The aim of this study was to evaluate the effect of incorporated 4-week inspiratory muscle training (IMT) in standard stage II cardiac rehabilitation in patients with heart failure (HF) on the subjects' physical capacity.
Material and methods: Thirty post-myocardial infarction patients with HF and reduced left ventricular ejection fraction below 50 % who met the inclusion criteria were enrolled. Allocation to groups was done randomly (according to the distribution table): 14 patients (age 71.6±7.9) who performed IMT (IMT group) and 16 patients (age 70.7±6.9) who received CR training (Sham group) in addition to individually tailored training as part of stage II cardiac rehabilitation. The groups were homogeneous in terms of anthropometry and pharmacotherapy used. The methods used in the study were respiratory muscle strength measurement and spiroergometric testing. The following parameters were assessed before and 4 weeks after the intervention: maximal inspiratory and expiratory pressures (PImax, PEmax,), spiroergometric parameters: peak VO2, VE, HR, MET. The intensity of IMT was determined individually based on PImax. In the IMT group, training with an increasing load from 30 to 60% of PImax was applied, taking place 7 times a week (21 minutes per day; 7 cycles of 2 minutes, 1 minute rest between each cycle). Sham group - performed sham inspiratory muscle training (load 1 cm H2O) - placebo procedure. The following were used for statistical analysis: analysis of variance ANOVA, post hoc NIR test, Chi² test. The level of statistical significance was taken at α=5%.
In the IMT group, a significant increase in inspiratory muscle strength (p=0.000) was observed after cardiac rehabilitation with IMT. A significant increase in peak oxygen consumption, VE and MET energy expenditure and a significant reduction in peak HR (p=0.000) were also observed in patients. Comparative analysis between groups showed significantly greater increases in inspiratory muscle strength, peak VO2, VE and MET values in patients in the IMT group and a significantly greater reduction in peak heart rate compared to the Shamp group.
The additional use of IMT in stage II of cardiac rehabilitation in post-MI patients with HF and a left ventricular ejection fraction below 50% significantly increased respiratory muscle strength and peak oxygen consumption values compared with those undergoing standard rehabilitation alone.
Incorporating IMT training into CR enhances the effect of improving peak oxygen consumption and thus improves the prognosis of patients with heart failure.
cardiac rehabilitation
respiratory muscle training
