Inspiratory muscle weakness further impairs exercise capacity and respiratory functions and increases dyspnea perception in patients with heart failure.

Thirty to fifty percent of patients with heart failure (HF) exhibit inspiratory muscle weakness (IMW). However, it is not adequately known whether IMW further impairs exercise capacity, pulmonary function (PF), lower and upper extremity muscle strength, perception of dyspnea and fatigue, physical activity (PA) level, and quality of life (QoL) in HF patients. The study aimed to compare the abovementioned outcomes in HF patients with IMW, preserved inspiratory muscle strength (PIMS), and healthy controls (HC). In this retrospective, cross-sectional study, 41 HF patients with IMW, 30 with PIMS, and 41 HC were assessed. IMW was defined by MIP < 62-83 cmH2O for females and males. Functional exercise capacity ((6-min walk test (6-MWT)), PF, peripheral muscle strength, MIP, MEP, dyspnea, fatigue, PA level, and QoL were compared. HF patients with IMW showed significantly reduced exercise capacity, PF, muscle strength, and increased dyspnea level compared to those with PIMS (p < 0.05). Both HF groups (IMW and PIMS) demonstrated increased fatigue levels, decreased PA levels, and QoL compared to HC (p > 0.05). IMW in HF patients worsens exercise capacity, PF, and muscle strength while increasing dyspnea. The decline in fatigue, PA levels, and QoL is similar in HF patients with IMW and PIMS. Inspiratory muscle strength should be evaluated during the initial stages of the disease, and inspiratory muscle training should be initiated as early as possible.