Effects of Diaphragmatic Therapy on Pelvic Floor Muscle Activity, Stress Levels, and Sexual Life Satisfaction in Polish Women

Abstract

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.

1. Introduction

Pelvic floor muscles (PFMs) in women are integral to maintaining urinary and fecal continence, supporting pelvic organs, contributing to lumbopelvic stability, and enhancing sexual function [1]. The proper function of these muscles relies on their synergistic relationship with other anatomical structures, particularly the diaphragm and deep abdominal muscles, collectively referred to as the “core stabilizing unit” [2]. Effective coordination between the diaphragm and PFM is critical for regulating intra-abdominal pressure (IAP) and maintaining postural stability [3].

During inhalation, the diaphragm contracts and moves downward, increasing IAP and inducing reflexive relaxation of the PFM. During exhalation, the diaphragm ascends while the PFMs contract, thus supporting expiration and trunk stabilization [3]. Disruptions in this coordination—often associated with respiratory dysfunction—may lead to compensatory tension within the pelvic floor, potentially resulting in pelvic pain, urinary incontinence, and sexual dysfunction [2].

Impaired diaphragmatic function is not confined to individuals with diagnosed medical conditions but can also be observed in seemingly healthy individuals. This is largely attributed to the widespread prevalence of upper chest (thoracic) breathing patterns that fail to properly engage the diaphragm. Such dysfunctional breathing is increasingly common among individuals experiencing chronic stress, fast-paced lifestyles, and prolonged sedentary behavior [4].

In recent years, growing attention has been paid to the role of breathing techniques and diaphragmatic work in reducing stress and improving the functioning of the musculoskeletal and reproductive systems in women. Research suggests that interventions combining physiotherapy with psychological support can contribute to the normalization of cortisol levels and enhance overall well-being in women with endometriosis [5]. These findings may serve as a basis for further investigation into the efficacy of breathing techniques, such as diaphragmatic therapy, in relation to pelvic floor muscle function, stress levels, and sexual quality of life.

There is evidence suggesting that even a single session of diaphragmatic therapy may have beneficial effects on psychological stress responses or reduce depressive symptoms [6,7]. Furthermore, it has been observed that a single relaxation session induced by diaphragmatic breathing can enhance the antioxidant defense capacity in athletes following exhaustive exercise. These effects are associated with a decrease in cortisol levels [8].

A positive correlation between perceived stress levels and pain intensity suggests that interventions aimed at reducing stress may substantially alleviate pain symptoms [9,10]. These effects may be linked to dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and the action of glucocorticoids [11]. Studies have shown that women experiencing high levels of stress exhibit reduced genital response to sexual stimuli and elevated cortisol levels, both of which may negatively impact sexual functioning [12].

Despite increasing clinical interest, comprehensive studies investigating the interactions between diaphragmatic breathing, pelvic floor muscle activity, psychological stress, and sexual satisfaction in women remain scarce. This knowledge gap underscores the need for an integrative therapeutic approach that incorporates both musculoskeletal and psychosocial dimensions. By exploring these multidimensional relationships, we may enhance our understanding of how non-invasive myofascial techniques can contribute to holistic care strategies in women’s health.

In light of these physiological and psychological interconnections, the present study aimed to determine whether targeted diaphragm therapy could affect pelvic floor muscle activity, perceived stress levels, and sexual satisfaction in women.

The research question that guided this study was: Does diaphragm therapy improve PFM activity, reduce stress levels, and enhance sexual satisfaction in women?

2. Materials and Methods

2.1. Participants

A total of 76 women were initially recruited for the project. Based on the inclusion and exclusion criteria, 42 Polish women aged 21–30 years (mean age: 24.79 ± 2.75) were ultimately included in the study. Participants’ body mass ranged from 48 to 89 kg (mean: 61.04 ± 9.31), and their height ranged from 155 to 178 cm (mean: 167.17 ± 5.1). The body mass index (BMI) of the participants ranged from 17.16 to 32.69 (mean: 22.18 ± 3.03). A detailed characterization of the study group is provided in Table 1.

Table 1. Characteristics of the participants.

Parameter		Total (n = 42)
Age [years]	Mean (SD)	24.79 (2.75)
	Median (quartiles)	24 (23–26)
	Range	21–30
	n	42
Education level	Vocational	1 (2.38%)
	Secondary	16 (38.10%)
	University	25 (59.52%)
Type of relationship	Marriage	6 (14.29%)
	Informal	36 (85.71%)
Relationship duration [months]	Mean (SD)	40.29 (28.48)
	Median (quartiles)	36 (13.5–64.5)
	Range	2–96
	n	42

SD—standard deviation.

The inclusion criteria were as follows: provision of written informed consent, age between 20 and 30 years, no history of pregnancy, childbirth, or miscarriage (confirmed nulliparity), sexual activity, and absence of self-reported urogenital dysfunction, neurological disorders, visual impairments, or musculoskeletal conditions. Additionally, participants were required to have had no physiotherapy targeting the diaphragm or pelvic floor muscles within the previous six months.

The exclusion criteria were as follows: pregnancy, hypertension, diagnosed urogenital dysfunctions, pathological changes within the pelvic region, history of surgical procedures or injuries involving the abdominal cavity or spine within six months prior to the study, neurological or musculoskeletal disorders, systemic diseases, use of hormonal contraception, and participation in physiotherapy within six months prior to the commencement of the study.

Participant recruitment was conducted through advertisements targeting the young adult population in Kraków and the surrounding areas (Poland), posted on social media platforms (Instagram, Facebook). Recruitment took place between 11 June and 15 July 2024, and all measurements were completed by 30 October 2024.

The study was conducted in the Functional Diagnostics Laboratory, which is part of the Central Scientific Research Laboratory at the Bronisław Czech University of Physical Education in Kraków. Ethical approval for the study was obtained from the Bioethics Committee (KBKA/43/O/2024). The project was funded by the Ministry of Science under the program Regional Initiative of Excellence for the years 2024–2027 (project number RID/SP/0027/2024/01; total funding: PLN 4,053,904.00).

Participants were randomly assigned to two groups in a 1:1 ratio using simple randomization. Group allocation was determined by drawing a sealed, opaque envelope containing the group designation (I or II), which had been prepared by a researcher who was not involved in either the assessment or the intervention. Group I (n = 20) received diaphragmatic therapy, which included selected techniques targeting the diaphragm (diaphragm normalization, work on the central tendon, and work on the crura of the diaphragm). Group II (n = 22) served as a control group with no intervention.

A total of six therapeutic sessions were applied to the diaphragm over a two-week period. Therapy was administered three times per week (Monday, Wednesday, and Friday). To evaluate both groups, assessments were performed before and after the six therapy sessions in Group I, and at equivalent time points in Group II without intervention.

The study was a randomized controlled trial with parallel groups. The investigator responsible for the measurements was blinded to the participants’ group allocation. The participants were not informed of the exact research hypothesis but were told that both groups would be evaluated in terms of physiological responses associated with diaphragm function.

