Introduction: The dehydration is a very common problem that is often not identified. The pediatric population is more susceptible to dehydration due to its physiological characteristics. Proper hydration is crucial for health since any degree of dehydration causes a reduction in physical and mental work capacity, hence the importance of preventing it by considering the type of drink. There are multiple beverage options, including industrial oral electrolytes (OE), on the other hand, coconut water (CW) has been studied as a natural alternative beverage with characteristics that can help maintain a state of euhydration. Objective: To determine if AC has a greater effect on hydration status than OE in adolescents who perform physical exercise. Material and methods: RCT, double blind. 34 subjects aged 13.02 ± 1.08 years were selected, assigned to treatment with either OE (Electrolit®) or CW. They received a weekly physical exercise session (4 weeks). Hydration was personalized (ml x kilograms of weight) and hydration was evaluated by Urine Specific Gravity (USG), Total Body Water (TBW) by bioimpedance and changes in body mass. Results:

Sesion 1 CW: Euhydrated (12) Dehydrated (5); OE: Euhydrated (8) Dehydrated (9); p value=0,16

Sesion 2 CW: Euhydrated (12) Dehydrated (5); OE: Euhydrated (7) Dehydrated (10); p value=0,08

Sesion 3 CW: Euhydrated (13) Dehydrated (4); OE: Euhydrated (13) Dehydrated (4); p value=1,00

Sesion 4 CW: Euhydrated (16) Dehydrated (1); OE: Euhydrated (8) Dehydrated (9); p value=0,007*

Conclusion: AC and OE have the same effect on hydration levels in adolescents who perform physical exercise.

1. For current epidemiological reasons of Covid-19, an increase of 30% of losses has been considered already established in the sample size, giving a total of 22 participants per group (44 in total). For the same reason, two groups of 22 participants (11 experimental and 11 controls) will be divided in order to reduce the population and the risk of contagion, following the health protocols established by the institution mentioned in Annex 2. The type of randomization to be used in the study will be based on the assigned treatment (A / B) by the balanced block method. This method consists of assembling a series of blocks, made up of a certain number of cells, in which the different types of treatment are included. The number of blocks will be determined by the number of participants to be included and the number of cells that it has been decided to include in each block, so in the present study 12 blocks with four treatment cells will be placed, giving a total of 44 treatments to the same as the number of study subjects. Each block will contain in each cell one of the treatment alternatives and within each block there must be a balanced number of possible treatments. Treatments A and B will be written in blocks (22 with treatment A and 22 with treatment B). The randomization will be carried out by a person external to the study and the same person will be the one who will randomly assign the treatments in the blocks and the numbering of each block. They will be summoned to 12:00 noon on Monday or Tuesday only according to the group assigned to start with the collection of personal data (Annex 3) and a mental test called Psychological Characteristics related to Sports Performance (CPRD) (Annex 4) which will be applied by an expert in the area of psychology, in addition, if training is required for the application of the test, the main researcher will be trained to be able to perform it properly.

2. After taking personal data, hydrating drinks will be administered immediately before training (7 ml x kg of weight) 4 hours before. At 2:00 p.m., your corresponding hydrating drink (4 ml x kg of weight) will be administered again. Each participant will have a 600 ml graduated glass that will be granted by the researcher to keep track of the drink administered at the different times of each session.

3. Immediately afterwards, the anthropometry and urine sample will be taken. To record body mass, the protocol developed by the International Society for the Advancement of Kinanthropometry (ISAK) will be followed. The study subjects will be weighed in sports shorts and barefoot before starting physical exercise, having been told that, in the case of urinating or defecating, they should do so before the initial weigh-in. Simultaneously with taking the body mass, the% ACT will be determined by electrical bioimpedance. To record body mass and% of ACT water, the Tanita BC-533 bioimpedance scale will be used with a reliability of 97%, precision of 0.1kg and with a measuring range of 0-150kg.

4. Once the anthropometry and urine sample have been taken, a 200 ml dose will be administered immediately before exercise (10-15) min.

