An interventional study of Sodium Citrate Oral Product and Placebo in Exercise-Induced Fatigue, Athletic Performance and Soccer, sponsored by Hacettepe University. Not yet recruiting. Open to female participants aged 18 Years to 25 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-30.
Sponsored by Hacettepe University · Not applicable, Interventional, and Basic science
The aim of this research is to determine whether sodium citrate supplementation, taken at the best individual time, would improve repeated sprint performance in professional female soccer players.
The main questions it aims to answer are:
This study is a randomized, double-blind, placebo-controlled crossover trial designed to investigate the effects of acute sodium citrate (SC) supplementation on repeated sprint performance and acid-base responses in female soccer players. Based on an a priori sample size calculation using G*Power (version 3.1), a minimum of 20 participants is required and will be recruited. Eligible participants will be professional female soccer players competing in the Turkish Women's Third League.
Each participant will complete two experimental trials in a randomized order, separated by a washout period of at least three days. During the SC trial, participants will ingest SC at a dose of 0.5 g·kg-¹ body mass dissolved in a flavored beverage. During the placebo (PL) trial, participants will consume a taste- and appearance-matched sodium chloride solution. Both supplements will be prepared by a researcher not involved in data collection to ensure allocation concealment and maintenance of double blinding.
On each experimental visit, participants will arrive at the laboratory following an overnight fast and will consume a standardized breakfast before supplementation. Capillary blood samples will be collected before supplementation and at regular intervals thereafter to determine blood bicarbonate concentration. During the SC condition, exercise testing will commence once blood bicarbonate concentration has increased by at least 5.0 mmol·L-¹ above baseline (individualized peak bicarbonate response; Tpeak). During the placebo condition, exercise testing will begin 120-150 minutes after ingestion, corresponding to the expected time window for peak bicarbonate responses observed during SC supplementation. To minimize the influence of hormonal fluctuations on exercise performance and physiological responses, both experimental trials will be conducted during the same phase of the menstrual cycle, outside the menstruation period. Participants using oral contraceptives will be excluded.
Repeated sprint performance will be assessed using the Running-based Anaerobic Sprint Test (RAST), which consists of six maximal 35-m sprints separated by 10 seconds of passive recovery. Sprint performance outcomes will include sprint times, peak power, minimum power, mean power, and fatigue index. Capillary blood samples will be collected at baseline, immediately before exercise, and immediately after exercise to determine blood bicarbonate concentration, blood pH, and lactate concentration. Ratings of perceived exertion (RPE) will be recorded after each sprint using the Borg 6-20 scale. The success of participant blinding will be evaluated using a blinding questionnaire administered at three predefined time points during the study.
Hacettepe University is the lead sponsor of 983 studies on the registry; 212 are open to participants now.
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Exclusion Criteria:
Participants will ingest sodium citrate at a dose of 0.5 g/kg body weight dissolved in flavored water. Capillary blood sampling will begin 90 minutes post-ingestion and continue at regular intervals. Exercise will begin when blood bicarbonate concentration reaches its individual peak (T\_peak).
Dietary Supplement: Sodium Citrate Oral Product
Participants will ingest sodium chloride (NaCl) at a taste-matched dose. Exercise will begin 120-150 minutes post-ingestion, consistent with the expected digestion timeline and the typical T\_peak window observed with sodium citrate supplementation.
Other: Placebo
0.5 g/kg body weight of sodium citrate dissolved in flavored water, ingested orally. Exercise begins at individual peak blood bicarbonate time (T\_peak), determined through serial capillary blood sampling starting 90 minutes post-ingestion.
Also known as: Trisodium citrate
Sodium chloride (NaCl) at a taste-matched dose dissolved in flavored water, ingested orally. Exercise begins 120-150 minutes post-ingestion.
Also known as: Sodium Chloride, NaCl
Minimum Power
The lowest power output recorded across six maximal 35-meter sprints during the Running-based Anaerobic Sprint Test (RAST). Calculated as body weight (kg) multiplied by the square of sprint distance (m) divided by the cube of the slowest sprint time (s).
Time frame: Measured during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
Fatigue Index
The rate of power decline across six maximal 35-meter sprints during the Running-based Anaerobic Sprint Test (RAST). Calculated as the difference between peak power and minimum power divided by total sprint time (W/s).
Time frame: Measured during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
Peak Power
The highest power output recorded across six maximal 35-meter sprints during the Running-based Anaerobic Sprint Test (RAST). Calculated as body weight (kg) multiplied by the square of sprint distance (m) divided by the cube of the fastest sprint time (s).
Time frame: Measured during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
Mean Power
The average power output recorded across six maximal 35-meter sprints during the Running-based Anaerobic Sprint Test (RAST). Calculated as the mean of all six individual sprint power values.
Time frame: Measured during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
Sprint Times
Individual sprint times recorded for each of the six maximal 35-meter sprints during the Running-based Anaerobic Sprint Test (RAST), measured in seconds using a photoelectric timing system.
Time frame: Measured during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
Blood Bicarbonate Concentration
Capillary blood bicarbonate concentration (HCO₃-, mmol/L) measured at baseline, pre-exercise, and post-exercise using a portable blood gas analyzer.
Time frame: Measured at baseline (pre-ingestion), pre-exercise (at T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo), and at 1, 3, 5, and 7 minutes post-exercise.
Blood pH
Capillary blood pH measured at baseline, pre-exercise, and post-exercise using a portable blood gas analyzer.
Time frame: Measured at baseline (pre-ingestion), pre-exercise (at T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo), and at 1, 3, 5, and 7 minutes post-exercise.
Blood Lactate Concentration
Capillary blood pH measured at baseline, pre-exercise, and post-exercise using a portable blood gas analyzer.
Time frame: Measured at baseline (pre-ingestion), pre-exercise (at T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo), and at 1, 3, 5, and 7 minutes post-exercise.
Rating of Perceived Exertion (RPE)
Perceived exertion rated by participants after each of the six maximal 35-meter sprints using the Borg RPE scale (6-20).
Time frame: Measured after each sprint during the RAST test, administered immediately after the individualized ingestion-to-exercise interval (T_peak for sodium citrate; 120-150 minutes post-ingestion for placebo)
No study locations are listed for this record.
Plan to share: No — Individual participant data will not be shared due to participant confidentiality and the absence of institutional data sharing infrastructure.
This study is not yet recruiting, as verified in Jul 2026. You cannot join it, but the record below documents what was studied.
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