Effects of low workload respiratory training with steam inhalation on lung function in stable asthma: A controlled clinical study

To investigate effects of low workload respiratory muscle training (RMT) on respiratory muscle power and lung function in asthmatics, we recruited asthmatic persons who performed a 4-week training programme. The training included 20 daily ex- and inhalations with counter pressure 30% from the individual maximal expiratory pressure (MEP). Lung function was measured before and after the training programme and a follow-up period. The study also included several subjective endpoints for respiratory symptoms. A significant increase in a training group (n = 27) compared with a control group (n = 20) was seen in MEP (+12.4%, vs. +3.5%, p = 0.086), maximal inspiratory pressure (MIP) (+21.1% vs. +0.82%, p = 0.023), slow vital capacity (VC) (+3.7% vs. +1.5%, p = 0.023) and in forced expiratory time (FET, +15.5%, vs. −5.0%, p = 0.022). After being a control for group A, also group B performed similar RMT as group A. In the combined group (A and B, n = 47) MEP (11.3%, p = 0.003), MIP (19.73%, p < 0.001), VC (4.1%, p < 0.001) and FET (14.7%, p < 0.001) increased significantly from the baseline. Changes in other lung function variables were not indicative. On a scale of 1–5, the subjects perceived improvement in reduction of mucus secretion in the airways (median 3, p < 0.001), alleviation of coughing (median 3, p < 0.001) and reduction in dyspnoea (median 3, p < 0.001). As a conclusion, low workload respiratory training of 4 weeks improved respiratory muscle power and increased VC in patients with stable asthma.