Background: Prolonged standing has been associated with an increased prevalence of low back pain (LBP) and is recognized as a potential workplace hazard for employees such as retail staff, assembly line workers, and healthcare personnel. Low back pain is more prevalent in women than in men, and disability due to LBP is worse in women with severe urinary incontinence. However, it is unclear whether pelvic floor dysfunction observed in stress urinary incontinence is a risk factor for LBP. The main purpose of this study is to determine whether co-activation patterns between the pelvic floor and abdominal muscles during a 2-hour prolonged standing task predict transient LBP in women with and without stress urinary incontinence.
Methods: In this is prospective cohort study, 60 female volunteers will stand in a confined area for 2 hours (120 minutes) while performing tasks such as, 'computer work' and 'small object assembly'. The primary outcome measure is transient LBP, which will be monitored every 10 minutes using a numeric pain rating scale. Surface electromyography (EMG) will be collected from the gluteus medius and internal oblique/transverse abdominis muscles, and an intravaginal electrode will be used to monitor pelvic floor muscle activity. The EMG signals will be divided into 12 10-minute blocks to assess changes in co-activation over time. Cross-correlation analyses will be used to quantify co-activation between the muscle pairs (e.g. pelvic floor and internal oblique/transverse abdominis), and the coefficient of co-activation will be expressed as a percentage for each block. A mixed-model regression analysis will be used to determine whether co-activation patterns can predict transient LBP during the prolonged standing task.
Discussion: The primary objective of this research is to improve current understanding regarding the role of pelvic floor muscles in the onset of LBP and the potential association between stress urinary incontinence and LBP. These findings have the potential to inform prevention and rehabilitation programmes for women with stress urinary incontinence and LBP.
Trial registration: ACTRN12618000446268 [Protocol Version 2].
Keywords: low back pain; pelvic floor; prolonged standing; urinary incontinence.