An interventional study of PrO2Fit Device in Exercise Induced Bronchospasm and Exercise Induced Asthma, sponsored by Indiana University. Completed at 1 site in United States. Open to participants aged 18 Years to 35 Years. Per ClinicalTrials.gov, last updated 2026-05-12.
Sponsored by Indiana University · Not applicable, Interventional, and Treatment
Due to the lack of studies examining the impact of inspiratory muscle training (IMT) on the severity of exercise-induced bronchoconstriction (EIB) and exercise performance, the specific aim of this study is to assess the efficacy of flow-resistive IMT on EIB severity and symptoms, short-acting beta-2-agonist medication use, operating lung volumes, respiratory and limb locomotor muscle deoxygenation during constant-load cycling exercise, exertional dyspnea, and cycling time-trial performance.
To the investigators knowledge, no study has been conducted assessing the impact of inspiratory muscle training (IMT) on exercise-induced bronchoconstriction (EIB) severity, exertional dyspnea, and cycling time-trial performance. A review noted that studies examining the impact of IMT on asthma have all demonstrated an increase in inspiratory muscle strength (maximal inspiratory pressure, MIP) and endurance (sustained maximal inspiratory pressure). In addition, it has been observed that the reduction in the perception of dyspnea following and during exercise leads to a reduction in short-acting beta-2-agonist (SABA) use and fewer asthma symptoms. The same review also noted the lack of data available to explain the impacts of IMT on exercise performance and tolerance in athletes with EIB. Due to the lack of studies examining the impact of IMT on the severity of EIB and exercise performance, the specific aim of this study is to assess the efficacy of flow-resistive IMT on EIB severity and symptoms, SABA medication use, operating lung volumes, respiratory and limb locomotor muscle deoxygenation during constant-load cycling exercise, femoral blood flow, exertional dyspnea, and cycling time-trial performance. It is hypothesized that eight weeks of IMT will reduce EIB's severity and symptoms, respiratory and limb locomotor muscle deoxygenation, improve operating lung volumes, and exertional dyspnea and improve cycling time-trial performance.
52 studies on the registry are indexed under Asthma, Exercise-Induced; 3 are open to participants now.
This study's enrollment of 15 is below the median of 47 across 40 interventional studies indexed under Asthma, Exercise-Induced.
Browse Asthma, Exercise-Induced studies →Indiana University is the lead sponsor of 986 studies on the registry; 198 are open to participants now.
Of its 148 completed or terminated interventional studies of FDA-regulated products, 118 (80%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FEV1
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The test protocol requires participants to inhale maximally (maximum inspiratory pressure, MIP) against 2mm diameter leak and sustain inhalation (sustained maximal inspiratory pressure, SMIP) until task failure. Participants will complete 3 SMIP maneuvers with each training session and use the best of the three for that day's training template (corresponding to about 80% SMIP for the IMT group) via the PrO2Fit software. Participants must match or exceed the SMIP template with each increasing level of the work-rest ratio. Work at each level consists of 6 breaths, 36 breaths total. If six breaths are completed, the next level starts. Rest intervals will progressively shorten as training continues from 40-seconds to 5-seconds. The session will be terminated if participants are unable to match at least 90% of the training template for two consecutive breaths or have completed all 36 breaths. Training will be done 3 times a week, and over 8-weeks.
Device: PrO2Fit Device
Similar to the IMT group protocol, participants will be required to complete 3 SMIP maneuvers with each training session. Participants will use the best of the three for that day's training template (corresponding to about 30% SMIP for the Sham-IMT group) via the PrO2Fit software. Participants must match or exceed the SMIP template with each increasing level of the work-rest ratio. Work at each level consists of 6 breaths, 36 breaths total. If six breaths are completed, the next level starts. Rest intervals will progressively shorten as training continues from 40-seconds to 30-, 20-, 15-, 10-, and 5-seconds. The training session will be terminated if participants are unable to match at least 90% of the training template for two consecutive breaths or have completed all 36 breaths. Training will be done 3 times a week, and over 8-weeks.
Device: PrO2Fit Device
The flow-resistive protocol using the device requires participants to maximally inhale as hard as they can and as long as they can against a small leak (2mm diameter hole) until task failure. This records maximum inspiratory pressure (MIP) and sustained maximal inspiratory pressure (SMIP) values which will be recorded and the best is chosen for the software template by the participant to continue their training session (previously described in arm/group description). The use of the device occurs three times a week, and used for 6-8 weeks.