Prior to participation, all individuals were informed about the study aims, procedures, and the therapy protocol, as well as their right to withdraw from the study at any time without consequences. Written informed consent was obtained from all participants prior to inclusion.

2.2. Research Tools

To assess the effectiveness of the applied therapy, standardized research instruments were employed, including surface electromyography (sEMG) to measure the bioelectrical activity of the pelvic floor muscles, the Perceived Stress Questionnaire (PSQ) developed by Mieczysław Plopa and Mieczysław Markowski to evaluate the level of psychological stress, and the Sexual Satisfaction Questionnaire in Close Relationships (SSQ) by Mieczysław Plopa to analyze the level of satisfaction with sexual life.

2.2.1. Surface Electromyography (sEMG)

Surface electromyography (sEMG) was employed to assess the bioelectrical activity of the PFM, using the Noraxon Ultium device (Noraxon U.S.A. Inc., Scottsdale, AZ, USA) and theLifecare PR-02 vaginal probe (Everyway Medical Instruments Co., Ltd., New Taipei City, Taiwan). Findings from other studies suggest that differences in probe placement during PFM activation did not have a significant impact on the recorded sEMG signals [13]. The signal was recorded with 16-bit resolution at a sampling frequency of 1500 Hz. sEMG signal processing was performed using the MyoResearch XP software version 1.0 (Noraxon USA, Inc., Scottsdale, AZ, USA). The vaginal probe, measuring 76 mm in length and 28 mm in diameter, featured two longitudinal stainless steel and nickel plates.

Prior to each measurement, the sEMG system was calibrated in accordance with the manufacturer’s recommendations to ensure signal accuracy and minimize baseline noise. Signal quality was visually inspected before recording to verify stable electrode impedance and the absence of artifacts.

The electromyographic data were band-pass filtered between 10 and 500 Hz, rectified, and smoothed using RMS filtering with a 100 ms window. The signals were expressed in microvolts (μV) and as a function of frequency (Hz). In addition, the sEMG data were normalized to the maximum recorded RMS EMG amplitude of the pelvic floor muscles. performed at the beginning of the protocol.

Measurements were not conducted during menstrual bleeding. Prior to the assessment, participants were asked to completely empty their bladders. After donning protective gloves and applying conductive gel, the participant independently inserted the vaginal probe, positioning the electrodes toward the iliac crests. The physiotherapist verified the correct placement of the probe. The examination was carried out in a supine position, with a cushion placed under the knees to allow for slight flexion of the hip and knee joints. The spine was maintained in a neutral position, and the upper limbs were positioned parallel to the torso.

The study followed the assessment protocol described by Oleksy et al. [14], which consisted of five stages:

• Participants were instructed to relax the pelvic floor muscle (PFM) following a 60-s rest period prior to the assessment, which was divided into three segments: I—5 s, II—5 s, and III—50 s.
• Participants were then asked to contract the PFM as quickly as possible and to immediately and fully relax it. This phase included five phasic (rapid) contractions, each lasting 2 s, with 10-s rest intervals between contractions.
• In the next phase, participants were instructed to contract the PFM as strongly as possible, maintain the contraction for 10 s, and then fully relax. This consisted of five tonic contractions, each followed by a 10-s rest.
• Subsequently, participants were asked to contract the PFM to a submaximal level that could be sustained for 60 s without changes in muscle tension. This phase involved one 60-s endurance contraction.
• Finally, participants were instructed to relax the PFM during a 60-s resting period following the exercises.

2.2.2. The Sexual Satisfaction Questionnaire in Close Relationships (SSQ) by M. Plopa

To assess the level of sexual satisfaction before and after the series of therapy sessions, the Sexual Satisfaction Questionnaire in Close Relationships (Poland) was used. This Polish psychometric instrument was developed for research on the subjective perception of sexual quality of life. The questionnaire consists of 10 items rated on a 7-point Likert scale (from 1—“definitely not” to 7—“definitely yes”). The SSQ comprises three subscales: intimacy, caresses, and sex. The sex subscale refers to physical aspects such as the level of satisfaction with sexual intercourse and the experience of orgasm, for example, “I am satisfied with the quality of our sexual intercourse”. The intimacy subscale concerns the depth of the romantic relationship, communicative openness, mutual trust, the feeling of joy from being close to one’s partner, cuddling, the attractiveness of the partner’s scent, and the readiness for erotic intimacy, as illustrated by the statement, “I can openly talk with my partner about my feelings and desires”. The caress subscale includes the assessment of satisfaction with foreplay, behaviors leading to intimacy, mutual touching, and other forms of erotic contact outside of sexual intercourse, for instance, “I like when my partner touches me affectionately” [15].

The questionnaire allows for the assessment of overall sexual satisfaction as well as specific dimensions of sexual quality of life. It was developed and validated within the Polish cultural context using data collected in Poland. Participants were randomly divided into two subsamples: one for Exploratory Factor Analysis (EFA) and another for Confirmatory Factor Analysis (CFA). Both analyses supported a clear three-factor structure, with excellent model fit indices (CFI = 0.96, RMSEA = 0.048, SRMR = 0.043), confirming the theoretical model’s consistency with the empirical data. The instrument demonstrated high internal consistency, with Cronbach’s alpha coefficients ranging from 0.83 to 0.88 for subscales and 0.91 for the total score, indicating strong reliability. Convergent validity was confirmed through positive correlations with the Marital Adjustment Test (MAT), the Satisfaction with Life Scale (SWLS), and M. Rosenberg’s Self-Esteem Scale (SES) [15].

Discriminant validity analyses further supported the measure, revealing equivalence across gender and consistent relationships with age and relationship status. Overall, the questionnaire exhibits robust psychometric properties and serves as a reliable and valid tool for assessing sexual satisfaction in both research and clinical contexts [15].

2.2.3. The Perceived Stress Questionnaire (PSQ) by M. Plopa and R. Makarowski

To measure the subjective level of stress, the Perceived Stress Questionnaire (Poland), developed by M. Plopa and R. Makarowski in 2010, was used. This instrument is designed to assess individual differences in the experience and perception of stress in everyday functioning. The questionnaire consists of 27 test items, divided into the following subscales: emotional tension (e.g., “I often feel irritated for no apparent reason”), intrapsychic stress (e.g., “I feel that I am unable to meet my own expectations”), external stress (e.g., “I have the impression that too much is expected of me”), and a lie scale (e.g., “I never make promises I cannot keep”). Respondents rate each statement on a five-point Likert scale, ranging from “definitely not” to “definitely yes” [16].

In addition to subscale scores, it is possible to obtain a general stress index, which serves as a synthetic measure of psychological burden and represents the sum of the three subscales. The questionnaire also includes a lie scale, which makes it possible to identify individuals who present themselves in an overly favorable light by attributing to themselves socially desirable behaviors that are in fact rare. Such a tendency may stem from a lack of self-criticism, limited insight, or deliberate misrepresentation [16].

