Dual-resistance respiratory muscle training with a novel individualized respiratory exercise device: a randomized controlled trial

Respiratory muscle training (RMT) is known to enhance exercise performance and respiratory efficiency; however, the optimal approach and device design for healthy adults remain underexplored. This study aimed to investigate the effects of a novel individualized respiratory exercise device that integrates inspiratory and expiratory muscle training with real-time visual feedback on pulmonary function, respiratory muscle strength, and functional capacity in healthy adults. In this prospective, single-blinded, randomized controlled trial, 40 healthy adults aged 18–65 were randomly assigned to an experimental group (EG; novel individualized respiratory exercise device) or a control group (CG; Threshold® IMT + PEP devices). Both groups trained 5 days per week for 8 weeks at 40% of their baseline maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Outcome measures included spirometry, MIP, MEP, and 6-minute walk test (6MWT) parameters, including inspiratory capacity change (ΔIC), minute ventilation (VEpeak), and dynamic hyperinflation. Both groups showed significant increases in MIP and MEP (p<0.001), with no intergroup differences. No significant changes were observed in FVC%, FEV1%, or FEF25-75% (p>0.05). However, 6MWT distance improved significantly in both groups (p<0.001), with greater gains in the EG (p=0.024, ηp²=1.03). VEpeak increased significantly only in the EG (p=0.013), accompanied by a significant group-by-time interaction for ΔIC (p<0.001, ηp²=3.40), indicating reduced dynamic hyperinflation. Both the novel and conventional RMT devices effectively improved respiratory muscle strength and functional capacity in healthy adults. However, the novel individualized respiratory exercise device provided superior improvements in ventilatory efficiency and inspiratory capacity. These findings suggest that combined inspiratory–expiratory training with individualized load adjustment and visual feedback may offer a more efficient and engaging method for optimizing ventilatory mechanics and overall exercise performance in health and rehabilitation settings.