Background: Rehabilitation is an effective method for improving the overall health of patients who have experienced the long-term effects of COVID-19. Methods: The double-blind, randomized prospective study assessed the effectiveness of a 6-week rehabilitation program among post-COVID-19 patients. A total of 59 patients under treatment following COVID-19 were randomly divided into two groups. Both groups completed the same six-week comprehensive exercise training program supported by a respiratory muscle trainer (Threshold IMT) during out-patient sessions. The control group performed placebo IMT. Respiratory muscle strength, chest wall expansion, spirometry, and diaphragm ultrasonography measurements were taken before and after the six weeks. Results: The applied rehabilitation program improved respiratory muscle strength in both the study and control groups (p < 0.001). There was a significant chest circumference increase in the study group (p < 0.001). Spirometric parameters improved in both groups, with the study group showing a greater improvement: 8.02% in FEV1 (p < 0.001), 13.24% in FVC EX (p < 0.001) and 9.67% in PEF (p < 0.001). Rehabilitation also increased diaphragm thickness during maximum inhalation in both groups. Conclusions: Based on the study findings, the specialized outpatient rehabilitation program developed for post-COVID-19 patients has proven to be effective and safe.

The COVID-19 pandemic has brought significant attention to the respiratory system, with much focus on lung-related disorders. However, the diaphragm, a crucial component of respiratory physiology, has not been adequately studied, especially in the context of long COVID. This review explores the multipotential role of the diaphragm in both respiratory health and disease, emphasizing its involvement in long-term complications following SARS-CoV-2 infection. The diaphragm’s fundamental role in respiratory physiology and its impact on balance and posture control, breathing patterns, and autonomic nervous system regulation are discussed. This review examines complications arising from COVID-19, highlighting the diaphragm’s involvement in neurological, musculoskeletal, and inflammatory responses. Particular attention is given to the neuroinvasive impact of SARS-CoV-2, the inflammatory response, and the direct viral effects on the diaphragm. The diaphragm’s role in long COVID is explored, with a focus on specific symptoms such as voice disorders, pelvic floor dysfunction, and sleep disturbances. Diagnostic challenges, current methods for assessing diaphragmatic dysfunction, and the complexities of differentiating it from other conditions are also explored. This article is the first to comprehensively address diaphragmatic dysfunction resulting from COVID-19 and long COVID across various physiological and pathological aspects, offering a new perspective on its diagnosis and treatment within a multisystem context.

This study provides a comprehensive evaluation of the long-term clinical outcomes of an original rehabilitation programme for patients with long-COVID, highlighting the sustained therapeutic benefits over a six-month period. Seventy‑five patients with long‑COVID symptoms completed a six‑week programme comprising three weekly outpatient sessions. Participants were randomly assigned to two groups following an identical comprehensive protocol, incorporating aerobic training, respiratory exercises, strength and general fitness training, stretching, and respiratory resistance training with a respiratory muscle trainer, with the control group receiving placebo IMT. The study evaluated the programme’s effectiveness by assessing respiratory function (spirometry, muscle strength, chest expansion, and DTF), voice and speech quality, and symptom persistence. The six-month follow-up analysis demonstrated statistically significant retention of improvements in functional and qualitative parameters compared with post-rehabilitation values, with further gains relative to baseline. Our findings indicate that the multi‑component rehabilitation programme is broadly beneficial, with the greatest functional gains in patients with lower baseline capacity, while offering equitable, low‑cost support across age and sex groups and enabling targeted allocation of intensive monitoring to those with the highest potential for clinically meaningful improvement. The study is the first comprehensive analysis of the relationship between long‑COVID and voice and speech‑related disabilities, while also validating the clinical efficacy of the intervention. Clinical trials registration : NCT05449379; 08/07/2022.