The female pelvic floor is a complex structure highly vulnerable to diversified events of women´s life [1]. The lesions that occur to pelvic floor muscle arising from women's life events can lead to incontinence, constipation, decreased or lack of muscle strength and genital prolapse, which generates impact on quality of life [2]. For this reason, a proper assessment of the function, strength and integrity of PFM has a special role in diagnosing and treating disorders involving this region [3]. A strength assessment may give evidence to the status of muscle weakness severity, in addition to being essential for designing specific exercise programs, as well as for monitoring rehabilitation progress. Therefore, the objective this study is to compare the values of manometry among the age groups in adult women.

It was realized a cross sectional. The sample consisted of 228 women divided to three groups: Group A: women with 40 – 50 years (n = 70); Group B: 51 – 60 years (n = 75); Group C: 61 – 74 years (n = 79).  The sample was the result of a non-probability sampling process. The study included women without an intact hymen, with no urinary, vaginal infection or gynecological bleeding, and who had not had deliveries or gynecological surgery performed for at least six months. It was used the Peritron 9300V (Cardio Design, Australia) to measure the pression of pelvic floor muscle. To perform the manometry, the volunteer remained in a gynecological position with knees flexed, hips flexed and abducted, and was naked from the abdomen down. The patients were instructed on the correct way to contract PFM, dissociating from abdominal muscles, hip adductors and glutes. The volunteer was also instructed to breathe normally, avoiding the Valsalva maneuver, and to perform muscle contraction with the greatest strength possible. Volunteers were also instructed to empty their bladders before the manometry. The vaginal probe was covered with a non-lubricated latex condom. A lubricating gel was used for insertion into the vaginal cavity. The probe was inserted with the equipment turned off. Three maximum voluntary contraction of PFM was requested, with two to three seconds of duration each. The command was "squeeze the probe". Was stablished an interval of 30 seconds of  rest between the muscle contractions [4]. The device was reset to zero for each contraction. The assessment was performed by a single evaluator, physiotherapist expert in PFM function assessment. For the analysis, was considered the average of the three squeezes and it was used the classification scale of manometry: Very Weak (7.5 – 14.5 cmH2O), Weak (14.6 – 26.5 cmH2O), Moderate (26.6 – 41.5 cmH2O), Good (41.6 – 60.5 cmH2O) and Strong (> 60.6 cmH2O) [5]. To compare the age groups and manometry was used the Anova. The study was approved by the Ethics Committee.

The three groups were homogeneous in sociodemographic characteristics, except for age. Anthropometric measures, such as body mass index and waist circumference, showed no intergroup difference (p=0.64 and p=0.53, respectively). Obstetric history revealed homogeneity between the three groups in relation to pregnancies and number and type of deliveries. There was no statistically significant difference in the manometry mean between the age groups (p = 0.68). The mean of manometry between the age groups is shown in the Table 1.

Our results do not indicate statistically significant differences among women of different age groups. It is known that the natural aging process causes a stretch in the tissues. Histological analysis of cadavers showed that pelvic floor tissue of the elderly was more rigid and less elastic, irrespective of previous trauma suffered [6].
It is important to note that it was analyzed data from women over 40 years of age. It is believed that the functional decline in this population is due to hormonal changes and the natural female aging process [7]. The muscle mass loss process starts around the age of 40 years and is accompanied by reduction in the cross-sectional area, diminished strength, and changes in muscle composition caused by fat deposition, resulting in diminished functionality known as sarcopenia. In women, this occurs simultaneous to changes in menopausal status, making it more difficult to differentiate between the purely hormonal influence and the influence of the aging process [8]. It is known that there is a positive correlation between the systemic levels of estrogen and indicators of muscle quality and strength. There is one study that showed a strong positive correlation between tonus and maximum voluntary contraction in the PFM and an increase in estradiol level [9].
Histological analysis revealed that during the sarcopenia process there is preferential loss of type II muscle fibers and conversion of type II fibers into type I, causing a negative impact on muscle strength and power[10]. These muscle changes would therefore be responsible for the decline in PFM function in women over 40 years.

It was concluded that there is not difference on pelvic floor muscle pressure in  women over 40 years. There are strong indications in the literature that advancing age is associated with a decline in PFM function and that this is common to all women.

Angelo PH, Varella LRD, de Oliveira MCE et al. A manometry classification to assess pelvic floor muscle function in women. PLoS One. 2017 Oct 30;12(10):e0187045.
Slieker-ten Hove MC, Pool-Goudzwaard AL, Eijkemans MJ, Steegers-Theunissen RP, Burger CW, Vierhout ME. Pelvic floor muscle function in a general female population in relation with age and parity and the relation between voluntary and involuntary contractions of the pelvic floor musculature. Int Urogynecol J Pelvic Floor Dysfunct. 2009;20(12):1497-1504.
Bø K, Sherburn M. Evaluation of female pelvic-floor muscle function and strength. Phys Ther. 2005;85(3):269-282.