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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Caffeine | Experimental | 5 mg/kg dose of caffeine (in pill form) - Trial 1 |
|
| Placebo | Placebo Comparator | 5 mg/kg dose of placebo (Maltodextrin in pill form) - Trial 2 |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Caffeine | Dietary Supplement | 5 mg/kg of caffeine in pill form |
| |
| Measure | Description | Time Frame |
|---|---|---|
| Blood lactate concentration | 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 | From baseline to completion, up to 31 days |
| Heart rate | 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. | From baseline to completion, up to 31 days |
| Oxygen uptake | 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 | From baseline to completion, up to 31 days |
| Perceived exertion | 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 | From baseline to completion, up to 31 days |
| Time trial completion time | 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. | From baseline to completion, up to 31 days |
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Inclusion Criteria:
Exclusion Criteria:
-
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| ID | Term |
|---|---|
| D002110 | Caffeine |
| ID | Term |
|---|---|
| D014970 | Xanthines |
| D000470 | Alkaloids |
| D006571 | Heterocyclic Compounds |
| D011688 | Purinones |
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| Placebo |
| Dietary Supplement |
5 mg/kg dose of maltodextrin in pill form |
|
| Caffeine | Dietary Supplement | 5 mg/kg dose of caffeine in pill form |
|
| D011687 |
| Purines |
| D006574 | Heterocyclic Compounds, 2-Ring |
| D000072471 | Heterocyclic Compounds, Fused-Ring |