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NCT Number: NCT07617116

Respiratory Function and Athletic Performance in Professional Soccer Players

This prospective observational study aims to investigate the relationship between respiratory function and multidimensional athletic performance parameters in professional soccer players. The primary hypothesis of the study is that soccer players with enhanced respiratory function and superior respiratory muscle strength will exhibit optimized motor performance outcomes and shorter (faster) reactive reaction times. Investigators will evaluate respiratory muscle strength, spirometric pulmonary functions, dynamic balance, core and abdominal endurance, and reactive visuomotor reaction times during a single testing session within the competitive season.

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Key information

Conditions

Respiratory Function Athletic Performance Pathologic Processes Pathological Conditions, Signs and Symptoms Reaction Time Respiration Disorders Respiratory Aspiration Respiratory Muscle Strength Respiratory Tract Diseases

Age range

18 year–35 year

Sex eligibility

Male

Study type

Observational

About this study

Professional soccer players from Istanbulspor A.S. Football Club will be screened and enrolled based on strict eligibility criteria. Eligible athletes will undergo a comprehensive, single-session testing protocol designed to prevent fatigue-related bias. Testing will commence with a baseline pulmonary function assessment and respiratory muscle strength evaluation (maximal inspiratory pressure [MIP] and maximal expiratory pressure [MEP]). Following a standardized rest interval, dynamic balance will be quantified using the Y-Balance Test (YBT). Subsequently, reactive visuomotor reaction times will be measured using the wireless BlazePod LED system. Finally, participants will execute higher-intensity, sport-specific performance assessments, including the isometric plank test for core endurance, a 60-second timed sit-up test for abdominal muscular endurance, and the T-drill test for agility. A standardized 10-minute seated rest interval will be strictly enforced between all physical assessments to ensure full physiological recovery. Bivariate correlation models will be utilized to analyze the direct relationships between respiratory indicators and performance indices.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Participants will be actively competing, licensed professional soccer players. -Participants will be engaged in regular, team-based training and competitive match schedules.
  • Participants will voluntarily provide written informed consent before any study-related physical performance assessments are conducted.

Exclusion criteria

  • Participants will be excluded if they present with an acute upper or lower respiratory tract infection that could potentially affect pulmonary function or maximal respiratory muscle performance.
  • Participants will be excluded if they have a documented history of major cardiothoracic surgery.
  • Participants will be excluded if they have any diagnosed respiratory and/or cardiovascular disorder associated with dyspnea or impaired pulmonary mechanics.
  • Participants will be excluded if they present with any condition that elevates clinical risk during maximal inspiratory and expiratory pressure assessments.
  • Participants will be excluded if they have sustained an acute musculoskeletal injury within the preceding 6 weeks that could compromise maximal physical exertion during sport-specific performance testing.

Treatment and study plan

Respiratory and Athletic Performance Assessments

Other

Participants will not receive any experimental clinical intervention as part of this observational study. Instead, they will undergo standard, non-invasive physiological and athletic performance screenings during their competitive season. These assessments will include digital respiratory pressure manometry to evaluate maximal inspiratory and expiratory pressures, computerized spirometry to measure pulmonary functions, the Y-Balance Test for dynamic postural stability, the BlazePod wireless LED system for reactive visuomotor reaction times, and sport-specific field tests (isometric plank, 60-second sit-up, and T-drill agility tests) to evaluate core endurance and agility. All measurements will be completed during a single testing session following standardized recovery intervals.

Primary outcomes

  1. Maximal Expiratory Pressure (MEP)

    Time frame: 2 hours

    Description: Respiratory muscle strength will be assessed using a portable digital respiratory pressure meter. Participants will execute a maximal expiratory maneuver from total lung capacity after full inspiration while wearing a nose clip. The highest reproducible value from at least three technically acceptable trials will be recorded in centimeters of water (cmH₂O).

