An interventional study of IMT %40 MIP and IMT %50-60-70-80 in Respiratory Muscle Training, Inspiratory Muscle Strength and Maximal Oxygen Consumption, sponsored by Ondokuz Mayıs University. Completed at 1 site in Turkey (Türkiye). Open to male participants aged 18 Years to 30 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-21.
Sponsored by Ondokuz Mayıs University · Not applicable, Interventional, and Basic science
This study evaluated the effects of a 4-week respiratory muscle training (RMT) program using constant versus incremental threshold resistance on respiratory muscle strength, pulmonary function, extremity strength, and aerobic/anaerobic endurance in trained athletes. Participants were randomized into two groups: the Constant IMT group (trained at a fixed 40% of maximal inspiratory pressure [MIP]) and the Incremental IMT group (progressing weekly from 50% to 80% of MIP). Both groups trained twice daily, 5 days per week (2 sets of 30 breaths/day) for 4 weeks. Standardized physiological, spirometric, and athletic performance tests were assessed at baseline and post-intervention.
The purpose of this randomized, controlled trial was to compare the physiological and athletic performance adaptations induced by constant versus progressive-load inspiratory muscle training (IMT) in competitive athletes.
Inspiratory muscle fatigue can trigger the respiratory metaboreflex, causing sympathetic vasoconstriction in locomotor muscles and compromising exercise tolerance. Strengthening the inspiratory muscles is hypothesized to attenuate this reflex and improve limb muscular endurance and aerobic capacity.
Participants completed a 4-week intervention with a threshold inspiratory device (PowerBreathe).
Initial sessions were supervised in the exercise physiology laboratory, with remaining sessions performed under remote video monitoring. Outcomes were evaluated across multiple laboratory visits before and 48 hours following the 4-week protocol.
Ondokuz Mayıs University is the lead sponsor of 275 studies on the registry; 68 are open to participants now.
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Athletes performed fixed-resistance inspiratory muscle training using a PowerBreathe threshold device twice daily, 5 days per week for 4 weeks (2 sets of 30 repetitions/day) maintained at a constant 40% MIP throughout the intervention.
Device: IMT %40 MIP
Athletes performed progressive inspiratory muscle training using a PowerBreathe threshold device twice daily, 5 days per week for 4 weeks (2 sets of 30 repetitions/day). Resistance started at 50% MIP and increased weekly by 10% (50%, 60%, 70%, and 80% MIP).
Device: IMT %50-60-70-80
This study examined two inspiratory muscle training (IMT) protocols using the PowerBreathe device. Participants in both groups performed IMT twice daily, five days a week, for four weeks. Each session included 30 inspiratory breaths, totaling 60 breaths per day. The Constant IMT group trained with a fixed resistance of 40% MIP throughout the intervention. All participants received supervised instruction during the initial session. Subsequent sessions were home-based, monitored weekly through video submissions and participant check-ins. This design enables a structured comparison between progressive and constant loading in IMT for improving respiratory strength and endurance in trained athletes.
Also known as: The Constant IMT group trained with a fixed resistance of 40% MIP throughout the intervention.
This study examined two inspiratory muscle training (IMT) protocols using the PowerBreathe device. Participants in both groups performed IMT twice daily, five days a week, for four weeks. Each session included 30 inspiratory breaths, totaling 60 breaths per day. The Incremental IMT group began training at 50% of Maximal Inspiratory Pressure (MIP), with resistance increased weekly to 60%, 70%, and 80%. All participants received supervised instruction during the initial session. Subsequent sessions were home-based, monitored weekly through video submissions and participant check-ins. This design enables a structured comparison between progressive and constant loading in IMT for improving respiratory strength and endurance in trained athletes.
Also known as: The Incremental IMT group began training at 50% of Maximal Inspiratory Pressure (MIP), with resistance increased weekly to 60%, 70%, and 80%.
Change in maximal inspiratory pressure (MIP)
Maximal inspiratory pressure (MIP) will be measured using a device with a respiratory pressure measurement function and expressed in cmH2O. Change will be calculated as the Week 4 value minus the baseline value.
Time frame: Baseline and Week 4 (end of the intervention).
