RESUMEN
Purpose: The main aim of the trial was to assess the effectiveness of inspiratory muscle training on respiratory muscle strength, functional capacity, fatigue, and stress in post-surgical breast cancer survivors. Methods: Forty-seven females who had undergone unilateral post-mastectomy were randomly assigned to an intervention group (IG; n = 24) and a control group (CG; n = 23). Both groups received aerobic exercise training. In addition, the intervention group received inspiratory muscle training 3 days a week for 8 weeks. Maximum inspiratory and expiratory pressure (Pimax) (Pemex), 6-minute walk test, Handgrip strength by hand-held dynamometer, Fatigue Assessment Scale (FAS), and Perceived Stress Scale pss 10 values were measured before the training and then at the eighth week for both groups. Results: No differences were detected between the groups in terms of sample and clinical characteristics 8 weeks post-intervention. In favor of the intervention group, a significant difference with medium to high effect size was found in terms of Pimax, Pemax, FAS, PS, and 6MWT (p < 0.05). However, there was no difference in terms of handgrip strength (p-value: 0.072), with a medium effect size (0.070). Regarding within-group comparisons, IG exhibited substantial differences in all outcome measures (p < 0.05) compared to CG, with the exception of PImax and 6MWT. Conclusion: In post-operative breast cancer survivors, respiratory muscle training combined with aerobic training increases respiratory muscle strength and functional ability while lowering stress and tiredness.