The PSQ demonstrates good psychometric properties. The authors report internal consistency coefficients (Cronbach’s alpha) ranging from 0.70 to 0.81, indicating that it is a reliable tool for measuring stress levels in both men and women. The reliability coefficients for women in individual scales are as follows: for Emotional Tension—Cronbach’s alpha = 0.82, for External Stress—Cronbach’s alpha = 0.70, for Intrapsychic Stress—Cronbach’s alpha = 0.70, and for the Lie Scale—Cronbach’s alpha = 0.57 [16].

The validity of the questionnaire is satisfactory and has been confirmed based on correlation coefficients with other psychological instruments: the NEO-FFI, C. D. Spielberger’s Questionnaire, and the BDI—Beck Depression Inventory. The normalization of the PSQ was carried out on the basis of studies conducted among individuals representing both urban and rural populations in Poland. The sample was diverse in terms of gender, age, marital status, education, place of upbringing, occupation, and health condition. The questionnaire is widely used in psychological and clinical research, as well as in diagnostic practice [16].

2.3. Intervention

In the enrolled participants, therapy was performed using manual techniques aimed at normalizing diaphragmatic [17]. Diaphragmatic tension was assessed manually by a qualified physiotherapist. The therapeutic protocol included three manual techniques:

• Normalization of the costal arches (bilateral work on the costal margins): During this technique, participants were instructed to take a deep inhalation, while the therapist facilitated the upward and outward movement of the costal arches. During exhalation, the therapist maintained the achieved movement and prevented regression.
• Work on the central tendon of the diaphragm: The therapist placed the heel of the hand above the umbilicus and followed the participant’s inhalation and exhalation. During exhalation, the heel of the hand was gradually pressed deeper into the tissue and rotated clockwise.
• Work on the diaphragmatic crura: This technique was performed with the participant in the prone position. The therapist placed one hand on the participant’s thigh in the popliteal fossa region and the other hand over the diaphragmatic crura at the level of L1–L2, lateral to the spine, on the side where the therapist was positioned. The participant was instructed to inhale deeply and then exhale. During exhalation, the participant was asked to maximally relax the entire body. With subsequent repetitions, the distance between the therapist’s hands was gradually increased.

Each technique was performed in synchronization with the participant’s breathing cycle, with inhalation and exhalation repeated several times. The duration of each therapeutic session was not predetermined but depended on the achievement of improved diaphragmatic mobility.

2.4. Statistical Analysis

The statistical analysis was performed using STATISTICA 12.0 Pl (Statsoft Polska, Krakow, Polska). Qualitative variables were presented as counts and percentages, while quantitative variables were expressed as mean and standard deviation. In the analysis of questionnaire results, comparisons of quantitative variables between two repeated measurements were performed using the Wilcoxon test. In the analyses based on questionnaire data, no correction for multiple testing was applied, as these analyses were exploratory. To assess differences in pelvic floor muscle activity assessed by electromyography, a two-way ANOVA was conducted, with one main factor between groups (experimental vs. control) and the other main factor being the repeated measure (time: pre- and post-intervention or pre- and post-break). For the analysis of PFM activity, post hoc comparisons were conducted using Tukey’s test to control for multiple comparisons. The Shapiro–Wilk test was used to assess the normality of variable distribution. The homogeneity of variances across groups was evaluated using Levene’s test. Effect sizes were determined with Cohen’s d and classified as negligible (<0.1), small (0.1–0.3), medium (0.3–0.5), or large (>0.5) [18]. Spearman’s correlation coefficient was used to assess correlation between two quantitative variables. Differences were considered statistically significant if the test probability level was lower than the assumed significance level (p < 0.05). Based on data from another study including the bioelectrical activity of the pelvic floor muscles, a power analysis for the two-way ANOVA determined that a minimum of 16 participants per group was required to achieve a statistical power of 0.80 at a two-tailed significance level of 0.05, assuming an effect size of d = 0.8. This analysis was based on data derived from previous literature on the primary outcome variables such as PFM bioelectrical activity [19].

3. Results

3.1. Bioelectrical Activity of the PFM

3.1.1. Resting Activity of the PFM During a 1-min Rest Period (First Phase of the Measurement Protocol—Pre-Exercise)

In the second measurement, a decrease in pre-exercise resting activity of the pelvic floor muscles was observed in both groups; however, these changes were not statistically significant (p > 0.05). The calculated effect size in the experimental group indicated a medium effect. The results are presented in Table 2.

Table 2. Resting activity of the PFM during a 1-min rest period (first phase of the measurement protocol—pre-exercise).

	Measurement	Experimental Group (n = 20)		p	ES a	Control Group (n = 22)		p	ES a	p *	ES b
		Mean ± SD	%MVC			Mean ± SD	%MVC
Average mean amplitude (µV)	Before	9.57 ± 5.01	11.14 ± 5.77	0.395	−0.347	9.56 ± 6.49	11.60 ± 6.83	0.136	−0.248	0.995	−0.002
	After	8.03 ± 3.78	9.58 ± 5.04			7.94 ± 6.60	9.45 ± 8.56			1.000	−0.017

SD—standard deviation: p—between measurements; p *—between groups; ES a—effect size (Cohen’s d) within each group; ES b—effect size (Cohen’s d) between study groups; %MVC—percent of maximal voluntary contraction; µV—microvolts; %—percent.

3.1.2. Activity of the PFM During 2-s Phasic Contractions

During the assessment of 2-s phasic contractions, both groups showed an increasing trend in amplitude during contraction and a decreasing trend in resting pelvic floor muscle activity between contractions. However, observed changes were not statistically significant (p > 0.05). The data are presented in Table 3.

Table 3. Activity of the PFM during 2-s phasic contractions.

	Measurement	Experimental Group (n = 20)		p	ES a	Control Group (n = 22)		p	ES a	p *	ES b
		Mean ± SD	%MVC			Mean ± SD	%MVC
Average peak amplitude (µV)	Before	82.51 ± 33.35	88.02 ± 16.79	0.923	0.109	74.96 ± 32.89	86.03 ± 17.60	0.984	0.054	0.859	−0.228
	After	85.71 ± 24.98	94.03 ± 12.48			76.72 ± 31.80	92.19 ± 25.23			0.784	−0.314
Time before peak (s)	Before	45.07 ± 15.46	-	0.922	0.192	52.61 ± 13.34	-	0.820	−0.257	0.355	0.522
	After	47.93 ± 14.24	-			48.84 ± 15.89	-				0.060
Average resting tension between phasic contractions (µV)	Before	12.74 ± 6.73	14.45 ± 6.78	0.623	−0.257	12.59 ± 7.11	15.93 ± 10.77	0.437	−0.279	1.000	−0.022
	After	11.17 ± 5.40	12.57 ± 5.16			10.72 ± 6.26	13.54 ± 8.20			0.996	−0.077

SD—standard deviation; p—between measurements; p *—between groups; ES a—effect size (Cohen’s d) within each group; ES b—effect size (Cohen’s d) between study groups; %MVC—percent of maximal voluntary contraction; µV—microvolts; %—percent; s—second.

