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Research Studies

Prevalence study of stress urinary incontinence in women who perform high-impact exercises

Celina Fozzatti C , Riccetto C, Herrmann V, Brancalion MF, Raimondi M, Nascif CH, Marques LR, Palma PP. Int Urogynecol J 2012; 23: 1687-1691.

Why they did the study

Several recent studies have shown a relationship between stress urinary incontinence [SUI] symptoms and the performance of high-impact physical activities in women as a result of direct damage to the pelvic floor. The objective of this study was to evaluate the prevalence of SUI in women who attend gyms and perform high-impact physical exercises and compare this with those who do not.

How they did it

This was a cross-sectional, case-control and community-based study carried out in Brazil on 488 healthy, sexually-active and nulliparous women between 20 and 45 years of age. The participants were subdivided into two groups: study, consisting of 244 women who attend gyms and control, consisting of 244 women who do not go to gyms or perform any high-impact exercises. Women with diabetes mellitus, chronic lung diseases and those who had undergone previous surgery for SUI, have a urinary tract infection or with a body mass index exceeding 30 were excluded. The criterion to classify the type of exercise as high-impact was weight-bearing lower extremities exercise including jumping and leaping in vertical and onward directions. All other exercise was considered non-high impact.

All women were interviewed in the community using 3 questionnaires: personal information form; the International Consultation on Incontinence Questionnaire Short-Form [ICIQ-SF] to evaluate SUI symptoms and specific questionnaire about the physical activity with type and frequency of exercise and the relationship between urine loss and the activity.

The sample size was calculated based on the expected average score calculated from the ICIQ-SF, assuming an average difference of 0.81 between the groups and a significance level of 5% (alpha or error type I) and a power of 80% (beta or error type 2 of 20%).

What they found

The study and control group were comparable in the various demographic parameters. The average age was 25.6 years in the study group and 24.5 years in the control group. There was a significant difference between groups (p = 0.006) regarding the ICIQ-SF. The average score was 1.68 (+ 3.46) in the study group and 1.02 (+ 2.69) in the control group. When comparing the replies to the last question of the questionnaire, in which the loss of urine during effort and the situation of the loss was evaluated, 24.6% of women in the study group reported loss of urine compared with 14.3% in the control group (p = 0.006). There was also a significant difference reported between the groups regarding the question in which the respondents were asked if loss of urine occurred during physical activity: 5.7% in the study group compared with 0.4% in the control group (p = 0.001).

In the study group, 57.4% of women reported emptying the bladder as prevention before starting the exercises. Regarding the type of exercise, jumping was the cause of urine leakage in the highest number of women.

Why it matters

Physical activity has been promoted to all ages because of the benefits to health and as a tool to compensate for a sedentary lifestyle which can result in obesity, muscle weakness and postural problems. With this objective in mind, men and women exercise at gyms, without paying too much attention to the fact that during the execution of the activities, the superficial muscles as well as the internal muscles are engaged and could be damaged in the event that the exercises are not properly done.

The pelvic floor muscles [PFM] are part of the musculo-skeletal system around the sacroiliac joint that contributes to the stabilization of this region as well as of the lumbar spine. Additionally, these muscles also have the function of keeping the viscera inside the abdominal cavity, and in women, contribute to sphincter functions. With increased abdominal pressures, the PFM contraction exerts a pull on the anterior vagina wall toward the pubic symphysis leading to the occlusion of the urethra and preventing urine leakage. This mechanism is called upon during physical exercises when there is a variation in the intra-abdominal pressure. The PFM activity can be compromised if these muscles are damaged and their dysfunction is one of the factors involved in the development of SUI in women. Rupture of the endopelvic fascia or the arch tendinous insertion of the pelvic floor muscles may result from high-impact physical activities. Fatigue of the PFM may also occur from repetitive muscular contraction during high impact exercises. Another possible mechanism is the changes in physiological curvature of the spine leading to postural changes and modification of the structure of the pelvic cavity with stretch/ compression injury of the PFM.

This large study has clearly shown a high prevalence of SUI amongst women who perform high-impact physical exercises similar to previous reports in elite athletes and ballet dancers. These findings are more significant because the study cohort was young, nulliparous, non-obese and healthy and therefore did not have potential risk factors for developing SUI. It is possible, however, that interviewing women in the community is responsible for this relatively high prevalence of SUI because the majority of incontinent women do not usually seek health care. A further interesting finding was the high prevalence of SUI in the control group (14%) and the overall high prevalence of SUI (39.4%) in this study population. This supports the increasing community prevalence of SUI in women of all ages.

This study, however, was cross-sectional and not adequately controlled because the study and control groups were not matched. The technique of sampling is also not known and this may have introduced a selection bias. Further longitudinal, properly randomized and matched case-control studies are needed to verify these findings.

Next question

Stress urinary incontinence is a prevalent complaint in women responsible for approximately 50% of urinary incontinence symptoms observed in clinical practice amongst women between 25 and 45 years old. It is widely believed that stress incontinent women abandon physical activities for fear of precipitating an incontinence episode. There is increasing evidence in the literature that the relationship between SUI and physical activity is more complicated because of the reported high prevalence of SUI in female athletes and in women performing high-impact exercise. Misguided heavy exercise can be as important as other traditional risk factors for SUI such as pregnancy, childbirth, obesity and ageing, because of possible damage to pelvic floor muscles. It is important to understand that this may affect female non-athletes who represent the biggest part of society and who may try to compensate for the lack of physical activity by going to gyms and practicing exercise often without guidance and without special precautions to protect and strengthen their PFM. This information should be clearly communicated to women by public and incontinence health care providers.

Further research should identify which type of exercise, time and frequency of practice and specific physical activity are mainly responsible for SUI. The findings could be used to counsel women in gyms and sports centers as well as in family practice clinics. More importantly, functional anatomy and biomechanical studies of the female pelvic floor components should improve our understanding of the mechanism and threshold of physical exercise- induced injury to the pelvic floor with a potential for planning safer sports programs. Epidemiological data are urgently needed on the factors responsible for the development of SUI in the presumed low-risk subgroup of young, lean and nulliparous women.

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