The Effect of Inspiratory Muscle Training on Respiratory Parameters, Balance, Trunk Endurance and Trunk Isokinetic Muscle Strength in Wrestling Athletes

This study aims to investigate the multifaceted effects of inspiratory muscle training (IMT) on performance parameters in elite female freestyle wrestlers within the field of cardiopulmonary physiotherapy and rehabilitation. Unlike most studies in the sports physiotherapy literature, this research goes beyond respiratory parameters to include key functional outcomes such as balance, trunk endurance, and isokinetic trunk muscle strength.

Scientific Background and Rationale Freestyle wrestling is a physically demanding sport that requires simultaneous, dynamic use of both upper and lower extremities, along with high levels of strength, balance, and coordination. Success in competition is closely linked to factors such as postural stability, core muscle activation, and the ability to generate isometric and dynamic force. However, the contribution of respiratory muscles to athletic performance has often been overlooked or assessed only indirectly in previous studies.

Given the high-intensity and short-duration nature of wrestling matches, increased ventilatory demand places a significant burden on the diaphragm and accessory respiratory muscles. Recent evidence suggests that IMT not only improves pulmonary function but also enhances core stabilization and postural control. Therefore, directly assessing the effects of IMT on respiratory and trunk muscle performance in elite female wrestlers addresses a notable gap in the literature.

Study Design This is a randomized controlled experimental study involving 30 elite female freestyle wrestlers affiliated with the Turkish Olympic Preparation Center (TOHM-Trabzon). Participants will be randomly assigned into two groups (n=15 each) via simple randomization.

The intervention group will undergo IMT using the POWERbreathe Plus device, 5 days per week for 4 weeks. Training will begin at 50% of the participants' MIP and increase by 10% each week, reaching 80% by the final week.

The control group will receive placebo IMT at a constant load equivalent to 15% of baseline MIP, following the same training schedule.

All interventions will be delivered in addition to the athletes' regular training programs. Pre- and post-intervention assessments will be conducted by a blinded physiotherapist who is not involved in the implementation of the training.

Assessment Parameters and Instruments To comprehensively evaluate the impact of IMT, objective and validated tools will be employed. Pulmonary function will be assessed using the Cosmed Pony FX device, measuring MIP, MEP, FEV1, FVC, and the FEV1/FVC ratio. Trunk endurance will be evaluated using the McGill Core Endurance protocol, which includes tests for trunk flexion, extension, and lateral plank. Muscle strength will be measured using the Isomed 2000 isokinetic dynamometer at a velocity of 60°/s to determine peak torque during trunk flexion and extension. Balance performance will be assessed with both the Y Balance Test (in anterior, posterolateral, and posteromedial directions) and the Flamingo Balance Test, which measures the ability to maintain single-leg stance. In addition, a participant tracking form will be used to record demographic information, training history, and attendance. All assessments will be performed under standardized conditions by a blinded evaluator.

Statistical Methods Appropriate statistical methods will be employed to analyze the data. Distribution characteristics and group comparisons will be assessed accordingly. Intra-group and inter-group differences, as well as time-by-group interactions, will be analyzed. Effect sizes will be calculated using standard procedures, and statistical significance will be set at p \< 0.05.

Original Contribution of the Study This study is unique in its comprehensive evaluation of the effects of IMT not only on performance-related physical parameters but also on cardiopulmonary capacity in elite athletes. By focusing specifically on female wrestlers, the study contributes to sex-specific physiological research and is expected to provide evidence for the development of clinically applicable IMT protocols aimed at enhancing athletic performance and health.

• Time Held in Trunk Flexion Test [seconds] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Time Held in Side Plank Test [seconds] [Time frame: Baseline (Week 0) and post-intervention (Week 4)]
• Time Held in Trunk Extension Test [seconds] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Peak Torque of Trunk Flexors [Nm] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Peak Torque of Trunk Extensors [Nm] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Reach Distance in Y Balance Test - Anterior Direction [cm] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Reach Distance in Y Balance Test - Posteromedial Direction [cm] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Reach Distance in Y Balance Test - Posterolateral Direction [cm] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]
• Time Maintained in Flamingo Balance Test [seconds] [Time frame: Baseline (Week 0) and Post-intervention (Week 4)]