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

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.

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