Also known as: Flow-resistive inspiratory muscle training, Sham-Flow-resistive inspiratory muscle training
Exercise-Induced Bronchoconstriction (EIB) Severity
More specifically, the pre- and post-values of the percentage drop in forced expiratory volume in 1 second (FEV1) from the eucapnic voluntary hyperpnea (EVH) test before and after IMT will be measured. Percentage drop in forced expiratory volume in 1 second (FEV1) will be reported in percentages.
Time frame: 8 weeks
Maximum Inspiratory Pressure
More specifically, the pre- to post-values of maximum inspiratory pressure (reported as cmH2O) before and after IMT will be measured.
Time frame: 8 weeks
Sustained Maximum Inspiratory Pressure
More specifically, the pre- to post-values of sustained maximum inspiratory pressure (reported as pressure time units) before and after IMT will be measured.
Time frame: 8 weeks
16-km Cycling Time-Trial Time to Completion
More specifically, differences in 16-km cycling time-trial completion time (seconds) before and after IMT.
Time frame: 8 weeks
16-km Cycling Time-Trial Power Output
More specifically, differences in 16-km cycling time-trial power output (watts) before and after IMT.
Time frame: 8 weeks
Constant Load 1 and 2 Speed
More specifically, differences in constant load performance (i.e., speed) before and after IMT.
Time frame: 8 weeks
Perception of Breathing Intensity, Unpleasantness, and Leg Fatigue During Constant Load 1
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during constant load 1 (CL1) cycling. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
Time frame: 8 weeks
Perception of Breathing Intensity, Unpleasantness, and Leg Fatigue During Constant Load 2
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during constant load 2 (CL2) cycling. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
Time frame: 8 weeks
Perception of Breathing Intensity, Unpleasantness, and Leg Fatigue During Time-Trial Cycling
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during a 16-km cycling time-trial. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
Time frame: 8 weeks
Deoxygenation of the Respiratory and Limb Locomotor Muscles During Constant Load 1
More specifically, the effects of IMT on the deoxygenation (HHb) of the respiratory (RM) and limb locomotor muscles (LM) during constant load 1 (CL1) cycling
Time frame: 8 weeks
Deoxygenation of the Respiratory and Limb Locomotor Muscles During Constant Load 2
More specifically, the effects of IMT on the deoxygenation of the respiratory and limb locomotor muscles during constant load 2 (CL2) cycling
Time frame: 8 weeks
Deoxygenation of the Respiratory and Limb Locomotor Muscles During Time-Trial Cycling
More specifically, the effects of IMT on the deoxygenation of the respiratory and limb locomotor muscles during a 16-km cycling time-trial
Time frame: 8 weeks
Femoral Blood Flow of the Limb Locomotor Muscles During Constant Load 1
More specifically, the effects of IMT on femoral blood flow (FBF) of the limb locomotor muscles during constant load 1 (CL1) cycling
Time frame: 8 weeks
Femoral Blood Flow of the Limb Locomotor Muscles During Constant Load 2
More specifically, the effects of IMT on femoral blood flow (FBF) of the limb locomotor muscles during constant load 2 (CL2) cycling
Time frame: 8 weeks
Participants were recruited via flyers posted in the School of Public Health and distributed in Kinesiology labs (e.g., SPH-K409, SPH-K535) and other departmental courses. Flyers were also shared on the IU Classifieds website to reach the broader IU community. 15 participants enrolled; 11 completed the study. 4 withdrew or were excluded (EIB criteria not met or training noncompliance). Recruitment occurred from April 2022 to April 2025 at the School of Public Health.
| Milestone | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Started | 10 | 5 |
| Completed | 7 | 4 |
| Not completed | 3 | 1 |
| Withdrew: Lack of efficacy | 2 | 1 |
| Withdrew: Lost to follow-up | 1 | 0 |
More specifically, the pre- and post-values of the percentage drop in forced expiratory volume in 1 second (FEV1) from the eucapnic voluntary hyperpnea (EVH) test before and after IMT will be measured. Percentage drop in forced expiratory volume in 1 second (FEV1) will be reported in percentages.
