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The impact of caffeine habituation on acute responses to different doses of caffeinated coffee has received minimal attention. This study aimed to investigate the effects of different doses of coffee on physical and cognitive performance in men and women with different levels of daily caffeine consumption. Sixty-nine (35 women) athletes participated in this study, attending 4 experimental visits in a double-blind, randomized, crossover fashion: decaffeinated coffee (PLA), 1.5 mg·kg-1 (LCOF), 3 mg·kg-1 (MCOF) and 6 mg·kg-1 of caffeine (HCOF) from coffee ingestion. Sixty min after coffee consumption, participants performed squat and bench press exercises (1 repetition maximum, 1RM), 60% of 1RM muscular endurance (ME), maximal sprinting, and cognitive performance (CP) was assessed. Participants were allocated into low (LGROUP), moderate (MGROUP), and high (HGROUP) caffeine consumption groups.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Low dose caffeine supplementation | Experimental | consuming 0.12 g·kg-1 of decaffeinated coffee + 0.04 g·kg-1 of caffeinated coffee to achieve 1.5 mg·kg-1 of caffeine intake 60-min before the experimental trial. |
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| Moderate dose caffeine supplementation | Experimental | Consuming 0.08 g·kg-1 of decaffeinated coffee + 0.08 g·kg-1 of caffeinated coffee to achieve 3 mg·kg-1 of caffeine intake 60-min before the experimental trial. |
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| High dose caffeine supplementation | Experimental | Consuming 0.16 g·kg-1 of caffeinated coffee to achieve 6 mg·kg-1 of caffeine intake 60-min before the experimental trial. |
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| Placebo | Experimental | Consuming 0.16 g·kg-1 of decaffeinated coffee 60-min before the experimental trial. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Low Dose Caffeine (LCOF) | Dietary Supplement | Caffeinated versions of instant coffee were prepared in 600 ml hot water (approximately 65°C) and served in a mug. Participants ingested 0.12 g·kg-1 of decaffeinated coffee + 0.04 g·kg-1 of caffeinated coffee to achieve 1.5 mg·kg-1 of caffeine intake in LCOF 60-min before the experimental trial. |
| Measure | Description | Time Frame |
|---|---|---|
| Upper- and Lower-boy muscular endurance | Muscular endurance assessed during bench press and squat exercises using 60% of one-repetition maximum (1RM). Performance expressed as total weight lifted (kg). | 60 minutes after caffeine or placebo ingestion (during each experimental trial) |
| Upper- and lower-body strenght | Maximal dynamic strength assessed using one-repetition maximum (1RM) tests in the squat and bench press exercises (kg). | 60 minutes after caffeine or placebo ingestion (during each experimental trial) |
| Measure | Description | Time Frame |
|---|---|---|
| Sprint Performance | Peak power output and mean power output measured during a 15-second Wingate anaerobic test on a cycle ergometer (W/kg). | 60 minutes after caffeine or placebo ingestion (during each experimental trial) |
| Cognitive performance |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Ankara University's Department of Sports Science | Ankara | Turkey (Türkiye) |
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| ID | Term |
|---|---|
| D009043 | Motor Activity |
| ID | Term |
|---|---|
| D001519 | Behavior |
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| ID | Term |
|---|---|
| D002110 | Caffeine |
| ID | Term |
|---|---|
| D014970 | Xanthines |
| D000470 | Alkaloids |
| D006571 | Heterocyclic Compounds |
| D011688 | Purinones |
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Supplements were allocated in a randomised order and double-blinding design was implemented by an independent technician who did not take part in the study. The randomisation and blinding were held until the end of the study.
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| Moderate Dose Caffeine (MCOF) | Dietary Supplement | Caffeinated versions of instant coffee were prepared in 600 ml hot water (approximately 65°C) and served in a mug. Participants ingested 0.08 g·kg-1 of decaffeinated coffee + 0.08 g·kg-1 of caffeinated coffee to achieve 3 mg·kg-1 of caffeine intake in MCOF 60-min before the experimental trial. |
|
| High Dose Caffeine (HCOF) | Dietary Supplement | Caffeinated versions of instant coffee were prepared in 600 ml hot water (approximately 65°C) and served in a mug. Participants ingested 0.16 g·kg-1 of caffeinated coffee to achieve 6 mg·kg-1 of caffeine intake in HCOF 60-min before the experimental trial. |
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| Placebo (PLA) | Dietary Supplement | Decaffeinated versions of instant coffee were prepared in 600 ml hot water (approximately 65°C) and served in a mug. Participants ingested 0.16 g·kg-1 of decaffeinated coffee in PLA 60-min before the experimental trial. |
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Reaction time (ms) and accuracy measured using a modified arrow flanker task.
| Baseline (before caffeine ingestion) and 60 minutes after caffeine or placebo ingestion. |
| D011687 |
| Purines |
| D006574 | Heterocyclic Compounds, 2-Ring |
| D000072471 | Heterocyclic Compounds, Fused-Ring |