Inspiratory Muscle Training Increases Inspiratory Pressures and May Improve Psychophysiological Outcomes in Young Adults

Inspiratory Muscle Training (IMT) is a targeted respiratory intervention designed to strengthen the diaphragm through resisted inhalation. While IMT has demonstrated clear physiological and psychological benefits in clinical and older adult populations, its effect on healthy young adults remains underexplored. We tested the hypothesis that a 6-week inspiratory muscle training (IMT) protocol would enhance both inspiratory muscle function and psychological well-being in healthy young adults. Eighteen healthy recreationally active young adults (males n = 10, females n = 8) without prior IMT experience were recruited and randomized into an experimental IMT group (n = 9) or a sham control group (n = 9). Using the POWERbreathe K5, participants completed 30 breaths per session, five days per week for six weeks at 70% of MIP (IMT group) or 17 cmH2O (sham group). Assessments were conducted prior to and following IMT or sham interventions. Physiological measures included a maximal oxygen uptake test (VO2max) and peak power output on a cycle ergometer via a ramp test, peak inspiratory pressure (S-Index), and peak inspiratory flow. Psychological outcomes included fatigue (Fatigue Severity Scale), perceived stress (Perceived Stress Scale), anxiety and depression (Hospital Anxiety and Depression Scale), and sleep quality (Pittsburgh Sleep Quality Index). At baseline, both groups reported moderate stress, non-clinical levels of fatigue, anxiety, and depression, and mild sleep difficulties. Following the intervention, the IMT group showed significant increases in S-Index (Pre-IMT: 120.17 ± 33, Post-IMT: 169.35 ± 24 cmH2O, p < 0.001), PIF (Pre-IMT: 6.65 ± 2, Post-IMT: 8.56 ± 1 L/s, p = 0.001), and peak power output at VO2 peak (Pre-IMT: 154.38 ± 46, Post-IMT: 173.35 ± 39 W, p = 0.017). No statistically significant changes were observed in VO2max in the IMT group (Pre: 35.79 ± 6, Post: 35.57 ± 4 ml/kg/min, p = 0.881) or the sham group (Pre: 39.12 ± 4, Post: 38.16 ± 3 ml/kg/min, p = 0.126). There were no significant between-group differences in psychological measures. However, favorable trends were observed in the IMT group, including reductions in stress (↓2.59%) and smaller increases in fatigue (↑6.01%) and depression (↑7.85%), compared to the sham group with greater increases in fatigue (↑14.62%) and depression (↑39.54%). Observed increases in psychological measures may be influenced by extraneous factors unrelated to the intervention, such as individual differences or external stressors experienced by participants. The six-week IMT program significantly enhanced respiratory muscle performance and inspiratory power in healthy young adults, confirming IMT as an effective non-invasive strategy for improving inspiratory function. Although psychological outcomes did not reach statistical significance, positive directional trends suggest potential benefits that warrant further exploration. Improvements in VO2 peak power also suggest that IMT may improve exercise capacity in recreationally active young adults. Future studies with larger samples are essential to fully evaluate the psychological impact of IMT and its potential value for promoting psychophysiological well-being in healthy populations. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.