Study Preview
Study Title and Description
A moderate dose of caffeine ingestion does not change energy expenditure but decreases sleep time in physically active males: a double-blind randomized controlled trial.
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*? |
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Primary Publication Information
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| Title | A moderate dose of caffeine ingestion does not change energy expenditure but decreases sleep time in physically active males: a double-blind randomized controlled trial. |
| Author | PB Júdice,JP Magalhães,DA Santos,CN Matias,AI Carita,PA Armada-Da-Silva,LB Sardinha,AM Silva, |
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| Year | 2013 |
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Secondary Publication Information
There are currently no secondary publications defined for this study.
Extraction Form: Behavior - Design Details - INCLUDED Studies
Arms
No arms have been defined in this extraction form.
| Question... Follow Up | Answer | Follow-up Answer | |
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| Refid | 23368828 |
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| What outcome is being evaluated in this paper? | Behavior |
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| What is the objective of the study (as reported by the authors)? | Therefore, we aimed to analyze the impact of a moderate dose of caffeine during a 4-day period on Total Sleep Time, resting energy expenditure (REE), PA energy expenditure (PAEE), total energy expenditure (TEE), and daily time spent in sedentary (ST), light (LPA), moderate (MPA), and vigorous (VPA) intensity activities in nonobese, physically active males in free-living conditions. In addition, we also investigated the acute effects of caffeine on heart rate (HR) and EE at the second hour after administration in free-living conditions. |
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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 A total of 30 healthy young adult males aged between 20 and 39 years volunteered to participate in this study. Inclusion criteria were body mass index (BMI) between 18.5 and 29.9 kg/m2, nonsmokers, and not taking any medications or dietary supplements that may affect energy expenditure. In addition, participants were low-caffeine users (<100 mg/day) (Currie et al. 1995). Experimental design Participants were followed in a double-blind crossover experimental design with two conditions in a random sequence: caffeine (5 mg/kg body mass/day) and maltodextrin as placebo, both through capsules. Each condition lasted for 4 days, and participants were instructed to keep the same eating patterns and level of PA. There was a washout period of 3 days between each condition. Moreover, to reduce the variability of individual PA patterns during the week, both conditions were performed on the same weekdays while the washout period always included the weekend days. Evaluations were performed at three time points: (i) baseline, first visit for collecting the initial measurements; (ii) condition 1, second visit, 4 days after baseline, for collecting the final measurements of the first randomly assigned condition (placebo or caffeine); and (iii) condition 2, third visit, 7 days after the end of the first condition, including the 3-day washout period, for collecting the final measurements of the second randomly assigned condition (placebo or caffeine). Caffeine and placebo intake After the participants were weighed, the dose was individually prepared to assure that 5 mg of caffeine per kilogram of body mass per day was administered. The dose of caffeine was divided into two equal parts (2.5 mg/kg) to be orally consumed through capsules in the morning and after lunch. An equivalent number of placebo capsules, of the same colour as the caffeine capsules, containing maltodextrin were provided for the placebo condition. Sleep time assessment Along with the use of both accelerometer and combined motion sensor, participants were provided with a worksheet to record the type and duration of physical activities performed and also the time that they went to sleep and woke up. The data from this self-reported information were checked with the combined motion sensor registration and the accelerometry data. The mean TST for the two conditions was determined, and the mean differences between conditions were considered as a potential confounder and also as dependent variable. |
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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) | sleep |
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| List additional health endpoints (separately). |
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| List additional health endpoints (separately) |
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| Notes | sleep is measured as total sleep time |
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| Clinical |
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| Physiological | Physiological |
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| Other |
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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? | Both |
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| Optional: Name of Method or short description | Along with the use of both accelerometer and combined motion sensor, participants were provided with a worksheet to record the type and duration of physical activities performed and also the time that they went to sleep and woke up. |
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| Caffeine (general) | Caffeine (general) |
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| Coffee |
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| Chocolate |
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| Energy drinks |
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| Gum |
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| Medicine/Supplement |
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| Soda |
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| Tea |
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| Measured | Measured |
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| Self-report |
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| Children |
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| Adolescents |
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| Adults | Adults |
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| Pregnant Women |
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| What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) | placebo (maltodextrin, 0 mg caffeine) vs 5 mg/kg caffeine (2 x 2.5 mg/kg per day) |
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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) | mean difference between objective and subjective measures of total sleep time fatfree mass, resting, and PA energy expenditure |
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| Provide a general description of results (as reported by the authors). | The results from ANOVA for repeated measures showed differences for TST between caffeine and placebo conditions (43 ± 97 min; F = 5.721, p = 0.022). |
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| Did the authors perform a dose-response analysis (or trend/related analysis)? | No |
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| What were the authors's observations re: trend analysis? |
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| What were the author's conclusions? | This was the first study that combined objective measures of total sleep time over a 4-day period under free-living conditions. Our findings showed that caffeine significantly decreased total sleep time, which is in accordance with previous data (Bracco et al. 1995; Calamaro et al. 2009; Drescher et al. 2011; Dulloo et al. 1999; Hursel et al. 2011; James 1998). So far, the effects of caffeine on TST have been investigated in laboratorial settings using objective measures (Bracco et al. 1995; Dulloo et al. 1999; Hursel et al. 2011), whereas self-reported data was used to assess TST under freeliving conditions (Calamaro et al. 2009; Drescher et al. 2011; James 1998). Moreover, under free-living conditions, a moderate dose of caffeine ingestion decreased TST. We further investigated if fat free mass, resting, and PA energy expenditure could have played a mediating role on these effects. After adjusting for these potential covariates, the significant reduction in total sleep time remained. |
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| What were the sources of funding? | This work was supported by the Hydration and Health Portuguese Institute |
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| What conflicts of interest were reported? | N/A |
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| Does the exposure (dose) need to be standardized to the SR? | Multiple metrics |
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| Provide calculations/conversions for the exposure based on the decision tree in the guide (for all endpoints/exposure levels of interest). | 5 mg/kg/day caffeine x 72.8 kg (average adult weight from study) = 364 mg/day caffeine |
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| 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 - LOAEL = 364 mg (reduction in total sleep time) |
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| Notes regarding selection/listing of endpoints and exposures/doses to be compared to Nawrot. | single (split) dose adverse effects, reduced total sleep time, seen at levels equal to Nawrot et al. |
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| What is the importance of the study with respect to the adverseness of the outcome? | Important |
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Baseline Characteristics
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Results & Comparisons
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Adverse Events
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