Menthol Mouth Rinsing and Performance Responses of Elite Football Referees in the Heat

Menthol Mouth Rinsing and Performance Responses of Elite Football Referees in the Heat: a Randomized Crossover Trial

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.

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.