3.1.3. Activity of the PFM During 10-s Tonic Contractions

Consistent with the findings for phasic contractions, the analysis of 10-s tonic contractions in the second assessment demonstrated an increase in contraction amplitude. Following the applied therapy, the value of amplitude normalized to the maximum voluntary contraction (MVC) increased by 11.55% in the experimental group, while in the control group, the increase was 7.41%. However, these changes were not statistically significant in either group (Table 4).

Table 4. Activity of the PFM during 10-s tonic contractions.

	Measurement	Experimental Group (n = 20)		p	ES a	Control Group (n = 22)		p	ES a	p *	ES b
		Mean ± SD	%MVC			Mean ± SD	%MVC
Average mean amplitude (µV)	Before	47.52 ± 21.02	50.55 ± 12.37	0.734	0.211	47.44 ± 25.59	53.06 ± 11.31	1.000	0.010	1.000	−0.003
	After	51.47 ± 16.15	56.39 ± 10.48			47.67 ± 20.54	56.99 ± 18.43			0.938	−0.206
Time before peak (s)	Before	41.79 ± 18.92	-	0.883	−0.187	43.12 ± 21.66	-	0.958	−0.113	0.996	0.065
	After	38.47 ± 16.58	-			40.96 ± 16.17	-			0.972	0.152
Average resting tension between tonic contractions (µV)	Before	10.13 ± 4.74	11.93 ± 5.84	0.796	0.189	10.67 ± 6.51	13.08 ± 7.63	0.987	−0.105	0.996	0.095
	After	11.96 ± 12.83	12.40 ± 7.74			10.03 ± 5.65	12.90 ± 8.37			0.863	−0.195

SD—standard deviation; p—between measurements; p *—between groups; ES a—effect size (Cohen’s d) within each group; ES b—effect size (Cohen’s d) between study groups; %MVC—percent of maximal voluntary contraction; µV—microvolts; %—percent; s—second.

3.1.4. Activity of the PFM During 60-s Endurance Contractions

In the experimental group, during endurance contractions following the applied therapy, an upward trend in amplitude was observed, whereas the control group showed a slight decrease in amplitude in the second assessment. These changes were not statistically significant. Analysis of the fatigue index showed that the experimental group achieved a higher score following the applied therapy, indicating a medium effect size, whereas a decrease in this index was observed in the control group. The data are presented in Table 5.

Table 5. Activity of the PFM during 60-s endurance contraction.

	Measurement	Experimental Group (n = 20)		p	ES a	Control Group (n = 22)		p	ES a	p *	ES b
		Mean ± SD	%MVC			Mean ± SD	%MVC
Average Mean Amplitude (µV)	Before	22.63 ± 8.54	25.50 ± 8.03	0.869	0.160	25.67 ± 17.28	28.98 ± 10.57	0.929	−0.098	0.896	0.223
	After	24.62 ± 15.38	26.05 ± 7.83			24.17 ± 13.01	28.68 ± 7.86			1.000	−0.032
Median Frequency (Hz)	Before	53.45 ± 6.84	-	0.679	−0.195	56.69 ± 10.73	-	0.992	−0.043	0.696	0.360
	After	51.68 ± 10.85	-			56.26 ± 9.38	-			0.421	0.452
Mean Frequency (Hz)	Before	65.74 ± 7.05	-	0.777	−0.190	70.61 ± 11.78	-	0.997	−0.034	0.448	0.502
	After	63.91 ± 11.62	-			70.23 ± 10.86	-			0.225	0.562
F ratio	Before	1.02 ± 0.13	-	0.709	0.320	1.04 ± 0.12	-	0.211	−0.660	0.967	0.160
	After	1.06 ± 0.12	-			0.97 ± −0.09	-			0.065	−0.849

SD—standard deviation; p—between measurements; p *—between groups; ES a—effect size (Cohen’s d) within each group; ES b—effect size (Cohen’s d) between study groups; %MVC—percent of maximal voluntary contraction; µV—microvolts; %—percent; Hz—hertz, f ratio—ratio of the median frequency of the third interval to the second interval.

3.1.5. Resting Activity of the PFM During a 1-min Rest Period (Last Phase of the Measurement Protocol—Post-Exercise)

In the experimental group, during the 1-min rest period in the last stage of the measurement protocol, a significant reduction in resting PFM activity was observed after therapy (p < 0.05). No significant changes were noted in the control group in the second assessment. The results are presented in Table 6.

Table 6. Resting activity of the PFM during a 1-min rest period (last phase of the measurement protocol—post-exercise).

	Measurement	Experimental Group (n = 20)		p	ES a	Control Group (n = 22)		p	ES a	p *	ES b
		Mean ± SD	%MVC			Mean ± SD	%MVC
Average mean amplitude (µV)	Before	7.93 ± 4.00	9.40 ± 5.54	0.025	−0.431	8.79 ± 6.57	10.40 ± 6.33	0.419	−0.179	0.950	0.158
	After	6.15 ± 4.25	5.45 ± 3.86			7.71 ± 5.41	9.69 ± 7.23			0.767	0.321

SD—standard deviation; p—between measurements; p *—between groups; ES a—effect size (Cohen’s d) within each group; ES b—effect size (Cohen’s d) between study groups; %MVC—percent of maximal voluntary contraction; µV—microvolts; %—percent; the red color—statistically significant.

3.2. The Sexual Satisfaction Questionnaire in Close Relationships (SSQ) by M. Plopa and the Perceived Stress Questionnaire (PSQ) by M. Plopa and R. Makarowski

In the intervention group, statistically significant changes were observed in two stress-related variables: emotional tension and overall stress level, as measured by the Perceived Stress Questionnaire (PSQ). The emotional tension score was significantly lower after the intervention compared to baseline (p = 0.006), showing a 23% reduction. The overall stress level also decreased significantly by 17% (p = 0.012). The scores on the PSQ lie scale did not reach statistical significance in either group (Table 7).

Table 7. Comparison of the Perceived Stress Questionnaire (PSQ) and the Sexual Satisfaction Questionnaire in Close Relationships (SSQ) scores before and after the intervention in the therapy group.

