No significant differences were found between groups of overweight and obese women regarding the type and severity of UI, on the 1-hour pad test and in the steps power, endurance, and repetition for PERFECT; however, it was found that the OWG obtained a better PFM contraction of fast fibers.
Obesity may result in increased IAP, compromising PFM integrity, damaging nerves, muscles, and connective tissue, resulting in urethral hypermobility20. Furthermore, obesity causes descent and rotation of the bladder neck and part of the urethra, changing the pressure gradient and generating urine leakage20, justifying the most frequent type of UI was that the SUI in both groups.
The urge-incontinence may happen in obese women due to a reduced amount of the hormone ghrelin20. This hormone inhibits the detrusor muscle contractile response, bringing adverse effects on urinary control20. The decreased ghrelin may result in increased detrusor muscle contractile response in obese women, causing urgency and urge incontinence.
The prevalence of UI does not only occur in obese women. According to the study21, overweight women are 2.7 times more likely to have UI than those with normal weight. This study may justify the fact that the severity of UI, the pad test, the contraction capacity and resistance of PFM, and the QL in the present study did not present a significant difference between obese and overweight women.
Other studies have verified the association of the severity of UI with PFM strength, where lower force would result in a urethral closure deficit and higher UI severity, and may be associated with poorer QL22,23. The majority of the women in the present study had moderate or severe UI in the OWG and moderate or very severe UI in the OG. In both groups this had a negative impact on the QL, highlighting this possible association between the severity of UI and the QL.
The OWG presented better contraction of the PFM fast fibers than the OG, corroborating the fact that weight gain is considered a risk factor for SUI, in which the fast fibers do not contract effectively8,24. Another’s studies comparing overweight and obese individuals with lean subjects identified a reduction in the percentage of oxidative muscle fibers and increase in glycolytic25, but another study showed no change26.
These controversial results which are presented in the literature may be influenced by genetic and ethnic factors25,26 which also influence the function of PFM, and so there is a limitation in justifying the obtained results. This is because our results indicate a worse contraction capacity of fast fibers in the OG, which besides being associated with increased IAP may also have other influencing factors which have not been evaluated.