What Transient Effects Does the Performance of a Hypopressive Exercise Have on Intra-Abdominal Pressure and on Pelvic Floor Muscle Activation in Females?

Abstract

The gold standard to treat mild to moderate urinary incontinence (UI) and pelvic organ prolapse (POP) in women is pelvic floor muscle training (PFMT). However, hypopressive exercises (HEs), a postural and respiratory exercise approach first described by Caufriez in 1997 (Caufriez, 1997) have gained popularity around the world as an alternative or adjunct to PFMT in the treatment of pelvic floor disorders (PFDs). The theoretical aim of HEs is to decrease intra-abdominal pressure (IAP), which supposedly leads to activation of the abdominal and pelvic floor muscles (PFMs) through reflex mechanisms. However, these proposed phenomena have not been studied empirically. The objectives of this cross-sectional, observational study were (1) to investigate the acute, transient effect of HEs on IAP and abdominal and PFM activation in females, (2) to determine the relative importance of the postural maneuver and respiratory apnea components of HEs on the transient effects of these exercises on IAP and on abdominal and PFM activation, and (3) to determine whether any effects of the HEs on IAP or abdominal or PFM activation were more marked after six to eight weeks of training. Thirty-six healthy participants with female-typical pelvic anatomy, who were naïve to HEs were recruited from the local community via flyers, advertisements, and word of mouth. Participants attended an initial training session, a follow-up session one week later to ensure the exercises were performed correctly, and the first data collection session two weeks after the initial training session. Twenty-four of these participants were invited and agreed to continue the HE training for an additional six to eight weeks prior to attending the second data collection session. The two data collection sessions were the same. The primary outcome measures included the magnitude of change in IAP (measured by an intravaginal sensor), activation of the PFMs (measured using electromyography (EMG)), and changes in the levator plate length (LPL), the bladder neck height (BNH) and the levator plate angle (LPA) relative to horizontal observed through transperineal ultrasound video clips recorded during the HE maneuver performed with and without the HE posture. The IAP did not decrease significantly during the HE in either visit [supine or standing; with or without hypopressive posture (HP)]. The PFMs and abdominal muscles were active during the first [levator ani muscles (LAMs): 44(35)%MVC (supine) to 50(44)%MVC (standing); external anal sphincter (EAS): 27(24)%MVC (supine) to 27(27)%MVC (standing); [external oblique (EO): 21(13)%MVC (supine) to 36(31)%MVC (standing); internal oblique/transversus abdominis (IOTrA): 58(55)%MVC (supine) to 64(48)%MVC (standing)] and second [LAMS: 71(55)%MVC (supine) to 72(75)%MVC (standing); EAS: 45(52)%MVC (supine) to 35(34)%MVC (standing); EO; 34(41)%MVC (supine) to 52(75)%MVC (standing); IOTrA: 58(65)%MVC (supine) to 80(73)%MVC (standing)] data collection sessions. The pelvic floor morphology changed during the HE maneuver at both data collection sessions, suggesting the PFMs were active concentrically ([LPL (-2.2mm supine, η_p^2 = 0.08, p=0.18; -4.4mm in standing, η_p^2 = 0.12, p=0.10); BNH (0.2mm in supine, η_p^2 = 0.02, p=0.48; 0.3mm in standing, η_p^2 = 0.00, p=0.90), LPA (2.4° in supine, η_p^2 = 0.02, p=0.46; 1.0° in standing, η_p^2 = 0.11, p=0.12)]. There was no effect of body position or the HP on any outcomes at either visit. The training period of six to eight weeks did not result in any learning effect in terms of the exercise mechanism as theorized by Caufriez, and there was no increase in PFM voluntary contraction strength. Therefore, the theory proposed by Caufriez regarding the mechanism of action of the HEs is not supported by this cross-sectional study, nor does it corroborate the effectiveness of HEs in improving the contractile force or tone of the PFMs.