Trial Review

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR


Registration number
Help: Registration number
ACTRN12626001304325
Ethics application status
Help: Ethics application status
Approved
Date submitted
Help: Date submitted
25/05/2026
Date registered
Help: Date registered
29/10/2026
Date last updated
Help: Date last updated
29/10/2026
Date data sharing statement initially provided
Help: Data sharing statement date
29/10/2026
Type of registration
Help: Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of Diaphragmatic Fatigue Induced at Different Percentages of Maximal Inspiratory Pressure (MIP) on Turn Performance and Physiological Responses in Competitive Swimmers: A Pre–Post Experimental Study
Scientific title
Effect of diaphragmatic fatigue induced at different percentages of maximal inspiratory pressure on turn performance and physiological responses in competitive swimmers: a pre-post experimental study
Additional trial identifiers [1] 317384 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Related trial records

Health condition
Health condition(s) studied:
Inspiratory Muscle Fatigue 342045 0
Condition category
Condition code
Physical Medicine / Rehabilitation 338132 338132 0 0
Physiotherapy
Respiratory 338133 338133 0 0
Normal development and function of the respiratory system
Musculoskeletal 338134 338134 0 0
Normal musculoskeletal and cartilage development and function

Intervention/exposure
Study type
Interventional
Description of the intervention or exposure
One investigator conducts the sessions with the competitive swimmers, assessing baseline maximal inspiratory pressure (MIP) using a digital inspirometer. The participants are assigned to either the experimental group or the control group. All inspiratory procedures are performed using the POWERbreathe® handheld inspiratory muscle training device (a threshold loading apparatus designed to provide calibrated mechanical resistance during inhalation). Prior to data collection, all participants undergo a standardized 15-minutes education and training session led by the principal investigator. This familiarization includes instruction on correct diaphragmatic breathing technique (maximal inflation from residual volume to total lung capacity), proper insertion and seal of the silicone mouthpiece, and trial practice runs to ensure correct execution and minimize learning effects during testing.
Respiratory protocol: The resistive workload is set to 60% of the participant's predetermined MIP. The resistive workload is set to 60% of the participant's predetermined MIP. Participants perform continuous maximal inspiratory efforts against the load until volitional diaphragmatic fatigue, defined as the inability to complete 3 consecutive inspiratory efforts. The anticipated duration of this protocol is 5 to 10 minutes.
Participants perform continuous maximal inspiratory efforts against the load until volitional diaphragmatic fatigue, defined as the inability to complete 3 consecutive inspiratory efforts. The anticipated duration of this protocol is 5 to 10 minutes.
Immediately following the respiratory protocol, subjects perform a specific swimming task consisting of 3 underwater turns with 30 seconds of rest between repetitions. For each turn, subjects submerge at 7.5 meters pre-turn and remain fully submerged without breathing until reaching 15 meters post-turn. Checklists and digital logs are employed to ensure strict adherence to the breathing and swimming protocols.

Two inspiratory conditions will be applied according to the group assignment:

Experimental Group:
The experimental group undergoes an inspiratory muscle fatigue protocol. Subjects perform maximum consecutive inspiratory repetitions at a high-intensity workload corresponding to 60% of their predetermined MIP. The protocol continues dynamically until the subject reaches volitional fatigue, defined as the inability to successfully complete 3 consecutive inspiratory maneuvers.
Intervention code [1] 334175 0
Prevention
Description of the comparator or control
Individual Maximal Inspiratory Pressure (MIP) is measured at baseline using a digital pressure meter (MicroRPM®, CareFusion, Hoechberg, Germany).
Control participants perform the protocol using the same inspiratory threshold loading device (POWERbreathe KH2®). Low-Intensity Protocol & Duration: Participants perform a fixed sequence of 30 controlled inspiratory repetitions at a workload corresponding to 15% of their predetermined MIP. The anticipated duration of this low-intensity protocol is 3 to 5 minutes.
Immediately following the cessation of the respiratory protocol, participants perform the specific swimming task (3 consecutive turns with 30 seconds of passive rest between repetitions, maintaining strict apnea from 7.5 m pre-turn to 15 m post-turn)
Control group
Active