Parameter	Measurement	N	Mean	SD	Median	Min	Max	Q1	Q3	p
SSQ: intimacy [sten]	Before intervention	20	5.20	1.82	5.5	1	8	4.75	6.25	p = 1
	After intervention	20	5.15	1.66	5.0	1	8	4.00	7.00
SSQ: caresses [sten]	Before intervention	20	4.40	1.85	5.0	1	8	3.00	5.00	p = 0.918
	After intervention	20	4.45	1.73	4.5	1	8	3.00	5.00
SSQ: sex [sten]	Before intervention	20	5.15	2.06	6.0	1	8	3.75	6.25	p = 0.051
	After intervention	20	6.00	1.97	6.5	1	8	5.00	7.25
SSQ: total [sten]	Before intervention	20	5.60	1.93	6.0	1	9	4.00	7.00	p = 0.253
	After intervention	20	5.95	1.85	6.0	1	10	5.00	7.00
PSQ: emotional tension [sten]	Before intervention	20	5.15	1.95	5.5	1	8	3.75	6.25	p = 0.006 *
	After intervention	20	3.95	1.88	3.5	1	8	3.00	5.00
PSQ: external stress [sten]	Before intervention	20	2.85	1.46	2.5	1	6	2.00	4.00	p = 0.112
	After intervention	20	2.45	1.28	2.0	1	5	1.00	3.25
PSQ: intrapsychic stress [sten]	Before intervention	20	3.35	1.69	3.0	1	8	2.00	4.00	p = 0.821
	After intervention	20	3.30	1.92	3.0	1	9	2.00	4.00
PSQ: lie scale [sten]	Before intervention	20	5.80	2.95	5.0	1	10	3.75	9.00	p = 0.566
	After intervention	20	5.50	2.61	5.0	1	10	3.75	7.00
PSQ: total [sten]	Before intervention	20	3.75	1.59	4.0	1	7	3.00	5.00	p = 0.012 *
	After intervention	20	3.10	1.59	3.0	1	7	2.00	4.00

p—Wilcoxon paired test * and the red color—statistically significant (p < 0.05).

In the control group, no statistically significant changes (p > 0.05) were observed in any of the assessed dimensions, either in the SSQ or the PSQ questionnaires. Similarly, the scores on the PSQ lie scale were not statistically significant (p > 0.05). The results are presented in Table 8.

Table 8. Comparison of the Perceived Stress Questionnaire (PSQ) and the Sexual Satisfaction Questionnaire in Close Relationships (SSQ) scores before and after the intervention in the control group.

Parameter	Measurement	N	Mean	SD	Median	Min	Max	Q1	Q3	p
SSQ: intimacy [sten]	Before intervention	22	5.68	1.32	5.5	3	8	5.00	6.00	p = 0.851
	After intervention	22	5.73	1.35	6.0	3	9	5.00	6.00
SSQ: caresses [sten]	Before intervention	22	4.73	1.80	5.0	1	8	3.25	6.00	p = 0.376
	After intervention	22	4.95	1.70	5.0	1	8	4.00	5.75
SSQ: sex [sten]	Before intervention	22	5.82	1.68	6.0	2	9	5.00	7.00	p = 0.08
	After intervention	22	6.14	1.67	6.0	2	9	5.25	7.00
SSQ: total [sten]	Before intervention	22	6.36	1.50	6.0	3	9	6.00	7.00	p = 0.212
	After intervention	22	6.59	1.40	6.0	4	10	6.00	7.00
PSQ: emotional tension [sten]	Before intervention	22	3.91	1.93	3.5	1	7	3.00	5.75	p = 0.503
	After intervention	22	3.77	1.63	3.5	1	7	3.00	5.00
PSQ: external stress [sten]	Before intervention	22	2.45	1.60	2.0	1	7	1.00	3.00	p = 0.39
	After intervention	22	2.64	1.65	2.0	1	7	1.25	3.00
PSQ: intrapsychic stress [sten]	Before intervention	22	2.95	1.76	3.0	1	6	1.25	4.00	p = 1
	After intervention	22	2.95	1.62	2.0	1	6	2.00	4.00
PSQ: lie scale [sten]	Before intervention	22	6.32	3.36	7.0	1	10	3.00	9.75	p = 0.495
	After intervention	22	6.09	3.10	7.0	1	10	3.00	9.00
PSQ: total [sten]	Before intervention	22	3.00	1.72	3.0	1	7	1.25	4.00	p = 0.803
	After intervention	22	3.05	1.73	3.0	1	7	2.00	3.75

p—Wilcoxon paired test.

Correlation analysis in the intervention group revealed significant and consistent associations. The SSQ intimacy subscale score after the intervention showed a significant positive correlation with the PSQ lie scale (r = 0.628; p = 0.003). A similar pattern was observed for the SSQ caress subscale, which was significantly associated with the PSQ lie scale (r = 0.461; p = 0.041). Furthermore, the SSQ lie scale positively correlated with the overall SSS score (r = 0.570; p = 0.009). Statistically significant correlations are presented in Table 9. Detailed results of the analysis are provided in Supplementary Table S1.

Table 9. Correlation between the Sexual Satisfaction Questionnaire in Close Relationships (SSQ) and the Perceived Stress Questionnaire (PSQ)—therapy group.

	R	p
SSS: intimacy [sten]—after intervention & SSQ: lie scale [sten]—after intervention	r = 0.628	p = 0.003 *
SSS: caresses [sten]—after intervention & SSQ: lie scale [sten]—after intervention	r = 0.461	p = 0.041 *
SSS: total [sten]—after intervention & SSQ: lie scale [sten]—after intervention	r = 0.570	p = 0.009 *
SSQ: intrapsychic stress [sten]—after intervention & SSS: sex [sten]—after intervention	r = −0.457	p = 0.043 *
SSQ:lie scale [sten]—after intervention & SSS: intimacy [sten]—after intervention	r = 0.628	p = 0.003 *
SSQ:lie scale [sten]—after intervention & SSS: caresses [sten]—after intervention	r = 0.461	p = 0.041 *
SSQ:lie scale [sten]—after intervention & SSS: total [sten]—after intervention	r = 0.570	p = 0.009 *
	R	p
SSQ: intimacy [sten]—after intervention & PSQ: lie scale [sten]—after intervention	r = 0.628	p = 0.003 *
SSQ: caresses [sten]—after intervention & PSQ: lie scale [sten]—after intervention	r = 0.461	p = 0.041 *
SSQ: total [sten]—after intervention & PSQ: lie scale [sten]—after intervention	r = 0.570	p = 0.009 *
PSQ: intrapsychic stress [sten]—after intervention & SSQ: sex [sten]—after intervention	r = −0.457	p = 0.043 *
PSQ:lie scale [sten]—after intervention & SSQ: intimacy [sten]—after intervention	r = 0.628	p = 0.003 *
PSQ:lie scale [sten]—after intervention & SSQ: caresses [sten]—after intervention	r = 0.461	p = 0.041 *
PSQ:lie scale [sten]—after intervention & SSQ: total [sten]—after intervention	r = 0.570	p = 0.009 *

Spearman’s correlation coefficient * and the red color—statistically significant (p < 0.05).

In the control group, unlike in the intervention group, no significant correlations (p > 0.05) were found between PSQ stress dimensions and SSQ intimacy or sexual satisfaction indicators. Similarly, no significant correlations (p > 0.05) were observed for the PSQ lie scale. Detailed results of the conducted analysis are provided in Supplementary Table S2.

