Aims: Impact activities like running are known to elicit symptoms of stress urinary incontinence (SUI). The aim of this study was to investigate and compare pelvic floor muscle activity in continent and SUI women during running at three different speeds and thereby elucidate contraction characteristics of the pelvic floor during impact.
Methods: Surface electromyographic (EMG) activity from the pelvic floor muscles during running on a treadmill was recorded with a tripolar vaginal probe. EMG was measured during 10 s at the speeds 7, 11, and 15 km/h. Data from 30 ms before to 150 ms after heel-strike were parameterised to time intervals of 30 ms. The reference value set as 100% for EMG normalisation was calculated as the mean of the peak values of two maximum voluntary contractions.
Results: No statistically significant differences between continent and incontinent subjects could be found for the EMG values for all time intervals. Mean EMG pre-activity and reflex activity increased significantly with speed (P < 0.05). Mean EMG activity during running was significantly above PFM onset activation. Values in women with SUI exceeded 100 %MVC for all time intervals at the highest speed of 15 km/h.
Conclusions: Running appears to trigger pre-activation before and reflex-activation after heel-strike and should therefore not only be regarded with caution due to its SUI related effects. Running training stimuli may serve as a beneficial complement to a PFM training rationale, leading to reflex activity of the pelvic floor muscles, when used in sense of power training methodology.
Keywords: activation; electromyography; high impact; pre-activity; reflex-activity; speed.
© 2016 Wiley Periodicals, Inc.