Effects of Dehydration on Motor Skills, Attention, and Performance in Adolescent Football Players

The Invisible Threat in Football: Dehydration Impairs Motor Competence, Attention, and Technical Skills in Adolescent Football Players

This study aims to investigate how hydration status affects attention, motor competence, and football skills in adolescent male football players aged 13-14 years. Participants will complete standardized cognitive, motor, and sport-specific tests under two conditions: normal hydration (euhydration) and controlled dehydration (hypohydration). Hydration levels will be assessed using urine colour and body mass measurements, while attention and motor skills will be evaluated with validated tools. The study seeks to understand the impact of fluid balance on physical and cognitive performance in young athletes, without altering their usual routines.

Study Overview

• Status: Completed
• Conditions: Sport Performance; Hydration Status; Cognitive Function and Well-Being; Adolescent Athletic Performance; Football
• Intervention / Treatment: Behavioral: Euhydration Protocol; Behavioral: Hypohydration Protocol

Detailed Description

This comparative, quasi-randomised, counterbalanced, repeated-measures study investigates the effects of hydration status on cognitive function, motor competence, and football skills in adolescent male football players aged 13-14 years. A pilot study with 15 participants was conducted to determine effect size (Cohen's d = 0.43) and assess feasibility, confirming that a minimum of 73 participants would be required for the main study.

Seventy-five participants met strict inclusion criteria, including voluntary participation, no chronic or metabolic diseases, and a homogeneous sporting background. Participants had a mean age of 13 ± 1 years, height of 148 ± 5 cm, weight of 42 ± 5 kg, and BMI of 19.1 ± 1.2 kg/m². Most trained 8-10 hours per week and had 3-4 years of competitive football experience.

Each participant was tested under two hydration conditions: euhydration and hypohydration. In the euhydration condition, participants maintained regular fluid intake for 12 hours prior to testing and consumed 500 ml of water with a standardised breakfast. Hydration status was verified using first-morning urine samples and Armstrong's eight-point urine colour scale. In the hypohydration condition, participants underwent controlled fluid restriction and a treadmill walking protocol to achieve a 2-3% body mass loss. Pre- and post-exercise body weight and urine measurements were used to quantify hypohydration.

Following each testing session, participants completed the d2 Attention Test, the Bruininks-Oseretsky Test of Motor Proficiency - Short Form (BOT-2 SF), and a structured football skill test assessing passing, dribbling, and shooting accuracy. All procedures were performed under supervision in controlled environmental conditions, with scheduled rest intervals to prevent fatigue and ensure safety. Secondary checks included urine strip tests, while perceived exertion and local muscle discomfort were monitored continuously.

The study design allows for within-subject comparisons across hydration conditions to determine how fluid balance affects attention, motor skills, and sport-specific performance in adolescent athletes. Data will be analyzed to provide insights into the relationship between hydration and physical-cognitive performance in young football players, with implications for training and competition strategies.

• Study Type: Interventional
• Enrollment (Actual): 75
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Uşak
    • Uşak, Uşak, Turkey (Türkiye), 64200
      • Faculty of Sports Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Male sex (to avoid hormonal variability related to the menstrual cycle)
• Voluntary participation
• Age between 13 and 14 years
• Similar sporting background (regular football training and competition experience)
• No chronic or metabolic disease
• No respiratory or renal disease
• No medical condition requiring fluid restriction
• Not taking any medications or dietary supplements (e.g., vitamins, minerals, creatine, protein)
• No recent history of injury

Exclusion Criteria:

• Outside the specified age range
• Female sex
• Diagnosis of chronic/metabolic, respiratory, or renal disease
• Regular use of medication, diuretics, or dietary supplements (e.g., vitamins, - minerals, creatine, protein)
• Medical condition requiring fluid intake restriction
• Not engaged in sports or without a football background
• Recent injury history

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Euhydration Condition; Participants completed the euhydration condition first. They maintained habitual fluid intake for approximately 12 hours prior to testing, consuming 1.5-2.0 litres of water ad libitum during the day and night. On the morning of testing, a standardized breakfast was consumed along with 500 ml of water approximately two hours before testing. Participants were instructed not to urinate during the final 30 minutes prior to the session. Hydration status was verified using first-morning urine samples assessed via Armstrong's eight-point urine colour chart (target 1-2) and pre-test body mass measurements. Once classified as adequately hydrated, participants completed the d2 Attention Test, the Bruininks-Oseretsky Test of Motor Proficiency - Short Form (BOT-2 SF), and a structured football skill test. Attention and motor tests were conducted indoors, followed by the football skill test on an outdoor pitch. All testing was performed under supervision, with small participant groups to ensure st	Behavioral: Euhydration Protocol; Participants maintained their habitual fluid intake for 12 hours prior to testing, approximately 1.5-2.0 L ad libitum throughout the day and night, and consumed 500 mL of water with a standardized breakfast approximately two hours before the test. Participants were instructed to refrain from urinating during the 30 minutes preceding testing. Hydration status was verified using first-morning urine colour assessed on Armstrong's 8-point scale (target range 1-2) and pre-test body mass measurements. Cognitive, motor, and football skill performance were subsequently evaluated under these euhydrated conditions using the d2 Attention Test, BOT-2 SF, and a structured football skill test, respectively.; Other Names: Hydration Maintenance Protocol; Normal Hydration Condition
Experimental: Hypohydration Condition; After completing the euhydration condition and following a minimum 48-hour washout period, the same participants completed the hypohydration condition. Fluid intake was restricted beginning at 17:00 the day before testing, with no fluids overnight, and a low-fluid breakfast was provided on the morning of the session. Hypohydration was induced via a controlled treadmill walking protocol, with speed and duration individually adjusted to achieve 2-3% body mass loss. Participants were continuously monitored for heart rate, perceived exertion (Borg 6-20 scale), and localized muscle discomfort. Body mass was measured every 10 minutes, and fluid intake was not permitted during exercise. Hydration status was confirmed via pre- and post-exercise urine colour and body mass measurements, with urine strip tests as a secondary check. After a 15-minute seated recovery and consumption of low-water snacks, participants repeated the d2 Attention Test, BOT-2 SF, and football skill test under hypohydrat	Behavioral: Hypohydration Protocol; Participants underwent a hypohydration protocol beginning with fluid restriction from 17:00 on the day prior to testing, with no fluid consumption overnight, and a low-fluid breakfast on the morning of the session. Hypohydration was induced via supervised treadmill walking for approximately 45 ± 5 minutes at ~5.5 km/h with a 5% incline under moderate environmental conditions. No fluids were allowed during exercise, and body mass was measured every 10 minutes. Treadmill duration and intensity were individually adjusted until participants achieved a target body mass loss of 2-3%. Hydration status was confirmed via pre- and post-exercise urine colour and body mass measurements, with urine strip tests applied as a secondary verification. Following a 15-minute seated recovery period with consumption of low-water snacks, participants completed the d2 Attention Test, BOT-2 SF, and football skill test under hypohydrated conditions. Safety was continuously monitored via heart rate, Borg RPE sca; Other Names: Fluid Restriction + Exercise-Induced Dehydration Protocol