3.3. Correlations Between Standardized Questionnaire Outcomes and Pelvic Floor Muscles

In the assessment of correlations between the results obtained from standardized questionnaires and the analysis of pelvic floor muscle function prior to the intervention, several associations were observed in the experimental group. A significant (p < 0.05) positive correlation was noted between the following variables: Average peak amplitude during phasic and tonic contractions [%MVC] and the SSQ intimacy scale score, Average resting tension between phasic contractions [µV] and the PSQ external stress scale score, Post-exercise resting activity [%MVC] and the PSQ intimacy scale score, as well as between Maximal voluntary contraction and the PSQ external stress scale score. Following the intervention, a significant (p < 0.05) negative correlation was observed in the experimental group between Pre-exercise resting activity [%MVC] and the SSQ caress scale score. In contrast, the variable Average peak amplitude during phasic contractions [µV] showed a significant (p < 0.05) positive correlation with the SSQ sex scale score. Statistically significant correlations are presented in Table 10. Detailed results of the analysis are provided in Supplementary Tables S3 and S4.

Table 10. Correlations between standardized questionnaire outcomes and pelvic floor muscles—Experimental group.

		R	p
Before intervention	Average peak amplitude during phasic contractions [%MVC]—before intervention & SSQ: intimacy [sten]—before intervention	r = 0.6	p = 0.005 *
	Average resting tension between phasic contractions [µV]—before intervention & PSQ: external stress [sten]—before intervention	r = 0.565	p = 0.009 *
	Average peak amplitude during tonic contractions [%MVC]—before intervention & SSQ: intimacy [sten]—before intervention	r = 0.545	p = 0.013 *
	Post-exercise resting activity [%MVC]—before intervention & SSQ: intimacy [sten]—before intervention	r = 0.474	p = 0.035 *
After intervention	Pre-exercise resting activity [%MVC]—after intervention & SSQ: caresses [sten]—after intervention	r = −0.555	p = 0.017 *
	Average peak amplitude during phasic contractions [µV]—after intervention & SSQ: sex [sten]—after intervention	r = 0.458	p = 0.042 *

Spearman’s correlation coefficient * and the red color—statistically significant (p < 0.05).

In the control group, during the first measurement, significant (p < 0.05) negative correlations were observed between the following variables: Average peak amplitude during phasic contractions [%MVC] and the overall SSQ score, Median frequency during endurance contraction [Hz] and both the PSQ emotional tension scale and the PSQ overall score, as well as Mean frequency during endurance contraction [Hz] and the PSQ overall score. In the second assessment within the control group, significant (p < 0.05) positive correlations were found between the following variables: Average peak amplitude during phasic contractions [µV] and both the PSQ external stress scale and the PSQ overall score; Average resting tension between phasic contractions [µV] and the PSQ emotional tension scale, PSQ external stress scale, and PSQ overall score; Average peak amplitude during tonic contractions [µV] and the PSQ external stress scale; as well as Average resting tension between tonic contractions [µV] and both the PSQ emotional tension and overall scales. Additionally, a significant (p < 0.05) negative correlation was observed between Mean frequency during endurance contraction [Hz] and the PSQ emotional tension scale. Statistically significant correlations are presented in Table 11. Detailed results of the analysis are provided in Supplementary Tables S5 and S6.

Table 11. Correlations between standardized questionnaire outcomes and pelvic floor muscles—Control group.

		R	p
Before intervention	Average peak amplitude during phasic contractions [%MVC]—before intervention & SSQ: total [sten]—before intervention	r = −0.428	p = 0.047 *
	Median frequency during endurance contraction [Hz]—before intervention & PSQ: emotional tension [sten]—before intervention	r = −0.434	p = 0.043 *
	Median frequency during endurance contraction [Hz]—before intervention & PSQ: total [sten]—before intervention	r = −0.471	p = 0.027 *
	Mean frequency during endurance contraction [Hz]—before intervention & PSQ: intrapsychic stress [sten]—before intervention	r = −0.462	p = 0.031 *
	Mean frequency during endurance contraction [Hz]—before intervention & PSQ: total [sten]—before intervention	r = −0.522	p = 0.013 *
	F ratio during endurance contraction—before intervention & PSQ: emotional tension [sten]—before intervention	r = −0.631	p = 0.002 *
	F ratio during endurance contraction—before intervention & PSQ: intrapsychic stress [sten]—before intervention	r = −0.428	p = 0.047 *
	F ratio during endurance contraction—before intervention & PSQ: total [sten]—before intervention	r = −0.539	p = 0.01 *
After intervention	Average peak amplitude during phasic contractions [µV]—after intervention & PSQ: external stress [sten]—after intervention	r = 0.509	p = 0.015 *
	Average peak amplitude during phasic contractions [µV]—after intervention & PSQ: total [sten]—after intervention	r = 0.429	p = 0.046 *
	Average resting tension between phasic contractions [µV]—after intervention & PSQ: external stress [sten]—after intervention	r = 0.459	p = 0.032 *
	Average resting tension between phasic contractions [µV]—after intervention & PSQ: total [sten]—after intervention	r = 0.574	p = 0.005 *
	Average peak amplitude during tonic contractions [µV]—after intervention & PSQ: external stress [sten]—after intervention	r = 0.438	p = 0.041 *
	Average resting tension between tonic contractions [µV]—after intervention & PSQ: total [sten]—after intervention	r = 0.482	p = 0.023 *
	Mean frequency during endurance contraction [Hz]—after intervention & SSQ:emotional tension [sten]—after intervention	r = −0.462	p = 0.031 *

Spearman’s correlation coefficient * and the red color—statistically significant (p < 0.05).

4. Discussion

The respiratory diaphragm plays a pivotal role not only in the mechanics of breathing but also in trunk stabilization, regulation of intra-abdominal pressure, and coordination of postural muscle activity [20]. In the present study, we aimed to evaluate the extent to which targeted diaphragm therapy may influence pelvic floor muscle activity, perceived stress levels, and sexual life satisfaction in women.

This relationship can be explained by the anatomical and fascial continuity between the diaphragm, the transversus abdominis muscle, and the pelvic floor muscles. The transversalis fascia originates from the cervical and mediastinal fascia and extends downward to the pubic symphysis, where it connects with the pelvic fascia. The transversus abdominis muscle, as a continuation of the endothoracic fascia, functionally links the diaphragm with the pelvic floor, forming an integrated fascial system responsible for trunk stabilization and the regulation of intra-abdominal pressure [21]. Any tension or restriction along this pathway may affect diaphragm mobility and impair the coordination between the diaphragm and the pelvic floor muscles [22]. Some studies have shown that applying manual therapy to one structure along a fascial line can have a significant effect on other structures within the same line. Likewise, Marizeiro et al. [23] reported that two sessions of manual diaphragm release significantly improved chest wall expansion, respiratory muscle strength, posterior chain muscle flexibility, and lumbar spine range of motion.

