Clinical trial NCT05632692: Menthol Mouth Rinsing and Performance Responses of Elite Football Referees in the Heat
Official title: Menthol Mouth Rinsing and Performance Responses of Elite Football Referees in the Heat: a Randomized Crossover Trial
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: NA
Conditions: Exercise Induced Hyperthermia
Performance Demands of Exercising in the Heat
Lead sponsor: Universidade do Porto
Sponsor class: OTHER
First posted: 2022-11-30
Enrollment: 10
Sex: MALE
Minimum age (years): 18
Maximum age (years): 45
Standard ages: ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: PREVENTION

Brief summary: Ten male football referees will be recruited to perform two intermittent football protocols , separated by at least 7 days (wash-out period). After passing the eligibility criteria, the participants will be randomly assigned, according to a computer-generated allocation schedule, to 1 of 2 beverages sequences: (1) intervention - menthol solution 0.01% (room temperature) and (2) placebo - noncaloric berry-flavoured solution (room temperature). The participants will be provided with one of the 2 beverages before warm-up (pre-cooling) and at the half-time (per-cooling). The trials will follow a randomised counterbalanced crossover design, blinded to the participants, and will take place in indoor facilities, where WBGT exceed 30◦C, at the same time of the day, to control for circadian variations. Each trial involves an exercise protocol (SAFT-90), lasting 90 minutes, separated into two 45-minute parts. The first half will be preceded by a warm-up and the second half by a 15-minute break.

The results of this study are expected to determine whether mouth rinsing a menthol solution, before a football exercise protocol performed in the heat, will help to alleviate physiological strain and improve performance parameters, comparing to a non-cooling strategy, in elite male football referees. Thus, we can be closer to defining nutritional strategies of internal cooling, that will be an advantage for the performance of the football referees, concretely in the competitions carried out under adverse environmental conditions.


Eligibility criteria: Inclusion Criteria:

1. Male football referees aged over 18 and under 45 years;
2. With normal weight (BMI ≥ 18.5 and ≤ 24.9 kg/m2);
3. Availability to participate in the introductory meeting, familiarization session and 2 experimental sessions;
4. Ability to read and sign the informed consent.

Exclusion Criteria:

1. Under the influence of any medications that may affect urinary parameters, thermoregulation mechanisms, circulatory system, thyroid and pituitary function or metabolic status;
2. Injury, diabetes, autoimmune disease, cardiovascular disease or obstructive disease of the gastrointestinal tract (e.g., diverticulitis, inflammatory bowel disease);
3. Schizophrenia, bipolar disorder or other psychotic disorders;
4. Eating disorders;
5. MRI scans scheduled within 48 hours after familiarization session or any of the experimental trials.

Primary outcomes:
measure: Heart rate change
timeFrame: A change in heart rate from baseline (immediately before exercise) to each 15-minute block of the exercise protocol will be assessed.
measure: Sweating rate at the first half
timeFrame: Sweating rate is going to be calculated at the end of the first half of the exercise protocol (after 45 min of exercise)
measure: Sweating rate at the second half
timeFrame: Sweating rate is going to be calculated at the end of the second half of the exercise protocol (after 90 min of exercise)
measure: Core temperature change
timeFrame: A change in core temperature from baseline (immediately before exercise) to each 15-minute block of the exercise protocol will be assessed
measure: Ratings of perceived exertion (RPE)
timeFrame: RPE is going to be accessed at the end of the exercise protocol.
measure: Thermal comfort (TC) change
timeFrame: A change in TC from baseline (immediately before intervention) to after intervention and to each 15-minute block of the exercise protocol will be assessed.
measure: Thermal sensation (TS) change
timeFrame: A change in TS from baseline (immediately before intervention) to after intervention and to each 15-minute block of the exercise protocol will be assessed.
measure: Perceived thirst (PT) change
timeFrame: A change in PT from baseline (immediately before intervention) to after intervention and to each 15-minute block of the exercise protocol will be assessed.
measure: Physical performance change
timeFrame: A change in each physical performance indicator from baseline (immediately after the warm-up) to each 15-minute block of the exercise protocol will be assessed
Secondary outcomes:
measure: Hydration status before
timeFrame: Hydration status is going to be recorder at baseline (pre-exercise)
measure: Hydration status after
timeFrame: Hydration status is going to be recorder at the end of the exercise protocol
measure: Ad libitum fluid intake at the first half
timeFrame: Ad libitum fluid intake is going to be assessed at the end of the first half of the exercise protocol (after 45 min of exercise)
measure: Ad libitum fluid intake at the second half
timeFrame: Ad libitum fluid intake is going to be assessed at the end of the second half of the exercise protocol (after 90 min of exercise)
measure: Blood lactate levels before
timeFrame: Blood lactate levels are going to be recorded before the start of the exercise protocol
measure: Blood glucose levels before
timeFrame: Blood glucose levels are going to be recorded before the start of the exercise protocol
measure: Blood glucose levels after
timeFrame: Blood glucose levels are going to be recorded immediately after the end of the exercise protocol
measure: Blood lactate levels after
timeFrame: Blood lactate levels are going to be recorded immediately after the end of the exercise protocol
Other outcomes:
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