Our study demonstrated that an eight-week period of cPFM-T with forced exhalation, performed by young nulliparous women in both the supine posture and the sitting posture, using trunk muscle synergies, is effective in improving cases of incontinence.
Furthermore, the holding period, rapid reaction and resting function of the PFM—as well as the thickness of TRA—improved due to both the modification of body position and the exhalation technique. Improvements in the holding function of the PFM were significant in both the supine position and the sitting position, but improvements in the rapid reaction of the PFM were significant only in the supine position, while those in the resting function of the PFM were significant only in the sitting position. The thickness of the TRA improved in both the supine position and the sitting position.
Assessments of the PFM can be used to determine which structural or functional features are deficient, and to inform the design of subsequent training regimens to address these dysfunctions. A diversity of exercises, possibly tailored to the abilities of each woman, may be used and proposed training includes raising the number of repetitions of contractions [24]—a recommendation endorsed by our results.
Sapsford [23] advocated a new approach to the rehabilitation of urinary incontinence—motor relearning for diaphragmatic, deep abdominal muscles and the PFM rather than selective muscle strengthening.
Thompson et al. [25] suggested careful monitoring of Sapsford’s complex rehabilitation training, because abdominal muscles are more active than PFMs in symptomatic women. These results suggest that a coordinated approach involving both deep abdominal muscles and PFM is necessary.
The correct breathing technique is very important in PFM-T. The diaphragm is a respiratory muscle participating in the stabilisation of the lumbar spine by enhancing abdominal pressure [26], which in turn stabilises the lumbar spine. Hodges et al. [27] reported synergism between the diaphragm and the TRA. We also utilised this synergism by forced exhalation in our study.
Neumann and Gill [6] suggested that the activation of deep abdominal muscles is essential for an effective contraction of the PFM, because their continent participants were unable to contract the PFM effectively while maintaining relaxation of the TRA and the IO. Similarly, Madill and McLean [22] found that the patterns of abdominal muscle activity appear to occur due to voluntary PFM contractions in healthy continent women.
As a representation of vaginal closure force, the isometric contraction was considered to be greater in the supine than in the standing position. Subsequent studies, however, have determined that women are able to perform equally strong PFM contractions in either body position [7, 8, 11].
The PFM is a striated muscle, with two thirds of its fibres are type I (slow-twitch fibres), responsible for the resting tone of the levator muscle and one third of its fibres, type II (fast-twitch fibres), responsible for sudden, fast but powerful contractions. The activity of the slow fibres is necessary for the resting potential and the retention of urine and stool, while the fast fibres are responsible for resistance during sudden abdominal pressure [28]. We monitored the activity of these two fibre types (retention and rapid function) in our study with vsEMG measurements and trained both types in weaker and stronger PFM-T.
The fact that SUI happens most frequently in the upright position informed our study of the functional (static and dynamic) parameters occurring in everyday life. The holding function of the PFM is important for the patients—that is, they need to be able to get to the toilet in time before their urine starts leaking. The quality of breathing plays an important role in PFM training. It is necessary to teach participants the correct abdominal breathing technique which activates the TRA. In our study, we activated the TRA and voluntary contraction of the PFM with strong exhalation techniques during both measurements and training. Using biofeedback (TRA ultrasound imaging and vsEMG curves of PFM) we visualised the co-contraction of the two muscles with the participants. Our vsEMG findings indicate that the static isometric contraction force of the PFM increased significantly in both study groups—and the holding time of static isometric contraction of the PFM increased slightly—with forced exhalation. In the COG, the static strength of the PFM increased slightly, but this increase was not significant and was characterised by a short retention time. The thickness of TRA during maximal isometric contraction of the PFM till fatigue improved in both training groups, but in neither group was this improvement significant. The COG claimed that this parameter decreased significantly because, during our study, they had spent much more time in a sitting position and were therefore in an enforced inactive lifestyle. Another study obtained similar results for musculus multifidus [29].
