Intra-session test–retest reliability of pelvic floor muscle electromyography during running

Abstract

Introduction and hypothesis The prevalence of female stress urinary incontinence is high, and young adults are also affected, including athletes, especially those involved in "high-impact" sports. To date there have been almost no studies testing pelvic floor muscle (PFM) activity during dynamic functional whole body movements. The aim of this study was the description and reliability test of PFM activity and time variables during running. Methods A prospective cross-sectional study including ten healthy female subjects was designed with the focus on the intra-session test-retest reliability of PFM activity and time variables during running derived from electromyography (EMG) and accelerometry. Results Thirteen variables were identified based on ten steps of each subject: Six EMG variables showed good reliability (ICC 0.906-0.942) and seven time variables did not show good reliability (ICC 0.113-0.731). Time variables (e.g. time difference between heel strike and maximal acceleration of vaginal accelerator) showed low reliability. However, relevant PFM EMG variables during running (e.g., pre-activation, minimal and maximal activity) could be identified and showed good reliability. Conclusion Further adaptations regarding measurement methods should be tested to gain better control of the kinetics and kinematics of the EMG probe and accelerometers. To our knowledge this is the first study to test the reliability of PFM activity and time variables during dynamic functional whole body movements. More knowledge of PFM activity and time variables may help to provide a deeper insight into physical strain with high force impacts and important functional reflexive contraction patterns of PFM to maintain or to restore continence.

Pelvic floor muscle electromyography during different running speeds: an exploratory and reliability study

“…All PFM EMG variables of all running speeds show clearly higher values than PFM activity during standing without any voluntary contraction, whose mean of 29.6 %EMG being similar to the findings of Luginbuehl et al [6] and Lauper et al [21]. The higher values than during standing without any voluntary contraction suggest a PFM pre-activity and reflex activity during running.…”

“…The subjects were instructed in the vaginal insertion of the surface EMG probe using ultrasound lubrication and then performed the insertion themselves. The subjects wore a loose running suit and were barefoot, as the various shock absorption systems of the subjects' individual running footwear could influence running ground reaction forces and force transmission [6].…”

“…Between the single measurements, a 15-s break was taken. The MVC testing while standing was chosen instead of the usual MVC testing in a supine position [6,14] because it seemed more functional in comparison with running. Thereafter, the subjects performed a warm-up of walking (5 km/h) for 30 s, then running at 7, 9 and 11 km/h consecutively until they reached a steady state.…”

“…To date, few studies are available investigating PFM activity during high-impact loads and hardly any of those concern functional whole-body movement situations, e.g., sports activities. Luginbuehl et al [6] found PFM electromyography (EMG) pre-activity of 72.1 %EMG [EMG normalized to maximal voluntary contraction (MVC)] at 50 ms prior to the heel strike during running at 8 km/h, which means a PFM activity of approximately 40 %EMG higher than PFM activity during standing without any voluntary contraction. They also found an immediate strong increase up to a mean maximal PFM EMG activity of 124.3 %EMG within 214.2 (±51.8) milliseconds (ms) after the heel strike, which suggests involuntary and therefore PFM reflex activity during running impact loads [6].…”

“…Luginbuehl et al [6] found PFM electromyography (EMG) pre-activity of 72.1 %EMG [EMG normalized to maximal voluntary contraction (MVC)] at 50 ms prior to the heel strike during running at 8 km/h, which means a PFM activity of approximately 40 %EMG higher than PFM activity during standing without any voluntary contraction. They also found an immediate strong increase up to a mean maximal PFM EMG activity of 124.3 %EMG within 214.2 (±51.8) milliseconds (ms) after the heel strike, which suggests involuntary and therefore PFM reflex activity during running impact loads [6]. Further studies also found PFM pre-activity and reactivity [7,8], however, those PFM activity measurements all took place in static positions of the subjects (standing or supine).…”