Inspiratory Muscle Pressure and Diaphragmatic Strength in Women With Long COVID-19: A Pressure Biofeedback-Guided Training Study

Coronavirus disease (COVID-19), caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has resulted in a growing population of individuals experiencing persistent symptoms after the acute phase of infection. Post-COVID-19 conditions frequently involve respiratory impairment, characterized by reduced lung capacity, decreased maximal inspiratory pressure, and weakness of the respiratory muscles, particularly the diaphragm. These impairments are attributed to systemic inflammation, cytokine storm, prolonged immobilization, increased respiratory workload, and neuromuscular involvement during and after COVID-19 infection. The diaphragm is the primary inspiratory muscle and plays a critical role in maintaining adequate ventilation. Diaphragmatic dysfunction following COVID-19 may manifest as reduced diaphragmatic excursion, decreased muscle thickness, and diminished inspiratory pressure generation. Maximal inspiratory pressure (MIP) is a widely used, non-invasive parameter for assessing inspiratory muscle strength and reflects the functional capacity of the diaphragm and accessory inspiratory muscles. Reduced MIP values indicate inspiratory muscle weakness and are associated with impaired respiratory function and reduced physical capacity. Women after COVID-19, particularly in the postpartum period, represent a vulnerable population for respiratory muscle weakness. Physiological changes related to pregnancy and childbirth, combined with the effects of COVID-19 infection, may exacerbate diaphragmatic weakness and impair respiratory mechanics. Despite the clinical relevance of this condition, data regarding targeted respiratory rehabilitation interventions in this population remain limited. Respiratory rehabilitation has been shown to improve respiratory muscle strength, reduce dyspnea, and enhance quality of life in post-COVID-19 patients. One rehabilitation approach is indirect diaphragmatic muscle training using pressure biofeedback. This technique utilizes a pressure-sensing device placed at the lumbosacral region to provide real-time feedback during diaphragmatic breathing exercises. The feedback allows patients to optimize diaphragmatic activation while minimizing excessive chest wall movement, thereby promoting effective and controlled diaphragmatic contraction. Indirect diaphragmatic training with pressure biofeedback is designed to strengthen the diaphragm by encouraging abdominal expansion during inspiration. Repeated training sessions aim to increase diaphragmatic endurance and strength, leading to improvements in maximal inspiratory pressure and overall respiratory function. This method has been used in respiratory rehabilitation settings in Indonesia; however, its specific effectiveness in improving diaphragmatic strength and inspiratory pressure in women after COVID-19 has not been adequately studied. This study employs a randomized, single-blind clinical trial design to evaluate the relationship between changes in maximal inspiratory pressure and changes in diaphragmatic strength following indirect diaphragmatic muscle training using pressure biofeedback. Participants are allocated to either a control group or an intervention group. The intervention group receives structured indirect diaphragmatic training with pressure biofeedback over a defined training period, while both groups undergo standardized assessments of inspiratory pressure and diaphragmatic muscle function at predetermined time points. Diaphragmatic strength is assessed using ultrasonographic evaluation of diaphragmatic movement and thickness, while maximal inspiratory pressure is measured using a pressure manometer. These measurements allow for objective evaluation of respiratory muscle function and enable analysis of the correlation between inspiratory pressure improvement and diaphragmatic muscle strengthening following the intervention. The primary scientific focus of this study is to determine whether improvements in maximal inspiratory pressure are correlated with improvements in diaphragmatic strength following indirect diaphragmatic muscle training guided by pressure biofeedback. By examining this relationship, the study aims to provide evidence supporting the role of pressure biofeedback-guided diaphragmatic training as a respiratory rehabilitation modality for women recovering from COVID-19. The findings of this study are expected to contribute to the development of evidence-based respiratory rehabilitation strategies for post-COVID-19 conditions, particularly in women, and to support the integration of pressure biofeedback techniques into comprehensive post-COVID-19 rehabilitation programs.