exercise testing, whilst blindfolded, participants ingested 6 mg.kg-1bm of caffeine (No-Doz Awakeners, Key Pharmaceuticals, NSW, Australia) or placebo contained in opaque gelatin capsules (Tyco Healthcare Pty Ltd, NSW, Australia). That night the participant collected a pre-bedtime midstream urine sample (for caffeine assay) and wore a sleep actigraph wrist watch (Micro Mini-Motion Logger, Ambulatory Monitoring Inc., Ardsley, NY, USA) to bed. Midstream urine samples were collected by the participants before retiring to sleep on the night of testing. This measurement allowed for the assessment of the relative rate of caffeine metabolism between participants,as well as assisted in determining whether the remaining caffeine concentrations were sufficient to affect sleep quantity and quality. Urine samples were frozen and individually analysed for urinary caffeine concentration using high-performance liquid chromatography (Waters Corporation instrument, Milford, MA, USA), a technique used in a recent study from our laboratory. Sleep duration (SLD), sleep efficiency (SE), number of wakings (NW) and total wake time after sleep onset (WT) were measured using a wrist-worn actigraph. Sleep parameters were assessed during a four day baseline trial measured a week prior to the start of the exercise trials, as well as on the night following the first day of the exercise trials.|
|How many outcome-specific endpoints are evaluated?||1|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||Sleep|
|List additional health endpoints (separately).|
|List additional health endpoints (separately)|
|Notes||Sleep endpoints included: sleep duration, wake time, number of wakings, and sleep efficiency|
|What is the study design?||Controlled Trial|
|Randomized or Non-Randomized?||RCT|
|What were the diagnostics or methods used to measure the outcome?||Subjective|
|Optional: Name of Method or short description||Sleep outcomes assessed by actigraph wrist watch|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||Study compared baseline results to caffeine trial (6 mg/kg-bm)|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||None stated|
|Provide a general description of results (as reported by the authors).||Significant improvements were demonstrated after caffeine ingestion compared to placebo for the combined total time of each set (TT; combined sets 1, 3 ,5; 58.947 ± 1.88 vs. 59.683 ± 2.54 s, respectively; P=0.05), best sprint time (BT; next day performance; 3.176 ± 0.10 vs. 3.230 ± 0.12 s, respectively, P=0.01), and % decrement (combined sets 2, 4; 2.866 ± 1.24 vs. 3.801 ± 1.69 s, respectively; P=0.02). Moderate to strong effect sizes were found for % decrement for set 2 (Cohen’s d=-0.82; 1.312 ± 0.65 vs. 2.110 ± 1.20 s for caffeine and placebo conditions, respectively) and for sets 2 and 4 combined (Cohen’s d=-0.63; 2.866 ± 1.24 vs. 3.801 ± 1.69 for caffeine and placebo conditions, respectively). No significant differences were found for RAT or for sleep measures (P>0.05).|
|Did the authors perform a dose-response analysis (or trend/related analysis)?||No|
|What were the authors's observations re: trend analysis?|
|What were the author's conclusions?||Caffeine improved RSA, including next day performance, but had little effect on RAT or sleep parameters.|
|What were the sources of funding?||This research was funded entirely by the University of Western Australia|
|What conflicts of interest were reported?||None reported|
|Does the exposure (dose) need to be standardized to the SR?||Yes|
|Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).||Assume avg bw of 80 kg for adults. 80 kg x 6 mg/kg = 480 mg|
|List all the endpoint(s) followed by the dose (mg) which will be used in comparison to Nawrot. Characterize value as LOAEL/NOAEL, etc. if possible.||Sleep NOAEL = 480 mg (sleep duration, wake time, number of wakings, or sleep efficiency)|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.|
|What is the importance of the study with respect to the adverseness of the outcome?||Important|
No baseline characteristics have been defined for this extraction form.
Results & Comparisons
No Results found.
|Arm or Total||Title||Description||Comments|
No quality dimensions were specified.
No quality rating data was found.