Change in Maximal Expiratory Pressure (MEP)
Maximal expiratory pressure was measured from total lung capacity against an occluded airway using a digital respiratory pressure meter (MicroRPM) and expressed in cmH2O. Change was calculated as Week 4 minus baseline.
Time frame: Baseline and Week 4 (end of the intervention).
Change in forced vital capacity (FVC)
Forced vital capacity (FVC) will be measured by spirometry and expressed in liters. Change will be calculated as the Week 4 value minus the baseline value.
Time frame: Baseline and Week 4 (end of the intervention).
Change in Forced Expiratory Volume in 1 Second (FEV1)
Volume exhaled in the first second of a forced exhalation maneuver was measured using spirometry, expressed in liters (L).
Time frame: Baseline and Week 4 (end of the intervention).
Change in FEV1/FVC Ratio
The ratio of forced expiratory volume in 1 second to forced vital capacity was assessed using spirometry, expressed as a percentage (%).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Slow Vital Capacity (SVC)
Vital capacity measured during relaxed, unforced breathing using spirometry, expressed in liters (L).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Maximal Voluntary Ventilation (MVV)
Maximal volume of air ventilated over a 12-second sprint breathing protocol was extrapolated to liters per minute (L/min).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Seated Medicine Ball Throw Distance
Upper body explosive power was measured by throwing a 3 kg medicine ball overhead from a seated position with the back supported against a wall. The maximum distance achieved across three trials was recorded in centimeters (cm).
Time frame: Baseline and Week 4 (end of the intervention).
Change in 30-Second Modified Push-Up Repetitions
Upper body muscular endurance was evaluated by counting the maximum number of correctly executed push-up repetitions performed within 30 seconds.
Time frame: Baseline and Week 4 (end of the intervention).
Change in 1-Minute Sit-Up Repetitions
Abdominal muscular endurance was evaluated by recording the maximum number of correctly executed sit-up repetitions completed in 60 seconds.
Time frame: Baseline and Week 4 (end of the intervention).
Change in 1-Repetition Maximum (1RM) Bench Press Strength
Maximal upper body dynamic strength was assessed via 1RM barbell bench press test protocol, expressed in kilograms (kg).
Time frame: Baseline and Week 4 (end of the intervention).
Change in 1-Repetition Maximum (1RM) Back Squat Strength
Maximal lower body dynamic strength was determined using a standard 1RM barbell back squat protocol, expressed in kilograms (kg).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Isometric Hand Grip Strength
Isometric hand grip strength was assessed using a Takei hand dynamometer for dominant and non-dominant hands, recorded in kilograms (kg).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Isometric Back and Leg Strength
Isometric back and leg strength were evaluated using a Takei digital back-and-leg dynamometer, recorded in kilograms (kg).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Vertical Jump Height
Explosive lower extremity power was evaluated via vertical jump test using a jump meter (KK 5406 Jumpmeter). The best attempt was recorded in centimeters (cm).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Single Leg Hop Performance and Limb Symmetry Index
Functional lower extremity performance was measured using single-leg hop test protocols (single hop, triple hop, crossover hop, and side hop). Maximum distance was recorded in cm, and the Limb Symmetry Index (LSI, %) was calculated.
Time frame: Baseline and Week 4 (end of the intervention).
Change in Anaerobic Peak and Mean Power (Wingate Test)
Anaerobic power was evaluated using a 30-second all-out Wingate test on a Monark 894E cycle ergometer against a resistance of 7.5% body weight, expressed in Watts (W).
Time frame: Baseline and Week 4 (end of the intervention).
Change in Estimated Maximal Oxygen Consumption (VO2max)
Aerobic capacity was evaluated using the Bruce Treadmill Test protocol. The test began on a motorized treadmill at 2.74 km/h and a 10% incline, with speed and incline increasing every 3 minutes until volitional exhaustion. Total test duration (T, in minutes) was recorded, and VO2max was estimated using the standardized regression equation: VO2max = 14.8 - (1.379 \* T) + (0.451 \* T\^2) - (0.012 \* T\^3), expressed in mL/kg/min. Change was calculated as Week 4 minus baseline.
Time frame: Baseline and Week 4 (end of the intervention) .
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Ran from Sep 2024 to primary completion in Nov 2024, 1 month.
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