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

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.