5. They will continue with the physical exercise protocol which will receive a physical exercise session per week (Tuesdays), with a duration of 1 hour and 15 minutes each session. The exercise sessions will be carried out in the Domingo Savio sports fields and will be taught by the principal investigator who has worked as a sports coach in the soccer area for 3 years, in addition to being trained for this purpose in the same institution where he was will carry out the study. Days prior to the start of the practical execution of the protocol, parents and selected students will be summoned to a meeting in order to explain the dynamics that will take place. The physical exercise sessions will consist of 4 parts:

   1. The first part of the workout will consist of a 10 minute warm-up and stretching to increase your basal HR and prepare the body for the next high intensity stages and prevent injuries in teens. The warm-up will have a break of 5 minutes and hydration of 2 ml x kg of weight.
   2. This second part will take place in 12 min of continuous jogging around the field at an average pace, aiming to do one lap every 1 minute 36 seconds, giving a total of 7 and a half laps to the soccer field (Cooper's Test). 8 min rest for the total recovery of energy systems and hydration of 2 ml x kg of weight.
   3. In the second part of the training, the adolescents must run from one line to another, twenty meters apart, at the pace set by a tape. This race pace will increase every minute. Subjects start the test at a speed of 8 km / hr, the first minute increases to 9 km / hr and thereafter, each minute increases the pace ½ km / hr. The test ends when they cannot keep up with the pace set (Test de course Navette). Approximate time 10 min with 8 min rest and hydration of 2 ml x kg of weight.
   4. In this last part of the training session, it is a type of exercise based on tabatas, which consists of performing 8 different exercises for 20 seconds per 10 seconds of rest to the rhythm of the marked music, giving a time of 4 minutes per tabata. .2 tabatas will be made with an intermediate rest of 3 min between each tabata and hydration of 2 ml x kg of weight.

6. At the end of this last stage of the training session, anthropometry and information collection will be taken where the percentage of weight change, body composition with bioimpedance will be determined before starting the final hydration, since if it is done at the In reverse, it is very likely that no one will come out in a state of dehydration. After the anthropometry, they will be administered the corresponding post-exercise hydration (1.5 ml x kg of weight) and the urine sample will be collected. In the event that a subject has not urinated due to dehydration, their sterilized bottle will be taken home and the head of research will be notified immediately for its proper conservation or transport.

   The calculation of the percentage of lost weight will be calculated using the following formula:% Weight Loss or Dehydration = [(Initial Weight - Final Weight) / Initial Weight] x 100.

7. As a final point, the data obtained before the exercise will be compared with the data obtained after the exercise, where the euhydration cut-off points will be analyzed to categorize the subject as dehydrated or euhydrated. An effective drink (CW or OE) will be considered when any 2 or more indicators (GEO, ACT or Body Mass) are consistent with the euhydration thresholds.

Inclusion Criteria:

• Students that belong to "Instituto Salesiano Fray Pedro de Gante".
• Those students who are 12 years old and under 18 years of age.
• The parent or guardian of the adolescent and the student himself must agree to participate and comply with the autographed authorization of the informed consent letter.
• The adolescent must be in good physical and mental health.

Exclusion Criteria:

• Adolescents who suffer from a chronic disease such as obesity, hypertension, DM, asthma, COPD, cancer, injuries or physical disabilities.
• That the adolescent is allergic to any component of the treatments.

Elimination criteria:

• Adolescents who do not complete physical training sessions.
• That the adolescent presents a serious sports injury (fracture or sprain) during any of the physical exercise sessions.
• That the adolescent decides to withdraw once the practical research stage has begun.

At the moment there is the hesitation to share the information until having preliminary results.

4 weeks

The adverse event that could have occurred in addition to finishing the exercise session dehydrated would be: sports injury.

Some variables that could affect hydration levels and that, for economic reasons or beyond the control of the researchers in charge, could not be controlled or included in the study. The weather was an environmental factor that could not be controlled due to the facilities where the study was conducted. The gold standard of hydration was not applied for reasons of practicality and economy, in addition, hydration levels change in a matter of minutes.

The hydrating drinks will be placed in containers labeled as treatments 1 and 2 by a person in charge external to the project, where neither study subjects nor the main researcher will know the type of drink they will be receiving because both will have the same or similar appearance and taste.