The Effects of Intermittent Water Consumption and Restriction on Serum Electrolyte Levels in Professional Football Players During Competition

Background: In sports requiring intense physical exertion, particularly in endurance-based disciplines such as football, exercise-induced fluid and electrolyte losses can have adverse effects on thermoregulation, cardiovascular stability, and neuromuscular functions. Failure to balance these losses with adequate and timely rehydration increases the risk of performance decrement and injury. Although the literature indicates that intermittent and individualized fluid intake can mitigate these physiological effects, experimental studies conducted under field conditions with professional athletes remain limited. In this context, the purpose of this study is to evaluate the effects of intermittent water consumption administered during competition on exercise-induced changes in body weight and basic serum electrolyte levels (Na⁺, K⁺, Ca²⁺, Cl-) in professional football players.

Methods: Twenty-two male football players participated in the study and were randomly assigned to either the experimental (intermittent water intake, n=11) or control (ad libitum water intake, n=11) group. Both groups played a 90-minute match; body weight and serum electrolyte levels were measured before and after the competition. The experimental group was provided with a total of 10 mL/kg of plain water, administered before the match and at half-time.

Study Overview

• Status: Completed
• Conditions: Intermittent Water Intake
• Intervention / Treatment: Dietary supplement: Intermittent Plain Water Intake

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Male professional football players.
• Actively playing for Anadolu Selçukspor in the Turkish Football Federation 2nd League.
• Training at a professional level.
• Having no reported health problems.
• Voluntary participation in the study.
• Providing written informed consent.

Exclusion Criteria:

• Having any health problem that could affect participation in the football match or study measurements.
• Having an injury or medical condition preventing participation in exercise.
• Refusal to participate or failure to provide written informed consent.
• Not completing the match protocol or pre- and post-competition measurements.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Intermittent Water Intake Group; Participants in this arm received intermittent plain water intake during the football match. The total water volume was calculated according to body weight as 2 × 5 mL/kg and was administered in two equal doses: 15 minutes before the match and immediately after the first half.	Dietary supplement: Intermittent Plain Water Intake; Participants in the experimental group received plain water according to body weight. The total amount was calculated as 2 × 5 mL/kg and was administered in two equal doses: 15 minutes before the start of the football match and immediately after the first half. Water intake was directly observed and recorded.; Other Names: Hydration Protocol
No Intervention: Ad Libitum Water Intake Group; Participants in this arm received no specific hydration guidance during the study and followed their natural thirst-driven drinking behavior throughout the football match.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Serum Electrolyte Levels	Change in serum sodium, potassium, calcium, and chloride levels from before to after the 90-minute football match. Venous blood samples were collected before and immediately after the competition to evaluate exercise-induced changes in serum electrolyte balance.	Before and immediately after the 90-minute football match

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Body Weight	Change in body weight from before to after the 90-minute football match. Body weight was measured before and after the competition to estimate exercise-induced fluid loss.	Before and immediately after the 90-minute football match

Collaborators and Investigators

• Sponsor: Selcuk University
• Investigators: Principal Investigator: Süleyman Patlar, Prod. Dr., Selcuk University

Study record dates

Study Major Dates

• Study Start (Actual): January 10, 2016
• Primary Completion (Actual): January 25, 2016
• Study Completion (Actual): January 25, 2016

Study Registration Dates

• First Submitted: July 9, 2026
• First Submitted That Met QC Criteria: July 16, 2026
• First Posted (Actual): July 17, 2026

Study Record Updates

• Last Update Posted (Actual): July 17, 2026
• Last Update Submitted That Met QC Criteria: July 16, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Intermittent water intake; Professional football players; Serum electrolytes; Hydration strategy
• Other Study ID Numbers: SU-FSS-2015-41

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data that support the findings of this study will be made available from the corresponding author upon reasonable request.
• IPD Sharing Time Frame: Data will be available after publication and will remain available upon reasonable request.
• IPD Sharing Access Criteria: Data will be shared with researchers who provide a methodologically sound proposal and use the data for academic and scientific purposes. Requests should be directed to the corresponding author.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

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