The effects of inspiratory muscle training on respiratory function and aerobic capacity in sedentary adolescents: A single-blind randomized controlled trial

Inspiratory muscle training (IMT) is widely implemented among athletes and patients, but its effects in sedentary adolescent students remain unclear. This randomized controlled trial investigated the effects of 12-week IMT on respiratory function and aerobic capacity in sedentary adolescent boys. For this aim, 41 sedentary male-adolescents (16-18 years) were assigned randomly into IMT (n = 20) or Sham (n = 21) group. IMT was performed 3 days/week, 3 sets of 30 repetitions daily over 12 weeks. The forced vital capacity (FVC), maximal inspiratory pressure (MIP), peak inspiratory flow (PIF), forced inspiratory volume (FIV), maximum expiratory pressure (MEP), estimated maximal oxygen uptake (VO_2max), running distance, maximal heart rate and heart rate recovery at 1/3/5 minute (HRR1/3/5) were assessed before and after intervention. Two-way mixed ANOVA or generalized estimating equations was conducted to analyze group×time interactions. Significant group×time interactions were observed for all respiratory function parameters and for VO₂max, running distance, and HRR1 (P < 0.05). Post-intervention, the IMT group showed significantly higher MIP, PIF, FIV, VO₂max, running distance, and HRR1 compared to the Sham group (P < 0.05). The augmentation value was also substantially greater in the IMT group across all outcomes (P < 0.05). These findings suggest 12-week IMT effectively enhances respiratory function and aerobic endurance in sedentary adolescent males. This trial was registered at the Chinese Clinical Trial Registry (Registration ID ChiCTR2600117069, 3/12/2025).