Pelvic floor muscles (PFMs) in women play a key role, and their proper functioning depends on the coordinated interaction with other anatomical structures, particularly the diaphragm and deep abdominal muscles, which together constitute the so-called core stabilizing unit. The aim of this study was to evaluate the effects of diaphragmatic breathing therapy on pelvic floor muscle function and stress levels in healthy women. The randomized, controlled, parallel-group trial (allocation 1:1) included 42 women aged 21–30 years who met the inclusion and exclusion criteria. The experimental group received diaphragmatic breathing therapy. The following assessment tools were used: Surface Electromyography (sEMG), the Sexual Satisfaction Questionnaire in Close Relationships (KSS) by M. Plopa, and the Perception of Stress Questionnaire (KPS) by M. Plopa and R. Makarowski. In the experimental group, a significant reduction in resting PFM activity was observed in the final stage of the measurement protocol, along with a tendency toward decreased activity during relaxation phases. A trend toward increased amplitude during phasic and tonic contractions was also noted, more pronounced after therapy than in the control group, although not statistically significant. No significant associations between stress dimensions and sexual satisfaction were found in the control group, whereas in the experimental group, higher worry, reduced sense of meaning, low agency and pessimism correlated with lower sexual satisfaction and difficulties achieving orgasm. These findings suggest that diaphragmatic breathing therapy may reduce resting pelvic floor muscle activity and perceived emotional stress.

This exploratory randomized study examined whether manual diaphragm therapy is associated with masseter muscle activity, mandibular motor function, and perceived stress in healthy women. Forty-two asymptomatic women aged 20–30 years were randomized to an intervention group (n = 20), receiving six sessions over two weeks, or a no-intervention control group (n = 22). Before and after the intervention period, bilateral masseter surface electromyography (sEMG) was recorded at rest and during standardized mandibular motor tasks; mandibular range of motion was measured with an electronic caliper, and perceived stress was assessed using the Perceived Stress Questionnaire. Non-parametric tests with Bonferroni correction were applied. No significant within-group changes were observed in resting masseter sEMG. The only task-related within-group result that remained significant after correction was a reduction in normalized right masseter mean RMS amplitude during protrusion in the intervention group (p = 0.001; adjusted p = 0.032; r = 0.685). Mandibular range of motion increased in both groups, but change scores did not differ between groups. Stress-related outcomes and correlations with sEMG or mandibular motion were not significant after adjustment. These findings do not demonstrate consistent group-specific effects. The isolated within-group finding should be regarded as preliminary and hypothesis-generating and cannot be attributed specifically to manual diaphragm therapy.