Caffeine Increases Maximal Fat Oxidation During Exercise in Endurance-trained Men: is There a Diurnal Variation

Study Overview
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Brief Summary
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Maximal fat oxidation during exercise (MFO) and the intensity of exercise that elicits MFO (Fatmax) has been recognized as potential determinants of endurance performance. The purpose of this study was to determine the possible interaction between the effects of diurnal variation (morning vs. afternoon) and caffeine ingestion on MFO, Fatmax and VO2 max in endurance-trained men. Specifically, the investigators sought to elucidate whether the stimulant actions of caffeine could reverse the decrements of MFO and Fatmax observed in the morning.

Detailed Description
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Body weight, height, body composition (DXA), exercise test (MFO and VO2max assessment) will be measured during the 4 evaluations. Participants were randomized into 4 exercise test conditions: Exercise test in the morning with placebo intake Exercise test in the evening with placebo intake Exercise test in the morning with caffeine intake Execrise test in the evening with caffeine intake

Official Title
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Caffeine Increases Maximal Fat Oxidation During Exercise in Endurance-trained Men: is There a Diurnal Variation

Conditions
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Energy Metabolism, Athletic Performance

Intervention / Treatment
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* Behavioral: Test in the morning
* Behavioral: Test in the afternoon


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Having a body mass index (BMI) ranged from 18.5 to 28 kg/m2 not suffering any specific disease which can be aggravated by physical exercise having previous experience in endurance training (i.e. self-reporting at least 2 years of cycling or running training including more than 3 training sessions/week). Participant must be capable and willing to provide consent, understand exclusion criteria, instructions and protocols. Exclusion Criteria: Being smoker Taking medication or drugs Any non-controlled medical condition which could influence results or could be worsened by the participation in the study Are deemed unsuitable by the investigator for any other reason, that prevent data collection.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Caffeine<br>A dose of 3 mg/kg of caffeine (i.e. a vegetable extraction from green coffee beans, Harrison Sport Nutrition®, Spain) was ingested before the beginning of each test. | Behavioral: Test in the morning<br>* The exercise test was performed between 8 a.m and 11 a.m<br>* Other names: MFO-morning, Fatmax-morning, and VO2max-morning;Behavioral: Test in the afternoon<br>* The exercise test was performed between 5 p.m. and 8 p.m.a<br>* Other names: (MFO-afternoon, Fatmax-afternoon, and VO2max-afternoon;|
| Placebo Comparator: Placebo<br>A dose of 3 mg/kg of placebo (i.e. 100% purity microcrystalline cellulose, Acofarma, Spain) was ingested before the beginning of each test. | Behavioral: Test in the morning<br>* The exercise test was performed between 8 a.m and 11 a.m<br>* Other names: MFO-morning, Fatmax-morning, and VO2max-morning;Behavioral: Test in the afternoon<br>* The exercise test was performed between 5 p.m. and 8 p.m.a<br>* Other names: (MFO-afternoon, Fatmax-afternoon, and VO2max-afternoon;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| MFO | Maximal fat oxidation during exercise | Through study completion, an average of 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| FATmax | The intensity of exercise that elicits MFO | Through study completion, an average of 1 month | 
| VO2max | Cardiorrespiratory fitness measured by maximal oxygen uptake | Through study completion, an average of 1 month |