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body Mass Index (BMI)	Body mass index (BMI) was calculated using height and body weight measurements obtained at baseline. Height was measured once at baseline using a standard stadiometer, and body weight was measured immediately prior to any exercise or fluid manipulation using a calibrated scale with ±50 g precision (InBody 120). BMI was calculated as body weight (kg) divided by height squared (m²).	Baseline (single assessment during one laboratory visit prior to any exercise or hydration manipulation)
Hydration status assessed using urine color	Hydration status was assessed using first-morning urine samples (50-60 mL) collected prior to exercise and immediately following the exercise-induced dehydration protocol. Urine samples were analyzed using Armstrong's eight-point urine color chart. Urine color values of 1-2 indicated euhydration, whereas values of 5-6 indicated moderate hypohydration.	Baseline (first-morning urine sample) and immediately post-exercise (within 5 minutes after completion of treadmill exercise), assessed during a single test day
Hydration Status via Body Mass Loss	Exercise-induced body mass loss was used as an objective indicator of hydration status. Body weight was measured immediately before exercise and again within 5 minutes after completion of the treadmill protocol. Percentage hypohydration was calculated as the percentage change in body mass relative to baseline body weight. A body mass loss of 2-3% was considered indicative of significant hypohydration.	Baseline (pre-exercise body weight) and immediately post-exercise (within 5 minutes after completion of treadmill exercise), assessed during a single laboratory visit
Perceived Exertion and Muscle Discomfort	Perceived exertion was assessed using Borg's 6-20 Rating of Perceived Exertion (RPE) scale, and localized muscle discomfort was monitored through direct observation, particularly in the lower limbs. Ratings were recorded at regular 10-minute intervals during the treadmill protocol to ensure participant safety and to monitor subjective fatigue.	From start of treadmill exercise until completion of the exercise protocol (up to 60 minutes), assessed during a single laboratory visit

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
d2 Attention Test	Selective attention, processing speed, concentration, and attentional stability were assessed using the d2 Attention Test. Primary outcome parameters included total number of items processed (TN), error percentage (%E), concentration performance (CP), fluctuation rate (FR), and net performance (TN-E).	Post-exercise recovery period, assessed once between 8 and 15 minutes after completion of treadmill exercise during a single test day
Bruininks-Oseretsky Test of Motor Proficiency - Short Form (BOT-2 SF)	Motor competence was assessed using the BOT-2 Short Form, evaluating fine motor skills, gross motor skills, and combined motor performance across eight subtests. The test is validated and reliable for children aged 13-14 years.	Post-exercise recovery period, assessed once between 15 and 30 minutes after completion of treadmill exercise during a single test day
Football Skill Test	Football-specific technical skills, including passing, dribbling, and shooting, were assessed using a standardized football skill test conducted on a pre-marked field. Performance was quantified using total task completion time, with a one-second penalty applied for each technical error. Three trials were performed, and mean performance time was calculated.	Post-exercise recovery period, assessed once between 30 and 45 minutes after completion of treadmill exercise during a single test day

Collaborators and Investigators

• Sponsor: bekir tokay
• Collaborators: Uşak University
• Investigators: Study Chair: Mustafa AKIL, Professor Doctor, Uşak University, Department of Sports Science

Study record dates

Study Major Dates

• Study Start (Actual): January 23, 2025
• Primary Completion (Actual): January 23, 2025
• Study Completion (Actual): April 30, 2025

Study Registration Dates

• First Submitted: September 21, 2025
• First Submitted That Met QC Criteria: December 24, 2025
• First Posted (Actual): January 6, 2026

Study Record Updates

• Last Update Posted (Actual): January 6, 2026
• Last Update Submitted That Met QC Criteria: December 24, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Adolescents; Attention; Football; Technical Skills; Motor Competence; Hypohydration
• Other Study ID Numbers: 548-548-10

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No