Caffeine Strategies and Fat Oxidation

Official title

Effects of Different Caffeine Ingestion Forms on Fat Oxidation During Cycle Ergometer Exercise

Overview

The goal of this clinical trial is to learn if different forms of caffeine ingestion can influence fat oxidation during submaximal cycling exercise. The study will recruit healthy adults, both men and women, aged 18 to 50, who regularly perform aerobic exercise. The main questions it aims to answer are: * Does caffeine increase fat oxidation during one hour of cycling at the Fatmax intensity? * Do different forms of caffeine ingestion (capsule, coffee, chewing gum, or mouth rinse) differ in their effect on fat oxidation? * Do these caffeine forms alter total energy expenditure, cardiorespiratory response, or perceived exertion during exercise? * Are there differences in the occurrence or severity of side effects between caffeine administration methods? Researchers will compare each caffeine form to its corresponding placebo to determine their effects on fat oxidation and other physiological outcomes. Participants will: * Attend a pre-experimental session to determine their Fatmax intensity and VO₂max using an incremental cycling test * Perform eight experimental sessions, each consisting of one hour of cycling at Fatmax intensity * Receive caffeine or placebo via capsules, coffee, chewing gum, or mouth rinse according to a randomized, double-blind, crossover design * Be monitored for fat and carbohydrate oxidation, total energy expenditure, heart rate, and perceived exertion during exercise * Report any side effects immediately after the session and 24 hours later using a structured questionnaire All sessions will be conducted under controlled laboratory conditions with standardized protocols to ensure safety and reliable measurements.

Interventions

• Drug Caffeine (Guinama Anhydrous Powder)
  3 mg/kg of anhydrous caffeine powder (Guinama, Spain) administered in an opaque capsule 60 min before exercise.
• Dietary supplement Caffeine (Nescafé Classic Coffee)
  3 mg/kg of caffeine via Nescafé Classic (Nestlé, Switzerland) dissolved in 250 mL of water 60 min before exercise.
• Dietary supplement Caffeine (Kafewake Gum)
  3 mg/kg of caffeine via Kafewake gum (Arafarma group, Spain), chewed for 10 min before exercise.
• Other Caffeine Mouth Rinse Solution
  3 mg/kg of caffeine (Nescafé Classic) dissolved in 25 mL of water for a 20-second rinse before exercise.
• Other Placebo (Cellulose Capsule)
  Opaque capsule containing cellulose powder, matching caffeine capsules, taken 60 min before exercise.
• Other Placebo (Decaffeinated Coffee)
  Decaffeinated Nescafé (Nestlé, Switzerland) in 250 mL of water, matching caffeinated coffee, taken 60 min before.
• Other Placebo (Non-caffeine Gum)
  Kafewake Non-caffeinated gum (Arafarma group, Spain) with identical taste and texture, chewed for 10 min before.
• Other Placebo Mouth Rinse Solution
  Decaffeinated Nescafé in 25 mL of water for a 20-second rinse immediately before exercise.

Primary outcome measures

• Rate of fat oxidation during submaximal cycling exercise at Fatmax intensity [Time frame: 1 hour per experimental session]

Secondary outcome measures (8)

• Rate of carbohydrate oxidation during submaximal cycling exercise at Fatmax intensity [Time frame: 1 hour per experimental session]
• Total energy expenditure during exercise [Time frame: 1 hour per experimental session]
• Mean Exercise Heart Rate [Time frame: 1 hour per experimental session]
• Oxygen consumption [Time frame: 1 hour per experimental session]
• Carbon Dioxide Production [Time frame: 1 hour per experimental session]
• Blood lactate concentration [Time frame: Every 20 minutes during each 1-hour session]
• Rating of Perceived Exertion (RPE) during exercise [Time frame: Every 10 minutes during each 1-hour session]
• Occurrence of caffeine-related side effects [Time frame: Immediately after each session and 24 hours post-exercise]

Eligibility criteria

Inclusion criteria

• Healthy men and women aged 18-50 years
• Regular aerobic exercise at least 1 hour per day, 2 days per week
• Provide written informed consent

Exclusion criteria

• Smoking
• Use of medication or ergogenic supplements during the study period
• Caffeine intolerance or allergy
• Cardiopulmonary or musculoskeletal disorders
• Use of oral contraceptives in female participants

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Double blind

Primary purpose

Basic science

Study locations

Spain · 1 center

• Estadio Raúl González Blanco, Camino del Molino 5 — Fuenlabrada

Publications

• Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins NDM, Arent SM, Antonio J, Stout JR, Trexler ET, Smith-Ryan AE, Goldstein ER, Kalman DS, Campbell BI. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021 Jan 2;18(1):1. doi: 10.1186/s12970-020-00383-4. PMID 33388079
• Ruiz-Moreno C, Gutierrez-Hellin J, Amaro-Gahete FJ, Gonzalez-Garcia J, Giraldez-Costas V, Perez-Garcia V, Del Coso J. Caffeine increases whole-body fat oxidation during 1 h of cycling at Fatmax. Eur J Nutr. 2021 Jun;60(4):2077-2085. doi: 10.1007/s00394-020-02393-z. Epub 2020 Oct 6. PMID 33025051

Identifiers

NCT: NCT07402902 · URJC-CAF-FOX-2026

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