Effects of Core and Inspiratory Muscle Training on Muscle Oxygenation and Athletic Performance İn Young Soccer Players

Effects of Core and Inspiratory Muscle Training On Muscle Oxygenation and Athletic Performance İn Young Soccer Players

The purpose of this randomized controlled trial is to investigate the effects of core training and inspiratory muscle training (IMT) on muscle oxygenation and athletic performance in youth male soccer players aged 15-18. A total of 54 healthy soccer players will be included and randomly assigned into three equal groups: the Control Group, the Core Training Group, and the Core Training + IMT Group.

All interventions will be implemented for 8 weeks in addition to routine soccer training sessions. Assessments will be performed at baseline (Week 0), mid-intervention (Week 4), and post-intervention (Week 8). The primary outcome measures of the study are aerobic capacity assessed by the Yo-Yo Intermittent Recovery Test Level 1 and muscle oxygenation parameters monitored via near-infrared spectroscopy (NIRS) using a MOXY monitor. Secondary outcome measures include sprint performance, agility, dynamic balance, core muscle strength and endurance, inspiratory muscle strength, lower extremity explosive power, and soccer-specific technical performance tests.

Overall, this study aims to reveal the combined effects of core training and inspiratory muscle training on muscle oxygenation, respiratory functions, aerobic capacity, and soccer performance, while explaining the underlying physiological mechanisms in youth athletes.

Study Overview

• Status: Not yet recruiting
• Conditions: Athletic Performance; Respiratory Function; Muscle Oxygenation
• Intervention / Treatment: Behavioral: Core Training Program; Device: Inspiratory Muscle Training (IMT)

Detailed Description

Background:

Soccer performance is a multidimensional structure resulting from the interaction of technical, tactical, psychological, and physical components. In modern soccer, players frequently perform high-intensity running, sprinting, directional changes, and repeated efforts. Therefore, aerobic capacity, recovery ability, and the efficiency of muscle oxygen utilization are of critical importance.

Respiratory muscle fatigue during high-intensity exercise can limit performance by triggering the respiratory muscle metaboreflex, which reduces blood flow to peripheral muscles. Inspiratory muscle training (IMT) aims to attenuate these adverse effects by enhancing the strength and endurance of the diaphragm and auxiliary respiratory muscles. Similarly, core training improves trunk stability, enhances movement economy, optimizes force transfer along the kinetic chain, and contributes to athletic performance measures. Near-infrared spectroscopy (NIRS) is a non-invasive technology used to evaluate muscle oxygenation and hemodynamic responses during exercise. The MOXY monitor utilized in this study will allow real-time evaluation of muscle oxygen saturation (SmO2) and total hemoglobin (THb) levels.

Objectives:

The primary objective is to investigate the effects of core training and inspiratory muscle training on muscle oxygenation and aerobic performance in youth male soccer players. Secondary objectives are to examine changes in maximal inspiratory pressure, sprint performance, agility, dynamic balance, core strength/endurance, lower extremity explosive power, and soccer-specific technical skills.

Study Design & Interventions:

This study is designed as a three-arm, parallel-group, randomized controlled trial involving 54 healthy male soccer players. Participants will be randomly allocated into one of three groups:

1. Control Group: Continues routine soccer training only.
2. Core Training Group: Receives a structured core training program in addition to routine soccer training.
3. Core Training + IMT Group: Receives both the core training program and inspiratory muscle training in addition to routine soccer training.

The core training program will be implemented 3 days a week, lasting approximately 20-25 minutes prior to routine soccer practices. The program is structured on progressive overload principles, gradually increasing duration and difficulty. IMT will be performed 3 days a week using a threshold device. Participants will complete 2 sets of 30 breaths per session. Training intensity will start at 50% of maximal inspiratory pressure (MIP) and progress weekly up to approximately 70% MIP.

Assessments & Statistical Analysis:

All assessments will be conducted at baseline (Week 0), mid-intervention (Week 4), and post-intervention (Week 8). Primary outcomes include aerobic capacity (Yo-Yo IR1 distance) and muscle oxygenation parameters (SmO2, desaturation/reoxygenation rates, and THb). Secondary outcomes include 20-meter sprint (manual stopwatch), Illinois agility test, Y-Balance test, core strength/endurance tests, Standing Long Jump, MIP (cmH2O), Modified 10-Meter Dribbling Test, and the Wall Passing Accuracy Test. Linear mixed-effects models will be used to analyze group and time effects. Statistical significance will be set at p < 0.05.

• Study Type: Interventional
• Enrollment (Estimated): 54
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Abdurrahim Eyüp Canbaloglu, MSc; Phone Number: +90 5346492322; Email: abdurrahim.eyup@gmail.com

Study Locations

• Turkey (Türkiye)
  • Iğdır, Turkey (Türkiye), 76000
    • Igdir University
    • Contact: Abdurrahim Eyüp Canbaloglu, MSc; Phone Number: +90 5346492322; Email: abdurrahim.eyup@gmail.com
    • Contact: Dilek Cokar, Phd; Phone Number: +90 5343072752; Email: dilek.cokar@istinye.edu.tr
    • Principal Investigator: Abdurrahim Eyüp Canbaloglu, MSc

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Being between 15 and 18 years of age.
• Being a male soccer player.
• Actively and regularly participating in trainings at Alagöz Soccer Club.
• Having participated in regular soccer training for at least the last 6 months.
• Being able to continue routine trainings throughout the study period.
• Being fully informed about the research.
• Having obtained voluntary informed consent, and parental/guardian consent for participants under 18 years of age.
• Having the cognitive and physical capacity to understand and fulfill the specific test and exercise instructions.

