The Repeatability of the Effect of Caffeine Supplementation on Submaximal Physiological Responses and Cycling Time Trial Performance

Not Applicable

Not yet recruiting

• Conditions: Caffeine

• Registration Number: NCT06935214
• Lead Sponsor: St. Mary's University, Twickenham

Brief Summary

Recently, Grgic (2018) discussed the concept of responders and non-responders to caffeine supplementation highlighting the importance of the repeatability of results. However, the number of studies that have investigated this idea by repeating the same time-trial performance test multiple times with the same caffeine dose is sparse (Astorino et al., 2012; Del Coso et al., 2019). Furthermore, studies have shown that differences in the CYP1A2 genotype may account for some of the variation in time-trial performance (Guest et al., 2018). Thus, the current study aims to identify whether the effects of moderate caffeine supplementation (5 mg/kg) on time-trial performance are repeatable to aid the identification of responders and non-responders. Additionally, the study aims to determine if the CYP1A2 genotype may explain any of the variability in time-trial performance in trained male cyclists.

Detailed Description

Not available

Study Timeline

• Status Verified: 2025-04
• Study First Submitted: 2025-04-11
• Study First Submitted QC: 2025-04-11
• Last Update Submitted: 2025-04-11
• Study First Posted: 2025-04-20
• Last Update Posted: 2025-04-20
• Study Start: 2025-05-01
• Primary Completion: 2025-08-23
• Study Completion: 2025-12-31

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: Male
• Target Recruitment: 12

Inclusion Criteria

• To be considered for inclusion in the study, participants must be regular cyclists, between 18 and 35 years of age, capable of completing a 20 km cycling time trial at a minimum speed of 30 km/h (arbitrary inclusion criteria to ensure a sufficient standard of athlete).

Exclusion Criteria

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Blood lactate concentration	From baseline to completion, up to 31 days	Description: Change from baseline in blood lactate concentration measured at rest and at six different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Heart rate	From baseline to completion, up to 31 days	Change from baseline in heart rate measured at rest and at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer.
Oxygen uptake	From baseline to completion, up to 31 days	Change from baseline in oxygen uptake measured at rest and at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Perceived exertion	From baseline to completion, up to 31 days	Change from baseline in rating of perceived exertion measured (using the 6-20 Borg scale) at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Time trial completion time	From baseline to completion, up to 31 days	Change from baseline in time to complete a time trial at a target amount of work on an electromagnetically-braked cycle ergometer calculated from the power output at maximal oxygen uptake and designed to last approximately 25 minutes.