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.
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.
Study Type
OBSERVATIONAL
Enrollment
31
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.
Maximal Expiratory Pressure (MEP)
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).
Time frame: 2 hours
Maximal Inspiratory Pressure (MIP)
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).
Time frame: 2 hour
Reactive Visuomotor Reaction Time
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).
Time frame: 2 hours
Dynamic Postural Stability (Y-Balance Test)
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.
Time frame: 2 hours
Static Core Stabilization Endurance (Prone Plank Test)
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).
Time frame: 2 hours
Forced Vital Capacity (FVC)
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%).
Time frame: 2 hours
Forced Expiratory Volume in 1 Second (FEV1%)
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%).
Time frame: 2 hours
Peak Expiratory Flow (PEF)
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%).
Time frame: 2 hours
Dynamic Abdominal Endurance (60-Second Sit-Up Test)
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.
Time frame: 2 hours
Change-of-Direction Speed and Agility (T-Drill Test)
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).
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Time frame: 2 hours