| Percentage (%) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Exercise-Induced Bronchoconstriction (EIB) Severity | 19.84 ± 12.84 | 10.94 ± 8.94 |
More specifically, the pre- to post-values of maximum inspiratory pressure (reported as cmH2O) before and after IMT will be measured.
| cmH2O | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Maximum Inspiratory Pressure | 131.9 ± 33.1 | 122.4 ± 32.9 |
More specifically, the pre- to post-values of sustained maximum inspiratory pressure (reported as pressure time units) before and after IMT will be measured.
| ptu | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Sustained Maximum Inspiratory Pressure | 978.4 ± 216.8 | 978.8 ± 229.3 |
More specifically, differences in 16-km cycling time-trial completion time (seconds) before and after IMT.
| Seconds (sec) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| 16-km Cycling Time-Trial Time to Completion | 1900 ± 263 | 1668 ± 39 |
More specifically, differences in 16-km cycling time-trial power output (watts) before and after IMT.
| Watts (W) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| 16-km Cycling Time-Trial Power Output | 171.9 ± 57.4 | 221.8 ± 13.6 |
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during constant load 1 (CL1) cycling. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
| units on a scale | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - Dyspnea Intensity | 3.75 ± 1.61 | 3.94 ± 0.72 |
| Post-training - Dyspnea Intensity | 2.86 ± 1.61 | 3.25 ± 1.06 |
| Baseline - Dyspnea Unpleasantness | 3.25 ± 1.35 | 3.06 ± 1.11 |
| Post-training - Dyspnea Unpleasantness | 2.46 ± 1.60 | 2.50 ± 1.37 |
| Baseline - Leg Fatigue | 4.25 ± 2.23 | 4.31 ± 1.07 |
| Post-training - Leg Fatigue | 3.43 ± 1.22 | 3.81 ± 1.55 |
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during constant load 2 (CL2) cycling. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
| units on a scale | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - Dyspnea Intensity | 5.71 ± 2.60 | 7.06 ± 1.01 |
| Post-training - Dyspnea Intensity | 4.79 ± 2.70 | 5.17 ± 1.47 |
| Baseline - Dyspnea Unpleasantness | 5.13 ± 2.84 | 6.19 ± 1.66 |
| Post-training - Dyspnea Unpleasantness | 4.50 ± 2.74 | 4.60 ± 1.46 |
| Baseline - Leg Fatigue | 5.71 ± 2.27 | 7.06 ± 0.88 |
| Post-training - Leg Fatigue | 5.29 ± 2.45 | 5.69 ± 1.76 |
More specifically, whether IMT affects an individual's perception of exertional dyspnea (revised Borg Scales from 0-10 to rate breathing intensity and unpleasantness) and revised Borg Scales from 0-10 to rate leg fatigue during a 16-km cycling time-trial. Scores will be reported as whole numbers between 0-10. Higher scores indicate extreme intensity, unpleasantness, or fatigue.
| units on a scale | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - Dyspnea Intensity | 4.89 ± 2.26 | 5.75 ± 1.83 |
| Post-training - Dyspnea Intensity | 4.71 ± 2.19 | 5.38 ± 1.96 |
| Baseline - Dyspnea Unpleasantness | 4.50 ± 2.35 | 5.25 ± 2.25 |
| Post-training - Dyspnea Unpleasantness | 3.89 ± 2.45 | 4.31 ± 1.78 |
| Baseline - Leg Fatigue | 5.57 ± 1.94 | 6.56 ± 1.75 |
| Post-training - Leg Fatigue | 5.64 ± 2.17 | 6.63 ± 1.53 |
More specifically, the effects of IMT on the deoxygenation (HHb) of the respiratory (RM) and limb locomotor muscles (LM) during constant load 1 (CL1) cycling
| micromolar (uM) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - HHb LM | 5.50 ± 2.84 | 7.57 ± 10.62 |
| Post-training - HHb LM | 8.29 ± 6.24 | 13.62 ± 9.68 |
| Baseline - HHb RM | 6.19 ± 4.80 | 6.44 ± 2.35 |
| Post-training - HHb RM | 2.30 ± 4.39 | 5.45 ± 4.60 |
More specifically, the effects of IMT on the deoxygenation of the respiratory and limb locomotor muscles during constant load 2 (CL2) cycling
| micromolar (uM) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - HHb LM | 9.07 ± 4.05 | 17.49 ± 8.85 |
