Falls and urinary incontinence (UI) are major issues affecting older women age 65 and over. Urgency and mixed UI are independently associated with an increased risk of falls in older women (1). Bladder distension is hypothesized to be associated with increased trunk muscle activity (2). However, the relationship between urgency UI, and trunk and pelvis movements during gait is still not well understood. The objective of this study is to investigate the effect of an urgent desire to void (UDV) on trunk and pelvis movement during an assessment of gait kinematics in older women with urge/mixed UI, who had experienced falls.

An observational pilot study was undertaken with two groups of healthy community-dwelling women age 65 and over, who experienced at least one fall in the last 12 months. Participants included in the urinary incontinent group had moderate to severe urge/mixed UI, as determined by the International Consultation on Incontinence Questionnaire on UI Short Form (ICIQ-UI SF), and >3 urine leakages/week in the 7-day bladder diary (with at least one urgency-related leakage). Participants in the continent group had an ICIQ-UI SF score equal to 0, no urine leakage reported in the past year and none in the 7-day bladder diary. Participants with a body mass index (BMI) >35 and health conditions likely to influence gait during the study were excluded. After signing a consent form and completing a 24-hour pad test, each participant partook in the experiment. Demographic data, history of falls and the results of the Montreal Cognitive Assessment test (MOCA) were collected for all participants. Participants’ gait kinematics were assessed using a Northern Digital Inc. Certus motion analysis system with markers placed on the participants’ feet, shanks, pelvis and trunk, and a Bertec Fully Instrumented Treadmill (dual belt). The participant self-selected the gait speed, which was determined with no desire to void, and kept identical for all experimental trials. Participants drank water until they reported feeling an urgent desire to void (UDV), which was determined by a score of 3 on the Urinary Sensation Scale (USS). Participants were then asked to walk on the treadmill for 20 consecutive gait cycles then to go to the toilet. Immediately after emptying their bladder, the participants (with no desire to void (NDV)) were asked to walk again on the treadmill for 20 consecutive gait cycles. The mean and standard deviation (SD) of the gait parameters (treadmill gait speed, stride length and width) and of the total amplitude of trunk and pelvis movements (as measured by the trunk center of mass in the antero-posterior and medio-lateral positions [T COMAP/ML] and by pelvis center of mass in the antero-posterior and medio-lateral positions [Pel COMAP/ML]) were calculated for both groups. Descriptive statistics were obtained for demographics, cognitive and UI status, gait, and trunk and pelvis movement data. Independent t-tests and chi-square tests were used to compare the continent and UI groups for demographics, as well as cognitive and incontinence outcomes. An analysis of variance (ANOVA) with two factors and repeated measures was conducted to explore the differences between the two groups (continent and UI) for the two conditions (NDV and UDV). The p-value threshold was 0.05 and SPSS v24 was used for statistical analyses.

Thirty women participated in the study; 16 were continent and 14 had urgency/mixed incontinence. Both groups were similar in terms of age (74.6 years (4.1) and 73.5 years (5.9)) and MOCA scores (27/30 (3) and 28/30 (3)), respectively. BMI, number of falls, ICIQ-UI SF scores and number of urine leakages noted in the bladder diary were significantly different between groups, favoring the continent group. 

There was a statistically significant interaction effect between groups (continent and incontinent) and bladder condition (NDV and SDV) for trunk and pelvis center of mass mediolateral movement (T COMML, F=5.92, p=0.02 and Pel COMML, F=8.17, p=0.00) with less displacement in the mediolateral direction of the trunk and pelvis during gait, in the incontinent women when experiencing UDV (Table 1). 

For gait parameters, there was no interaction between groups and bladder condition. However, study groups were different in terms of stride length, with those with incontinence having smaller stride length F=4.64, p=0.04 and larger step width, F=4.48, p=0.04 (Table 1).

In the UDV condition, there was less change in trunk and pelvis movements for incontinent women than in continent women. This suggests an increase in trunk and pelvis ‘stiffness’, possibly to increase pelvic floor and trunk muscle activity. However, this trunk and pelvis stiffness may also result in reduced posture correction capacity and eventually higher risk of falls (3). 

Women in the incontinence group had a smaller stride length and a larger step width, which is in line with their specific walking speed.

This is the first observational study of urinary incontinent and continent community-dwelling women who have experienced falls to report the influence of UDV on trunk and pelvis movement during gait at a fixed walking speed. UDV appeared to affect trunk and pelvis mediolateral displacement during gait differently in incontinent and continent older women at risk of falls. The incontinent group reduced movement of the trunk and pelvis, which appeared stiff, possibly to activate pelvic floor and trunk muscles to avoid leakage. More studies on the pelvic floor muscles using abdominal electromyography recording, in addition to rigidity tools, are necessary to confirm these results and to further understand the relationship between trunk and pelvis displacement and falls in a population of incontinent older women.

Chiarelli PE, Mackenzie LA, Osmotherly PG. Urinary incontinence is associated with an increase in falls: a systematic review. Aust J Physiother. 2009;55(2):89-95.
Castroman P, Ness TJ. Vigor of visceromotor responses to urinary bladder distension in rats increases with repeated trials and stimulus intensity. Neurosci Lett. 2001;306:97–100.
Smith MD, Coppieters MW, Hodges PW. Is Balance Different in Women With and Without Stress Urinary Incontinence? Neurourol. Urodynam. 2008;27:71–78.