  2. Maximal Inspiratory Pressure (MIP)

    Time frame: 2 hour

    Description: Respiratory muscle strength will be assessed using a portable digital respiratory pressure meter. Participants will perform a maximal inspiratory maneuver from residual volume following complete expiration while wearing a nose clip. The highest reproducible value from at least three technically acceptable trials will be recorded in centimeters of water (cmH₂O).

  3. Reactive Visuomotor Reaction Time

    Time frame: 2 hours

    Cognitive-motor reaction speed will be quantified using a wireless LED pod system arrayed in an equidistant semi-circular matrix. Participants will utilize their dominant lower limb to deactivate randomly illuminated pods as quickly as possible across 10 sets of 22 randomized stimuli. The mean reaction time across the challenge will be recorded in milliseconds (ms).

  4. Dynamic Postural Stability (Y-Balance Test)

    Time frame: 2 hours

    Functional reach capacity and dynamic balance will be quantified using a standardized Y-Balance Test apparatus. While maintaining a single-leg stance, participants will push indicator blocks in the anterior, posteromedial, and posterolateral directions. The maximum reach distance from three successful trials for each direction will be normalized to leg length and used to calculate a comprehensive Composite Score percentage (%) for both limbs.

  5. Static Core Stabilization Endurance (Prone Plank Test)

    Time frame: 2 hours

    Isometric core endurance will be quantified using the isometric prone plank test on a high-density mat. Participants will support their body weight exclusively on their forearms and toes, maintaining a strict neutral horizontal alignment of the head, spine, hips, and ankles. The test will be terminated when the participant voluntarily discontinues or fails to maintain correct alignment. Total duration will be recorded in seconds (sec).

Secondary outcomes

  1. Forced Vital Capacity (FVC)

    Time frame: 2 hours

    Pulmonary function will be evaluated using a computerized spirometry system in accordance with ATS/ERS guidelines. Participants will perform a maximal inspiratory effort followed by a rapid and forceful expiration sustained until complete exhalation. The highest reproducible value will be expressed both as an absolute volume in liters (L) and as a percentage of predicted reference values (FVC%).

  2. Forced Expiratory Volume in 1 Second (FEV1%)

    Time frame: 2 hours

    Pulmonary function will be evaluated using a computerized spirometry system in accordance with ATS/ERS guidelines. The volume of air exhaled during the first second of the FVC maneuver will be extracted. The highest reproducible value will be expressed both as an absolute volume in liters (L) and as a percentage of predicted reference values (FEV1%).

  3. Peak Expiratory Flow (PEF)

    Time frame: 2 hours

    Pulmonary function will be evaluated using a computerized spirometry system in accordance with ATS/ERS guidelines. The maximum flow rate achieved during the forced expiratory maneuver will be measured. The highest reproducible value will be expressed in liters per second (L/s) and as a percentage of predicted reference values (PEF%).

  4. Dynamic Abdominal Endurance (60-Second Sit-Up Test)

    Time frame: 2 hours

    Dynamic muscular endurance of the abdominal wall will be evaluated using a timed sit-up protocol. From a supine position with knees flexed at 90° and hands crossed over the chest, participants will flex the trunk until the elbows touch the knees, then return to the baseline position. The total number of correctly executed repetitions completed within exactly 1 minute (reps) will be recorded.

  5. Change-of-Direction Speed and Agility (T-Drill Test)

    Time frame: 2 hours

    On-field agility and change-of-direction speed will be quantified using a standardized T-configuration cone course monitored by electronic timing gates. Participants will perform forward sprinting, lateral side-shuffling, and backpedaling maneuvers through the course. The fastest completion time out of three successful trials will be recorded in seconds (sec).

Sponsors and collaborators

Lead sponsor

Istinye University

Other

Registry information

Official study title

Association Between Respiratory Function and Athletic Performance Parameters in Professional Soccer Players: A Cross-Sectional Study

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Jun 1, 2026
Registry last updated
Jun 1, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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