Hung et al. [14] 2010 investigated the effects of combining voluntary PFM- and deep abdominal muscle training in different body positions. The TRA activity was significantly greater in the sitting and standing positions than in the supine position. Chmielewska et al. [11] also reported that long-lasting contractions in the unsupported sitting position utilised the sensorimotor control system significantly compared with those in the supine position. However, in our study, cPFM-T in both the weaker PFM (in the SUG) and the stronger PFM (in the SIG) led to significant development in long-lasting contractions regardless of the body position of the measure.
Chmielewska et al. [11] measured the rapid activity of the PFM with vsEMG in the supine position and in the sitting position, finding no significant differences between the PFM average peak amplitudes in the investigated positions, while we found these values to be significantly improved in the supine position. In our study, only in the supine position did the strength and repetition of dynamic fast contractions increase\ significantly; in the sitting position, changes in dynamic fast contractions were not significant. The fast activity of the PFM is responsible for resistance during sudden abdominal pressure. In the COG, dynamic strength and repetition decreased and did not manifest significant changes.
Capson et al. [8] and Chmielewska et al. [11] measured the relaxation tone of the PFM in the supine position and in the sitting position. They deduced that gravity forces increase the pressure on the PFM in the vertical position, increasing its tone and leading to a higher resting activity of the PFM in the sitting position than in the supine position. During our measures, the SIG participants found it easier to relax in the horizontal position. Based on our results, practising relaxation exercises can be beneficial not only in the horizontal position but also in the vertical position. Improvement in the relaxation ability of the PFM is also a beneficial result, because especially during urination, for a healthy, normal urination mechanism it is necessary to consciously relax the PFM. The relaxation state of the PFM improved significantly due to gravity forces only in the SIG.
We observed that the conditioning capabilities of the PFM improved in the SUG during the 8 week period of cPFM-T. The ability to sustain isometric contractions improved significantly, while holding time also improved, but this improvement was not significant. There was also a significant improvement in dynamic endurance and repetitions. Therefore we recommend a more intense strengthening of the TRA in the horizontal body position.
In the case of the SIG, the maximal isometric contraction of the PFM till fatigue also improved significantly, together with the holding time, but the latter improvement was not significant. The dynamic endurance decreased and the number of repetitions improved slightly, but these changes were not significant. The relaxation state of the PFM improved significantly due to gravity forces. The resting tone of the TRA remained unchanged after 8 weeks. Thus, even more intense TRA activation is required in the vertical position, as a reliance on the enhanced gravitational forces caused by the lumbopelvic posture or on the activated TRA induced by strong exhalation is insufficient to induce the necessary changes in the functioning of the TRA.
In the case of the COG, all parameters decreased—particularly the thickness of TRA during maximal isometric contraction of the PFM till fatigue, which decreased significantly—by reason of sedentary lifestyle.
We also established that young nulliparous women might also be affected by urinary leakage (27%) as confirmed by the results of Haslam et al. [1].
In the case of the SUG, both training exercises and measurements were performed in the supine position, whereas the SIG participants were measured in the lying position but performed all the exercises in the sitting position. Since SUI takes place most frequently in the vertical position, we should not measure and strengthen the static and dynamic functions of the PFM only in the supine position. We recommend that during cPFM-T, isometric and relaxation tasks should be performed both in the supine position and in the sitting position.
According to Sapsford et al. [5], the antigravity posture requires more intense PFM activity. Furthermore, Chmielewska et al [11] reported a significant difference between the sustained 1-minute contraction of the PFM in the supine position and that in sitting position, while we found that the maximal isometric sustained contraction of PFM till fatigue significantly improved both in the supine position and in the sitting position.
Group training and individual training, according to recent research, are equally effective, and group training is more cost-effective without limitation[30]. Furthermore, due to differences in knowledge and behaviour, physiotherapist-guided training can help and motivate patients in persistent PFM-T [31].