Inspiratory Muscle Training in Amateur CrossFit® Athletes

NCT ID: NCT06807957

Last Updated: 2026-01-27

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 94 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2026-01-31
• Study Completion Date: 2027-03-30

Brief Summary

The aim of this randomized controlled trial is to investigate the effectiveness of inspiratory muscle training (IMT) on the performance of athletes in CrossFit® activities, respiratory muscle strength, and perceived post-training fatigue. This study follows a two-arm randomized controlled trial protocol. Ninety-four volunteers aged between 18 and 60 years, enrolled in CrossFit® training, will be randomly allocated to the IMT Group, which involves respiratory training using a linear load device (Powerbreathe®) in conjunction with CrossFit® training; or the Non-IMT Group, which undergoes the same training as the intervention group but uses a device without a valve that ensures resistance. The primary outcome is to investigate the effectiveness of IMT: on maximum inspiratory pressure and maximum expiratory pressure. The secondary outcomes include performance in the six-minute walk test, Pistol, Burpee, Sit-up, Box Jump, Thruster, and Single-Under, burning 25 calories on the "Air Bike" measured by the time taken to reach the 25-calorie mark on this equipment, as well as the assessment of subjective fatigue perception. All outcomes of interest will be collected at baseline and reassessed: mid-term (8 weeks after allocation); and long-term (12 weeks after allocation), the IMT and MEP will be reassessed. Analyses will follow the intention-to-treat principle. Treatment effects will be assessed using Linear Mixed Models. The results of this study may help clarify the effects of IMT on CrossFit® athletes.

Detailed Description

Study design: This is a prospective randomized controlled trial with two arms. The study was registered with the Research Ethics Committee of the Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM): 81443024.9.0000.5108. Procedures and data collection: Participants who seek the CrossFit® service and enroll, as well as those who are already enrolled, will be invited to participate in this study. All eligible participants will receive information about the study and must sign an informed consent form before participating. The initial assessment and reassessment of the participant will take place at Academia Compasso Sete Lagoas (Boa Vista Unit and/or Centro Unit). The data collected will be: age, height, weight, body mass (BM), Body Mass Index (BMI), heart rate, blood pressure, gender, smoking history (yes/no), medications in use, time practicing the sport and the presence of any comorbidities. All outcomes of interest (respiratory muscle strength, subjective perception of fatigue and results obtained in CrossFit® exercises) will be collected at baseline and reassessed at the following time points: medium term (8 weeks after allocation) and long term (12 weeks after allocation), in an assessment room at the gym. The collected data will initially be entered into a standardized data collection form and then transferred to an Excel table.

The evaluation process will be divided as follows: first, the participant will complete the evaluation form, and then their MIP and MEP values will be collected. Next, the first evaluation test will be performed: "Air Bike" (25 calories); then the evaluation sequence will be performed: Sit-up, Pistol, Burpee, Box Jump, 6MWT, Thruster, and Single-Under. Additionally, after completing all the exercises on the second day of evaluation, the Borg Scale will be administered.

The randomization sequence for the experimental and control groups, with an allocation ratio of 1:1, will be generated by a computer program by one of the researchers who will not be involved in the recruitment of participants. The groups will be coded and the allocation will be transferred to a series of sealed and sequentially numbered opaque envelopes. Two evaluators participated in this stage of the research: researcher 1 will be responsible for the evaluations; and researcher 2 for randomization and distribution of equipment.

Group with TMI: CrossFit® training: participants will be guided and encouraged to attend at least 5 days of training. TMI: the device used for the intervention will be the POWERbreathe®. The load used will be 50% of MIP. The TMI will be performed in two series of 30 breaths through the mouth through the mouthpiece connected to the POWERbreathe®, with a 1-minute interval between series.

Group without TMI: participants allocated to the "No TMI Group" will receive the same interventions as the "Group with TMI", but without the respiratory training included. In addition, they will also perform the TMI in a simulated manner.

