Effects of Inspiratory Training on Respiratory Function in Swimming

NCT07595341 | Enrolling By Invitation

• 2 other identifiers: 150120261552026Sponsor-Investigator
• Study Type: interventional
• Target: 34
• Locations: 1 country
• Sites: 1

Brief Summary

Introduction: The diaphragm is the primary inspiratory muscle and plays a key role in ventilation, trunk stability, and exercise efficiency. Its dysfunction is associated with early fatigue, increased respiratory work, and reduced performance. Inspiratory muscle training (IMT) has been shown to improve respiratory function and exercise tolerance. Swimming, due to its specific characteristics, imposes an additional demand on the respiratory muscles. Objective: To evaluate the effects of an IMT program on diaphragmatic function, respiratory variables, cardiorespiratory response, and performance in swimmers. Methods: A randomized, parallel, double-blind clinical trial with 34 swimmers. The experimental group will perform an 8-week IMT program with progressive loads, while the control group will use a sham device without resistance. Diaphragmatic function will be assessed using ultrasound (thickness and excursion), along with respiratory variables (MIP, FEV₁, MEP, FVC), cardiovascular variables (heart rate, HRV), metabolic variables (lactate), and performance (100 m test). Expected results: IMT is expected to improve diaphragmatic function, increase inspiratory muscle strength, enhance ventilatory efficiency, and reduce respiratory fatigue, leading to improvements in performance and physiological responses to exercise. Conclusion: IMT could be an effective strategy to enhance respiratory function and swimming performance. This study provides a novel approach by incorporating ultrasound assessment of the diaphragm in an aquatic exercise context.

Conditions

Swimming; Inspiratory Muscle Training; Inspiratory Muscle Strength

Keywords

sport performance; IMT; RPE

Outcome Measures

Primary Outcomes (3)

• Sport performance

  Total time and split times for completing 100 m freestyle.

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Maximal inspiratory pressure.

  Inspiratory variables: Inspiratory muscle strength was assessed by measuring MIP using the POWERbreathe Smart Adaptor device. The participant was seated and used a mouthpiece with a leak hole to minimize activation of the orofacial musculature. The procedure consisted of a maximal expiration to residual volume, followed by a maximal inspiration sustained against the device for at least 2 seconds. Three attempts were performed with rest periods of at least 1 minute, and the highest value was selected.

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Maximal espiratory pressure.

  Expiratory variables: Pulmonary function was assessed using forced spirometry, recording FEV₁, MEP, and FVC with the MIR Spirobank Oxi Portable Spirometer device. For a manoeuvre to be acceptable, the subject had to perform a maximal inspiration followed by a rapid and continuous forced expiration, without coughing during the first second and with a smooth flow-volume curve, without leaks. The expiration had to last at least 6 seconds or until a volume plateau was reached. Manoeuvres with interruptions, false efforts, or closed glottis were discarded. Three acceptable manoeuvres were performed, and results were considered valid when the two best FEV₁ and FVC values differed by less than 150 mL. If this variability criterion was not met, additional attempts were performed until reproducible results were obtained.

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

Secondary Outcomes (6)

• lactate

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Perceived exertion.

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Dysnea

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Heart rate.

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

• Diaphragmatic excursion

  This measurement will be carried out from the randomization process until 8 weeks after the start of the inspiratory training program.

Study Arms (2)

Inspiratory training

ACTIVE COMPARATOR

The experimental group will perform an eight-week home-based training program using the POWERbreathe EX1-MR device, individually calibrated according to MIP. Participants will complete 30 deep inspirations per session, twice daily, seven days per week, with progressive intensities: 30% of initial MIP during weeks 1-2, 50% of the new MIP during weeks 3-4, 60% during weeks 5-6, and 70% of MIP during weeks 7-8, with the aim of familiarizing participants with the device and progressively adapting the diaphragm to increasing loads.

Device: Inspiratory training

Placebo

PLACEBO COMPARATOR

The control group will use the same device without resistance, maintaining the same breathing frequency and volume in order to control for the placebo effect.

Device: Placebo

Interventions

Placebo DEVICE

The control group will use the same device without resistance, maintaining the same breathing frequency and volume to control for the placebo effect.

Placebo

Inspiratory training DEVICE

The experimental group will perform an eight-week home-based training program using the POWERbreathe EX1-MR device, individually calibrated according to MIP. Participants will complete 30 deep inspirations per session, twice daily, seven days a week, with progressive intensities: 30% of initial MIP during weeks 1-2, 50% of the new MIP during weeks 3-4, 60% during weeks 5-6, and 70% of MIP during weeks 7-8, with the aim of familiarizing participants with the device and progressively adapting the diaphragm to increasing loads.

Inspiratory training

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Participants of both sexes, aged over 18 years.
• Minimum swimming training frequency of at least two sessions per week, with a minimum duration of 30 minutes per session, consistently maintained over the last three months.

You may not qualify if:

• Current or previous diagnosis of respiratory diseases.
• Musculoskeletal injuries limiting the ability to perform a 100-meter swimming test.
• Participation in inspiratory muscle training programs within the last six months.

Sponsors & Collaborators

• Universidad Rey Juan Carlos: lead

Study Sites (1)

Club de natación Moscardó

Madrid, Spain

Location

Study Officials

• Agustin c Velazquez

  Universidad Rey Juan Carlos

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: INVESTIGATOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: April 18, 2026
• First Posted: May 19, 2026
• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): January 1, 2027
• Last Updated: May 19, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share

Locations

ES (1)