Caffeine Mouth Rinsing at Different Doses in Female Team-Sport Athletes: A Randomized, Double-Blind, Placebo-Controlled Trial

Universidad Pontificia Comillas13 enrolled

Overview

Objective: To evaluate the effects of different caffeine mouth rinse concentrations (1%, 2%, and 3%) on Running Anaerobic Sprint Test (RAST) performance in female team-sport athletes. Main Questions: 1. Do caffeine mouth rinses improve RAST performance in female team-sport athletes? 2. Do different caffeine mouth rinse concentrations affect ratings of perceived exertion (RPE)? Method: Thirteen trained female football and handball players (23.0 ± 4.5 years) completed four randomized, double-blind, crossover conditions (1%, 2%, and 3% caffeine mouth rinses, and placebo). Each trial involved six 35 m sprints separated by 10 s of rest. RPE was recorded immediately after each session.

Objective: To evaluate the acute effects of different caffeine mouth rinse concentrations (1%, 2%, and 3%) on anaerobic sprint performance and perceived exertion in trained female team-sport athletes. The study sought to determine whether this non-ingestive ergogenic strategy could enhance high-intensity running performance and reduce effort perception. Main Questions: 1. Do different caffeine mouth rinse concentrations improve Running Anaerobic Sprint Test (RAST) performance in trained female team-sport athletes? 2. Do caffeine mouth rinses at varying concentrations influence ratings of perceived exertion (RPE) compared with placebo? Is there an optimal caffeine concentration that balances potential performance benefits with reduced perceived exertion? Method: Thirteen trained female athletes (mean age 23.0 ± 4.5 years) competing in football and handball participated in a randomized, double-blind, placebo-controlled, crossover trial. Each athlete completed four experimental conditions: placebo, 1% caffeine mouth rinse, 2% caffeine mouth rinse, and 3% caffeine mouth rinse. In each session, participants performed a Running Anaerobic Sprint Test (RAST) consisting of six maximal 35 m sprints separated by 10 seconds of passive recovery. The RPE was assessed immediately after each test using a 1-10 scale.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

Interventions

Placebo: Mouth rinse with plain waterDIETARY_SUPPLEMENT

Placebo: Mouth rinse with plain water, containing no caffeine, serving as the control condition.

Experimental: Low mouth rinse caffeine concentration (1%)DIETARY_SUPPLEMENT

Arm Description: Low caffeine concentration: Mouth rinse containing 1% caffeine solution (based on weight/volume).

Moderate caffeine concentration (2% caffeine solution weight/volume).DIETARY_SUPPLEMENT

Moderate caffeine concentration: Mouth rinse containing 2% caffeine solution (weight/volume).

High caffeine concentration (3% caffeine solution weight/volume).DIETARY_SUPPLEMENT

High caffeine concentration: Mouth rinse containing 3% caffeine solution (weight/volume).

Eligibility

Sex: FEMALEMin age: 18 YearsMax age: 35 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria * Female team sports athletes aged between 18 and 35 years. * Currently engaged in team sports. * Non-smoker. Exclusion Criteria * Participants were excluded if they met any of the following conditions. * Presence of a musculoskeletal injury within the six months prior to the study. * Current smoker. * Use of nutritional supplements or ergogenic aids that could influence sprint running performance (e.g., beta-alanine, creatine). * Use of oral contraceptives. * Known allergy to caffeine. * Failure to meet the training requirement of at least six hours of team-based practice, a minimum of three days per week, over the past year.

Outcomes

Primary Outcomes

Running-based anaerobic sprint test (RAST protocol)

The RAST was comprised of six 35 m sprints at maximum effort, each of which was followed by a 10 s passive rest period (including deceleration phase). Participants rinsed the solution in the final 5 s of the rest period accompanied by the counting of the tester, and then sprint back to the first timing gate with "GO" command. This was repeated until six sprints had been accomplished. Participants began to sprint running for a maximum of one step before the timing gate and were instructed not to decelerate before passing through the timing gate. Using a system of photocells (Newtest Powertimer 300-series, Newtest Oy, Tyrnävä, Finland), which was placed at the beginning and the end of the 35 m, the duration of each 35 m sprint running time was recorded. Using time of each sprint attempt, 1-) fastest sprint time, 2-) mean sprint time, and 3-) fatigue index were recorded

Time frame: 2-week

Secondary Outcomes

Rating of perceived exertion (RPE)

Perceived exertion during each trial was assessed immediately after the Running Anaerobic Sprint Test (RAST) using a 1-10 numerical scale points, where: 1 = Very, very light effort (minimal exertion, easy to continue) 2-3 = Light effort (comfortable, mild strain) 4-5 = Moderate effort (noticeable breathing and muscle activation) 6-7 = Hard effort (challenging but sustainable for a short time) 8-9 = Very hard effort (significant discomfort, near maximal effort) 10 = Maximal effort (unable to continue beyond current level, exhaustion) This scale provided a subjective measure of the athletes' internal load, complementing the objective performance metrics from the sprint test.

Time frame: 2-weeks