The most novel finding of this study was that the applied diaphragm therapy significantly reduced the resting activity of the pelvic floor muscles. Analysis of the results obtained from standardized questionnaires revealed that the intervention significantly reduced emotional tension and overall stress levels. In both groups, at both measurement points, a higher level of stress was associated with greater resting tension of the pelvic floor muscles, and this correlation was statistically significant.

In recent years, knowledge regarding the functioning of the PFM has expanded considerably, allowing for a more holistic perspective on the complex synergies between the PFM and respiratory mechanisms. Studies by other authors emphasize that the PFMs do not function in isolation but rather cooperate with the muscles of the anterolateral abdominal wall, and that these two muscle groups form a system closely linked to respiratory processes [3,24,25,26,27]. Moreover, the superficial and deep layers of the PFM do not always exhibit simultaneous contractile activity and can be activated separately, both during voluntary activation and during various tasks related to respiratory function [28,29,30]. Similar observations were reported by Park et al. [2], who confirmed in their studies that pelvic floor muscle contraction is associated with diaphragmatic mobility and influences pulmonary function.

Scientific literature emphasizes that breathing techniques may influence both brain function and the autonomic nervous system, which is likely one of the primary mechanisms underlying their stress-reducing effects. Appropriately selected breathing techniques increase the activity of the parasympathetic nervous system, thereby helping to balance the excessive sympathetic arousal characteristic of stress and anxiety states [31]. Moreover, the synchronization of brain rhythms with respiration promotes modulation of neuronal activity and affects mood regulation and cognitive processes [32]. Some sources highlight that, on the one hand, psychological load shapes breathing patterns [33,34,35], while on the other, an altered breathing pattern may influence the intensity of emotional experiences [36,37,38].

Hopper et al. [39], in a systematic review, concluded that diaphragmatic breathing may be a widely applicable intervention for reducing both psychological and physiological stress. Evidence presented in the systematic review indicates that diaphragmatic breathing can decrease physiological stress measured by blood pressure, respiration, and cortisol levels, as well as psychological stress assessed by the stress subscale of the DASS-21. They also noted a lack of evidence that unequivocally measures the effects of diaphragmatic breathing on stress reduction using hard biomarkers [39].

In the literature, surface electromyography (sEMG) is described as a simple and non-invasive method for assessing the PFM [14,40]. In our study, following diaphragmatic breathing therapy, a significant decrease in the resting activity of the pelvic floor muscles was observed during the final phase of the measurement protocol. In addition to assessing the ability of the PFM to relax, their activation level during phasic and tonic contractions was also evaluated. The second measurement revealed a tendency toward increased signal amplitude, indicating greater PFM activation during contractions. This change was more pronounced in the experimental group following the applied therapy than in the control group; however, it did not reach statistical significance. Studies with larger sample sizes may help to identify potential differences; therefore, further research in this area is warranted.

Several studies in the literature have investigated the hypopressive technique in relation to pelvic floor muscle function. López-Torres et al. [41] demonstrated that a structured two-month abdominal hypopressive training program significantly improved PFM strength. Other studies suggest that diaphragmatic breathing exercises may serve as an alternative to pelvic floor muscle training in the management of urinary incontinence [42,43].

In our study, the intervention protocol consisted of six sessions conducted over a two-week period (three sessions per week). This schedule is consistent with international studies on manual diaphragm therapy, in which short-term interventions have demonstrated measurable physiological and clinical effects. Rocha et al. [44] applied a manual diaphragm release technique to patients with chronic obstructive pulmonary disease and observed significant improvements in diaphragmatic mobility, inspiratory capacity, and exercise tolerance after six to eight sessions conducted over a two- to three-week period. Similarly, Cheng et al. [21] implemented a two-week intervention in individuals with chronic neck pain, achieving improvements in pain intensity, disability, and diaphragmatic function.

Analyzing the correlations between the results of standardized questionnaires and PFM activity revealed the presence of certain relationships. In the experimental group before the intervention, a positive correlation was observed between PFM activation levels and the score on the intimacy scale. A similar relationship was noted between PFM resting tension and stress level. Following the applied therapy, there was a tendency for greater PFM activation during phasic contractions to accompany higher scores on the sex scale, and for lower PFM resting tension to be associated with caressing. In the control group, both positive and negative correlations were observed, primarily concerning variables related to emotional tension and stress, although the direction and strength of these relationships were not consistent. In summary, the correlation analysis showed that in both groups, a higher level of stress was associated with greater resting tension of the PFM. This observation is consistent with previous reports indicating that PFM overactivity may represent a chronic response to stress [45].

The results of our study show convergence in certain areas with the findings of Petrelluzzi et al. [5], who implemented a comprehensive therapeutic program in women with endometriosis, combining physiotherapy with psychological intervention. This program consisted of breathing techniques, relaxation techniques aimed at reducing PFM tension, and elements of cognitive–behavioral therapy. After the eight-week program, the authors observed a significant decrease in cortisol levels, improvement in subjective vitality, as well as a reduction in pain and stress symptoms. In our study, the use of diaphragm therapy may be regarded as part of a similar approach in which regulation of muscle tension plays an important role. This effect translates not only into improved control of PFM but may also influence the psychosexual aspects of women’s lives, including perceived sexual satisfaction. The findings of Petrelluzzi et al. therefore point to potential mechanisms through which breathing techniques may support the overall improvement of women’s quality of life [5].

In our study, following diaphragmatic breathing therapy, women exhibited a reduction in overall perceived stress, particularly in the dimension related to emotional tension manifested by anxiety, nervousness, and difficulty relaxing. The decrease in emotional tension was also associated with reduced irritability, especially in interpersonal relationships, as well as with a lower sense of fatigue.

Donatti L. et al. [46] demonstrated a positive relationship between stress levels and the severity of pelvic pain in women suffering from deep endometriosis, reflecting the connection between emotional state and physiological processes.

Psychological and physiological stress are associated with a range of biochemical and physiological responses that exceed the body’s resting level. Exposure to stressors leads, among other effects, to the release of cortisol and adrenaline, increased heart rate, elevated electrodermal activity, blood pressure, and muscle tension [47]. One of the interventions used to reduce stress is breathing exercises, including diaphragmatic breathing. Experimental studies show that even a few minutes of such exercises can influence emotional state. Breathing at a rate of approximately six breaths per minute is associated with decreased arousal and an increased sense of positive energy. Prolonging the exhalation phase relative to inhalation further promotes a sense of control, relaxation, mindfulness, and stress reduction [48]. Other scientific studies likewise indicate that individuals practicing specific breathing techniques exhibit lower levels of tension and achieve mental clarity more easily [49,50].