Conditions

Healthy

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: SUPPORTIVE_CARE
• Blinding Strategy: QUADRUPLE

Study Groups

Group with IMT

CrossFit® Training: ParticipaIMT: The intervention will utilize the POWERbreathe® device. Participants will be provided with the device for home training. The model selected for this study is the POWERbreathe® Classic Medium Resistance (Fitness).

The load will be set at 50% of each participant's MIP, as determined during the assessment phase using a vacuum manometer. IMT will be performed in two sets of 30 breaths through a mouthpiece connected to the POWERbreathe®, with a one-minute rest between sets. Participants will complete the training five days per week at home over the course of eight weeks. Additionally, participants will monitor their adherence by completing a log sheet to mark training days. To ensure proper use and management of the device, each participant will receive individual training after randomization. At the end of the eight weeks, participants will return the equipment to the research team for cleaning and redistribution to another participant in the same group.

Group Type: EXPERIMENTAL

Group with IMT

Intervention Type: DEVICE

Group with IMT + CrossFit training

CrossFit® Training

Intervention Type: BEHAVIORAL

The training routine will occur seven days a week, with participants encouraged and motivated to attend at least five training sessions. CrossFit® classes will include: warm-up exercises, strength training (with a focus on Olympic weightlifting and free weights), strength endurance (body weight and external loads), aerobic capacity (across multiple domains), maximal aerobic power (across multiple domains), anaerobic capacity (across multiple domains), cool-down activities, and mobility exercises. Each training session will be designed and supervised by a team of certified physical educators.

Group without IMT

Group without IMT Participants allocated to the "No IMT Group" will receive the same interventions as the "IMT Group," except for respiratory training. These participants will continue attending CrossFit® training sessions at the gym. They will also perform a simulated IMT, using a device without the valve that generates resistance to the respiratory muscles.

Group Type: PLACEBO_COMPARATOR

CrossFit® Training

Intervention Type: BEHAVIORAL

The training routine will occur seven days a week, with participants encouraged and motivated to attend at least five training sessions. CrossFit® classes will include: warm-up exercises, strength training (with a focus on Olympic weightlifting and free weights), strength endurance (body weight and external loads), aerobic capacity (across multiple domains), maximal aerobic power (across multiple domains), anaerobic capacity (across multiple domains), cool-down activities, and mobility exercises. Each training session will be designed and supervised by a team of certified physical educators.

Interventions

Group with IMT

Group with IMT + CrossFit training

Intervention Type: DEVICE

CrossFit® Training

The training routine will occur seven days a week, with participants encouraged and motivated to attend at least five training sessions. CrossFit® classes will include: warm-up exercises, strength training (with a focus on Olympic weightlifting and free weights), strength endurance (body weight and external loads), aerobic capacity (across multiple domains), maximal aerobic power (across multiple domains), anaerobic capacity (across multiple domains), cool-down activities, and mobility exercises. Each training session will be designed and supervised by a team of certified physical educators.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• Age between 18 and 60 years;
• Be enrolled in a CrossFit® program;
• Be available to perform TMI at home 5 days a week.

Exclusion Criteria

• Have any musculoskeletal, cardiovascular and/or neurological condition that prevents CrossFit® and/or IMT from being performed;
• Be a smoker;
• Not sign the Termo de Consentimento Livre Esclarecido (TCLE);
• Be performing or have performed IMT using linear load equipment in the last month.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Federal University of the Valleys of Jequitinhonha and Mucuri

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Locations

Academia Compasso - Kapura

Sete Lagoas, Minas Gerais, Brazil

Site Status: RECRUITING

Countries

Brazil

Central Contacts

Diego M Xavier, PhD student

Role: CONTACT

diegomendesxav@gmail.com

+55 31 997106999

Murilo X Oliveira, Pdh

Role: CONTACT

murilo.xavier@ufvjm.edu.br

+55 38 9996-0002

Facility Contacts

Mariana P Oliveira, Phd

Role: primary

maripaulinoliveira@gmail.com

+55 31 8585-8588

Other Identifiers

81443024.9.0000.5108

Identifier Type: -

Identifier Source: org_study_id