Outcomes
Primary outcome [1] 345525 0
Swim turn sprint performance 5-meter
Timepoint [1] 345525 0
Immediately post-intervention completion
Primary outcome [2] 345526 0
Swim turn sprint performance 10-meter
Timepoint [2] 345526 0
Immediately post-intervention completion
Secondary outcome [1] 462026 0
underwater dolphin kicks
Timepoint [1] 462026 0
Immediately post-intervention completion
Secondary outcome [2] 462028 0
Muscle Oxygen Saturation (SmO2)
Timepoint [2] 462028 0
Pre-intervention and Immediately post-intervention completion
Secondary outcome [3] 462029 0
Peripheral Oxygen Saturation (SpO2)
Timepoint [3] 462029 0
Pre-intervention and Immediately post-intervention completion
Secondary outcome [4] 462030 0
Countermovement Jump height (CMJ)
Timepoint [4] 462030 0
Pre-intervention and Immediately post-intervention completion
Secondary outcome [5] 462031 0
Maximal Inspiratory Pressure (MIP)
Timepoint [5] 462031 0
Pre-intervention and Immediately post-intervention completion
Secondary outcome [6] 462032 0
Total Hemoglobin
Timepoint [6] 462032 0
Pre-intervention and Immediately post-intervention completion

Eligibility
Key inclusion criteria
Competitive swimmers
Minimum age
15 Years
Maximum age
25 Years
Sex
Both males and females
Healthy volunteers
Yes
Key exclusion criteria
History of respiratory disease, asthma, or recent thoracic/abdominal injury.

Inability to complete the high-intensity respiratory protocol or achieve volitional fatigue.

Musculoskeletal injuries or pain within the last 6 months that could impair swimming turn performance or jump execution (CMJ).

Inability to maintain prolonged underwater immersion (apnea) from 7.5 meters pre-turn to 15 meters post-turn.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Central randomisation by computer software
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?


The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Statistical analysis was carried out using SPSS v.29 for Windows. Shapiro-Wilk test was used for assessing normality among variables. All variables were treated as non-normally distributed. Continuous data are presented as median and interquartile range (IQR). Categorical variables are presented as frequency and percentage. Between-group comparisons at baseline and for pre–post change scores were performed using the Mann–Whitney U test. Within-group pre–post changes were analysed using the Wilcoxon signed-rank test. For the three-repetition outcomes (underwater dolphin kicks, 5 m sprint time, and 10 m sprint time), within-group changes across repetitions were analysed using Friedman tests, and between-group comparisons were performed separately for each repetition and for the mean of the three repetitions using Mann–Whitney U tests. Effect sizes were reported as r for Mann–Whitney and Wilcoxon tests and Kendall’s W for Friedman tests. Statistical significance was set at p < 0.05.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
9/11/2026
Actual
Date of last participant enrolment
Anticipated
16/11/2026
Actual
Date of last data collection
Anticipated
16/11/2026
Actual
Sample size
Target
20
Accrual to date
Final
Recruitment outside Australia
Country [1] 28147 0
Spain
State/province [1] 28147 0
Madrid

Funding & Sponsors
Funding source category [1] 321958 0
University
Name [1] 321958 0
Universidad Europea de Madrid
Country [1] 321958 0
Spain
Primary sponsor type
University
Name
Universidad Europea de Madrid
Address
Country
Spain
Secondary sponsor category [1] 324832 0
None
Name [1] 324832 0
Address [1] 324832 0
Country [1] 324832 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 320494 0
comisión de investigación de la escuela de doctorado e investigación. Universidad Europea de Madrid
Ethics committee address [1] 320494 0
Ethics committee country [1] 320494 0
Spain
Date submitted for ethics approval [1] 320494 0
20/02/2026
Approval date [1] 320494 0
20/02/2026
Ethics approval number [1] 320494 0
2026-525

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 150654 0
Dr TRINIDAD MORALES- ALFONSO
Address 150654 0
Universidad europea de Madrid, Calle tajo sn, villaviciosa de odón, 28670, Madrid.
Country 150654 0
Spain
Phone 150654 0
+34605591205
Fax 150654 0
Email 150654 0
[email protected]
Contact person for public queries
Name 150655 0
TRINIDAD MORALES- ALFONSO
Address 150655 0
Universidad Europea de Madrid, Calle tajo sn, villaviciosa de odón, 28670, Madrid.
Country 150655 0
Spain
Phone 150655 0
+34605591205
Fax 150655 0
Email 150655 0
[email protected]
Contact person for scientific queries
Name 150656 0
TRINIDAD MORALES- ALFONSO
Address 150656 0
Universidad Europea de Madrid, Calle tajo sn, villaviciosa de odón, 28670, Madrid.
Country 150656 0
Spain
Phone 150656 0
+34605591205
Fax 150656 0
Email 150656 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
No


What supporting documents are/will be available?

No Supporting Document Provided


Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.