| Post-training - HHb LM | 10.58 ± 5.58 | 15.97 ± 8.55 |
| Baseline - HHb RM | 7.93 ± 3.40 | 12.19 ± 9.09 |
| Post-training - HHb RM | 6.87 ± 6.53 | 12.95 ± 8.11 |
More specifically, the effects of IMT on the deoxygenation of the respiratory and limb locomotor muscles during a 16-km cycling time-trial
| micromolar (uM) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - HHb LM | 10.58 ± 8.11 | 14.19 ± 9.54 |
| Post-training - HHb LM | 10.89 ± 7.43 | 13.25 ± 7.40 |
| Baseline - HHb RM | 6.40 ± 6.03 | 14.25 ± 5.43 |
| Post-training - HHb RM | 4.33 ± 5.63 | 8.94 ± 3.32 |
More specifically, the effects of IMT on femoral blood flow (FBF) of the limb locomotor muscles during constant load 1 (CL1) cycling
| millimeters per minute (mL/min) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - FBF | 9384.32 ± 5889.62 | 9055.95 ± 4048.40 |
| Post-training - FBF | 10255.24 ± 7543.17 | 11687.37 ± 3467.06 |
More specifically, the effects of IMT on femoral blood flow (FBF) of the limb locomotor muscles during constant load 2 (CL2) cycling
| milliliters per minute (mL/min) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Baseline - FBF | 14970.14 ± 6856.73 | 13760.42 ± 4047.17 |
| Post-training - FBF | 8608.25 ± 5294.61 | 15903.34 ± 9318.82 |
More specifically, differences in constant load performance (i.e., speed) before and after IMT.
| kilometers per hour (kph) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group |
|---|---|---|
| Constant Load 1 (15% Below GET) | 26.6 ± 7.0 | 35.9 ± 6.7 |
| Constant Load 2 (15% Above GET) | 25.8 ± 5.6 | 33.4 ± 9.9 |
Collected over from enrollment through end of study, up to 3 months. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Inspiratory Muscle Training (IMT) Group | 0/10 (0%) | 0/10 (0%) | 0/10 (0%) |
| Sham Inspiratory Muscle Training (Sham-IMT) Group | 0/5 (0%) | 0/5 (0%) | 0/5 (0%) |
After arm assignment, one participant ceased communication following emails indicating they were not training and did not respond to scheduling attempts; this individual was excluded. Two participants reported inconsistent training and subsequently stopped responding to follow-up communications and were excluded. One additional participant did not adhere to the prescribed training protocol and was excluded for noncompliance. This led to IMT = 7 and Sham-IMT = 4 for fully completed.
| Age, Customized(Years) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Age | 21.1 ± 2.2 | 21.2 ± 3.1 | 21.1 ± 2.4 |
| Sex: Female, Male(Participants) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Female | 0 | 0 | 0 |
| Male | 10 | 5 | 15 |
| Race and Ethnicity Not Collected(Participants) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Count of participants | — | — | 0 |
| EIB Severity(Percentage (%)) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Mean | 22.28 ± 13.67 | 18.74 ± 6.26 | 21.20 ± 11.59 |
| MIP(centimeters of water (cmH2O)) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Mean | 105.5 ± 32.1 | 94.8 ± 12.7 | 101.9 ± 27.2 |
| SMIP(pressure time units (ptu)) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Mean | 816.5 ± 208.1 | 781.6 ± 336.3 | 804.9 ± 245.9 |
| Constant Load 1 Speed(kilometers per hour (kph)) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Mean | 23.43 ± 9.89 | 30.73 ± 5.72 | 25.86 ± 9.21 |
| Constant Load 2 Speed(kilometers per hour (kph)) | Inspiratory Muscle Training (IMT) Group | Sham Inspiratory Muscle Training (Sham-IMT) Group | Total |
|---|---|---|---|
| Mean | 22.94 ± 7.91 | 28.03 ± 8.32 | 24.76 ± 8.14 |
2 further baseline measures are reported on the registry.
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: No — The plan to share individual participant data (IPD) is still unknown. However, if other researchers request IPD, we will evaluate that request and determine to share IPD.
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