Stress is a complex construct whose sources and consequences may take various forms. As noted by Plopa [15], its internal and external dimensions include, among others, intrapsychic, emotional, and environmental stress. A distinction between acute and chronic stress is also widely accepted. Acute stress is a short-term reaction to a sudden threat (e.g., abrupt vehicle braking), whereas chronic stress has long-term effects and negatively impacts quality of life, including functioning and sexual satisfaction [51,52]. Kanner et al. [53] emphasize that everyday minor stressors may produce more harmful health consequences than rare but more severe events. Wrześniewski, in turn, points out that it is the interpretation of a situation rather than the stressful event itself that plays a key role [54,55].

In our study, the Perceived Stress Questionnaire (PSQ) based on the cognitive–transactional theory of Lazarus and Folkman [56], in which stress is defined as a relationship between the individual and the environment, was used [56,57]. This instrument enables the assessment of subjective stress perception, understood as internal or external pressure. An analogous approach is represented by the Perceived Stress Scale (PSS) in the Polish adaptation by Juczyński and Ogińska-Bulik [58,59]. In turn, the CISS developed by S. Cohen, T. Kamarck, and R. Mermelstein and Mini-COPE developed by Charles S. Carver allow for the evaluation of task-oriented, emotion-oriented, and avoidance coping styles. In the present study, significant relationships were found between these strategies and tendencies to distort responses [57,58].

The relationship between stress and sexual functioning is bidirectional: stress hinders sexual life, and sexual difficulties increase stress levels [60]. The view that psychological stress inhibits sexual responses is supported, among others, by the studies of Bancroft [61], who points to the natural occurrence of inhibition under conditions of fatigue or emotional tension. Particularly relevant in this context is the Basson model [62], according to which the female sexual response is nonlinear and strongly conditioned by emotional and relational factors. This model emphasizes the importance of emotional closeness, relationship satisfaction, and openness to sexual contact even in the absence of spontaneous desire. Consistent with Basson’s framework, our findings indicate that women’s sexual functioning is more susceptible to emotional burden and perceived stress than to purely biological factors [62].

In the control group, no significant relationships were found between stress dimensions and sexual satisfaction. In contrast, among women undergoing therapy, higher levels of worry, decreased sense of life meaning, low agency, and pessimism correlated with lower sexual satisfaction and difficulties in achieving orgasm. These findings partly reflect the observations of Kanner et al. [53], which emphasize the importance of minor, everyday stressors. Furthermore, in this group, a tendency to lie or present oneself in a favorable light was observed, which can be interpreted as a manifestation of avoidance or emotion-focused strategies. This possibility should be taken into account when interpreting the results, particularly with regard to the dimensions of emotional closeness and caressing.

The obtained results are consistent with the findings of Bodenmann et al. [63], who demonstrated that higher levels of daily stress in women correlate with a greater number of sexual problems and lower sexual satisfaction. Similar conclusions were presented by Ter Kuile et al. [64], who showed that women with high stress levels experienced lower genital arousal, although they did not differ from others in terms of psychological arousal. This mechanism can be explained by the cognitive consequences of stress—distraction and a limited ability to focus on erotic stimuli [65]. In our study, a negative correlation was also found between daily stress, sexual satisfaction, and genital arousal.

Several limitations of the present study should be noted. First, although the required minimum number of participants was met, the sample size was relatively small, which may have limited the ability to detect the effects of the therapy. The study is probably underpowered to identify moderate differences. Furthermore, no assessment of the long-term effects of the therapy was conducted, which would certainly be valuable for evaluating the effectiveness of the applied intervention. Another limitation of the study is the short duration of the therapy and the lack of assessment of the long-term sustainability of the observed effects. A total of six therapeutic sessions were conducted over a two-week period. It is possible that extending the duration of the therapy could have resulted in additional beneficial effects in the experimental group. In future studies, follow-up assessments are planned at 1 and 3 months to determine whether the beneficial effects are maintained over time. Another limitation of the study is the relatively narrow inclusion criteria. On the one hand, this selection allowed for the formation of a homogeneous group, thereby increasing the reliability of the obtained results. However, restricting the study group to such specific criteria limits the generalizability of the findings to other populations. Further research is needed in this area, including studies involving other groups, such as women with stress urinary incontinence or those in older age categories. Another limitation of the present study is the absence of a sham or placebo control group. The lack of a sham group may have influenced subjective outcomes, particularly those related to perceived stress levels and satisfaction, which should be considered when interpreting the results. Another limitation of the present study is the lack of a direct assessment of diaphragmatic mobility, for example, using ultrasonography. Although surface electromyography (sEMG) provides valuable information on muscle activity, it does not allow for the direct evaluation of diaphragm displacement or its mechanical efficiency. Future studies should consider employing objective tools for assessing respiratory function, such as ultrasonography or spirometry, to obtain a more comprehensive understanding of diaphragm function and its relationship with pelvic floor muscle activity.

Another limitation of the present study is the lack of complete blinding of the participants. Although the assessor performing the measurements was blinded to group allocation, the participants were aware of whether they were receiving the intervention, which may have influenced their responses. An additional limitation is that only healthy, asymptomatic women were included, which limits the generalizability of the findings to clinical populations. The inclusion of women without urogenital or musculoskeletal disorders allowed for the formation of a homogeneous sample and minimized potential confounding factors. Another limiting factor is the lack of control over the menstrual cycle phase of the participants, which may have affected both physiological and psychological parameters, including stress and satisfaction levels. Furthermore, future studies should consider the potential influence of cultural and social factors on the interpretation of results obtained using psychometric tools such as the SSQ and PSQ. Moreover, it should be noted that no correction for multiple testing was applied to the analyses based on questionnaire data, which increases the risk of type I error. Therefore, these findings should be interpreted with caution. Another limitation of the study is the lack of multivariate analysis to adjust for potential confounding factors. However, the experimental and control groups were comparable at baseline in terms of age, body mass, height, BMI, education level, type of relationship, and relationship duration, which likely minimized the influence of these variables on the results.

Despite the limitations of the study related to sample size and the lack of long-term follow-up, the results indicate the clinical potential of diaphragm therapy as a complementary physiotherapeutic method supporting both psychophysical health and women’s sexual quality of life. The obtained findings suggest that diaphragmatic breathing therapy may help improve PFM activity. Further studies on larger populations are necessary to clearly determine the clinical potential of this method in physiotherapy practice.

5. Conclusions

The findings of the present study suggest that therapy targeting the respiratory diaphragm reduces the resting activity of the PFM and perceived stress levels, particularly in the emotional dimension. The observed association between higher stress levels and greater resting tension of the PFM suggests a bidirectional relationship between emotional state and physiological functioning. Further research in this area is certainly needed to confirm these effects.

From a clinical perspective, diaphragm-focused therapy may serve as a valuable adjunct to physiotherapeutic interventions aimed at reducing pelvic floor muscle activity as well as stress-related tension in women. Integrating diaphragmatic techniques into pelvic floor rehabilitation programs could further enhance therapeutic effectiveness.