Study Title and Description
Effects of caffeine on session ratings of perceived exertion.
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 session ratings of perceived exertion.|
|Author||LG Killen,JM Green,EK O'Neal,JR McIntosh,J Hornsby,TE Coates,|
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)?||The purpose of the current study was to determine the effects of caffeine ingestion (6 mg/kg body weight) on session ratings of perceived exertion (RPE).|
|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 Fifteen individuals (males: n = 10, females: n = 5) of varying aerobic fitness volunteered as participants. All procedures were approved by the local review board for the protection of human subjects and each participant signed a written informed consent outlining study requirements before initiation of data collection. Participants reported to the lab with instructions to be well rested (C24 h with no heavy physical activity) and well hydrated. Each participant received two 473 mL bottles of water: one to be consumed between dinner and bed the night prior to the trial and the other within an hour of reporting to the lab. Water was administered in attempt to ensure participants reported adequately hydrated in both trials. The caffeine and placebo capsules were administered in sealed containers prior to each trial. Placebo capsules contained maltodextrin and were identical in appearance with the caffeine capsules. Additionally, participants consumed the exact number of capsules for each trial. They were also instructed to avoid alcohol and caffeine (excluding treatment) 4 days (Fisher 1986) prior to each testing session. Each participant completed a survey to determine the amount of caffeine consumed over an average of five days. This information was also used to identify habitual caffeine users. Upon completion of each trial (caffeine and placebo), a questionnaire using a ten-point Likert scale was administered (Hudson et al. 2008). For each question a response of zero indicated the symptom was ‘‘not at all experienced’’ with ten indicating the symptom was ‘‘extremely’’ experienced. The questionnaire was used to determine if the participant experienced any adverse symptoms (fatigue, elevated mood, nervousness, restlessness, tremors, stomach distress) and to what degree the symptoms had been experienced as a result of caffeine consumption. Statistical analysis Means and standard deviations for descriptive characteristics of participants were calculated. Subjective responses from the post-trial questionnaire were compared using a paired t test for each dependent measure. Results were considered significant at p\0.05.|
|How many outcome-specific endpoints are evaluated?||3|
|What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately)||fatigue|
|List additional health endpoints (separately).|
|List additional health endpoints (separately)|
|Notes||also measured elevated mood, tremors and stomach distress|
|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||Likert scale was administered (Hudson et al. 2008). For each question a response of zero indicated the symptom was ‘‘not at all experienced’’ with ten indicating the symptom was ‘‘extremely’’ experienced. The questionnaire was used to determine if the participant experienced any adverse symptoms (fatigue, elevated mood, nervousness, restlessness, tremors, stomach distress) and to what degree the symptoms had been experienced as a result of caffeine consumption.|
|Caffeine (general)||Caffeine (general)|
|What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.)||placebo (0 mg caffeine) vs 6 mg/kg caffeine|
|What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models. Copy from methods)||N/A|
|Provide a general description of results (as reported by the authors).||Regarding subjective responses on the post-exercise survey, feelings of fatigue were significantly lower for caffeine (Fig. 6) while nervousness, restlessness, stomach distress, and tremors were significantly higher for caffeine (Fig. 6). Subjective responses for ‘elevated mood’ between caffeine and placebo trials approached but did not reach a priori level of significance for caffeine at p = 0.11.|
|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?||Participants reported feeling significantly more nervous and restless while also reporting more tremors and stomach distress (Fig. 6). Hudson et al. (2008) found similar results with participants reporting significant increases in restlessness, tremors, and stomach distress.|
|What were the sources of funding?||None listed.|
|What conflicts of interest were reported?||N/A|
|Does the exposure (dose) need to be standardized to the SR?||Multiple metrics|
|Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest).||mean body weight (as listed by study) = 74 kg 6 mg/kg caffeine = 6 mg/kg * 74 kg = 444 mg caffeine|
|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.||nervous - LOAEL = 444 mg/day restless - LOAEL = 444 mg/day fatigue - NOAEL = 444 mg/day|
|Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot.||ratings for fatigue improved following caffeine use|
|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.