Exclusion Criteria:

• Having a history of lower extremity, trunk-core, or athletic performance-limiting injury within the last 6 months.
• Having undergone orthopedic lower extremity or spine surgery within the last 1 year.
• Having active musculoskeletal pain or any orthopedic/neurological condition that prevents exercise.
• Having any health condition that prevents the safe execution of balance, sprint, agility, jump, or core endurance tests.
• Having asthma, chronic respiratory system diseases, exercise-induced bronchospasm, cardiovascular disease, or a physician-imposed restriction on high-intensity exercise that could affect respiratory muscle or exercise testing.
• Having open wounds, infections, or severe skin sensitivity that prevents the application of sensors placed on the skin.
• Currently participating in another structured respiratory muscle training or structured core exercise program that could affect the study results.
• Having a body mass index (BMI) of 30 kg/m² or above.
• Being deemed unsuitable for the study by the researcher due to safety concerns.
• Withdrawal from the study at the request of the participant or their parent/guardian.
• Missing two consecutive exercise sessions or having an insufficient overall attendance rate.
• Developing an exercise-preventing injury or illness during the study period.
• Occurrence of any safety risk during testing or exercise sessions.
• Non-compliance with the study protocol.
• Starting another additional exercise program during the study.
• Technical inability to obtain reliable measurement data.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control Group; Participants in this group will only continue their routine soccer training program for 8 weeks without any additional core or respiratory intervention.
Experimental: Core Training Group; Participants will perform a structured core training program in addition to their routine soccer training. The intervention will be conducted 3 days a week for 8 weeks, taking approximately 20-25 minutes before soccer practices, using a progressive overload principle.	Behavioral: Core Training Program; A structured, progressive core stability training program targeting trunk and abdominal musculature. The exercises will be conducted 3 days a week for 8 weeks, taking approximately 20-25 minutes before soccer practices.
Experimental: Combined Training Group; Participants will receive both the structured core training program and inspiratory muscle training (IMT) in addition to routine soccer training. Core training will be done 3 days a week for 20-25 minutes. IMT will be performed 3 days a week using a threshold device (2 sets of 30 breaths), starting at 50% of maximal inspiratory pressure (MIP) and progressing to 70% over 8 weeks.	Behavioral: Core Training Program; A structured, progressive core stability training program targeting trunk and abdominal musculature. The exercises will be conducted 3 days a week for 8 weeks, taking approximately 20-25 minutes before soccer practices.; Device: Inspiratory Muscle Training (IMT); Inspiratory muscle training performed using a threshold device. The protocol consists of 2 sets of 30 breaths per session, 3 days a week for 8 weeks. Training intensity starts at 50% of maximal inspiratory pressure (MIP) and progresses up to 70% MIP.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Aerobic Capacity	Assessed using the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) to determine the total distance covered in meters.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Muscle Oxygen Saturation (SmO2)	Measured in percentage (%) during exercise using near-infrared spectroscopy (NIRS) via a MOXY monitor to evaluate muscle oxygenation.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Total Hemoglobin (THb)	Measured in arbitrary units or micro-molar concentrations using a MOXY monitor (NIRS technology) to assess local blood volume changes and muscle hemodynamics.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
20-Meter Sprint Performance	Assessed using a 20-meter sprint test with a manual stopwatch to measure running speed in seconds.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Agility Performance	Measured using the Illinois Agility Test to evaluate the participant's ability to change direction quickly, recorded in seconds.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Dynamic Balance	Assessed using the Y-Balance Test (YBT) to measure dynamic balance and stability in anterior, posteromedial, and posterolateral directions, recorded in centimeters.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Core Muscle Strength and Endurance	Evaluated using core endurance tests (such as plank, side bridge, and trunk flexor/extensor endurance tests) to measure the holding time in seconds.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Lower Extremity Explosive Power	Measured using the Standing Long Jump test to evaluate horizontal explosive power, recorded in centimeters.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Maximal Inspiratory Pressure (MIP)	Measured using a digital respiratory pressure meter (or PowerBreathe device) to evaluate maximal inspiratory muscle strength, recorded in cmH2O.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Soccer-Specific Dribbling Performance	Assessed using the Modified 10-Meter Dribbling Test to measure soccer-specific ball control and speed, recorded in seconds.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)
Soccer Passing Accuracy	Measured using the Wall Passing Accuracy Test to evaluate soccer-specific technical passing precision, recorded as a total accuracy score.	Baseline (Week 0), Mid-intervention (Week 4), and Post-intervention (Week 8)

Collaborators and Investigators

• Sponsor: Istinye University
• Investigators: Principal Investigator: Abdurrahim Eyüp CANBALOĞLU, MSc, Igdir University

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: June 15, 2026
• First Submitted That Met QC Criteria: June 17, 2026
• First Posted (Actual): June 18, 2026

Study Record Updates

• Last Update Posted (Actual): June 18, 2026
• Last Update Submitted That Met QC Criteria: June 17, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Diaphragm; Inspiratory Muscle Training; Aerobic Capacity; Near-Infrared Spectroscopy; Core Training; Youth Soccer
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Respiration Disorders; Pathological Conditions, Signs and Symptoms; Respiratory Aspiration
• Other Study ID Numbers: 2026/78

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared with third parties to ensure the confidentiality and privacy of the participants, in accordance with the informed consent limitations and ethical committee guidelines.

Drug and device information, study documents

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