Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance.

Autor:	Boyett JC; Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA. boyettjc@dukes.jmu.edu., Giersch GE; Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA. gierscge@dukes.jmu.edu., Womack CJ; Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA. womackcx@jmu.edu., Saunders MJ; Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA. saundemj@jmu.edu., Hughey CA; Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA. hugheyca@jmu.edu., Daley HM; Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA. daleyhm@dukes.jmu.edu., Luden ND; Human Performance Lab, Department of Kinesiology, James Madison University, Harrisonburg, VA 22807, USA. ludennd@jmu.edu.
Jazyk:	angličtina
Zdroj:	Nutrients [Nutrients] 2016 Oct 14; Vol. 8 (10). Date of Electronic Publication: 2016 Oct 14.
DOI:	10.3390/nu8100639
Abstrakt:	This project was designed to assess the effects of time of day and training status on the benefits of caffeine supplementation for cycling performance. Twenty male subjects (Age, 25 years; Peak oxygen consumption, 57 mL·kg -1 ·min -1 ) were divided into tertiles based on training levels, with top and bottom tertiles designated as 'trained' ( n = 7) and 'untrained' ( n = 7). Subjects completed two familiarization trials and four experimental trials consisting of a computer-simulated 3-km cycling time trial (TT). The trials were performed in randomized order for each combination of time of day (morning and evening) and treatment (6mg/kg of caffeine or placebo). Magnitude-based inferences were used to evaluate all treatment effects. For all subjects, caffeine enhanced TT performance in the morning (2.3% ± 1.7%, 'very likely') and evening (1.4% ± 1.1%, 'likely'). Both untrained and trained subjects improved performance with caffeine supplementation in the morning (5.5% ± 4.3%, 'likely'; 1.0% ± 1.7%, 'likely', respectively), but only untrained subjects rode faster in the evening (2.9% ± 2.6%, 'likely'). Altogether, our observations indicate that trained athletes are more likely to derive ergogenic effects from caffeine in the morning than the evening. Further, untrained individuals appear to receive larger gains from caffeine in the evening than their trained counterparts. Competing Interests: The authors declare no conflict of interest.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu