Influence of High-Impact Physical Activity on Pelvic Floor and Lumbar Muscle Mechanical Properties in Asymptomatic Nulliparous Women.

Introduction and hypothesis: High-impact physical activity is a known risk factor for the development of pelvic floor disorders (PFDs) in women, affecting the pelvic floor muscles (PFMs). However, there is insufficient information to determine whether alterations in PFMs, or even in the lumbar muscles, can be detected before the onset of symptoms. The aim of the study was to identify whether high-impact physical activity influences the muscle mechanical properties (MMPs) of the lumbopelvic region in continent nulliparous women.

Methods: An observational cross-sectional study with a nonprobabilistic sampling of consecutive cases was designed. Fifty women who had practiced high-impact physical activity at least three times per week for more than 2 years were included in the high-impact group, and 50 women who did not practice high-impact activity were included in the control group. Data collection for both groups included sociodemographic data and MMPs (frequency, characterizing muscle tone; stiffness; logarithmic decrement, characterizing the inverse of the elasticity; relaxation time of stress; creep, characterizing fluidity) of PFMs and lumbar muscles, externally assessed using a hand-held tonometer device. Between-group comparison of the MMPs were calculated, together with intragroup correlations between the outcomes.

Results: The MMPs of PFMs showed statistically significant lower tone (0.76 Hz, 95% CI 0.04, 1.48) and stiffness (23.76 N/m, 95% CI 1.10, 46.42) and were more viscoelastic (relaxation: -1.04 ms, 95% CI -1.98, -0.11; creep: -0.04 De, 95% CI -0.07, -0.02) in women who practiced high-impact physical activity. No lumbar MMPs showed statistically significant between-group differences.

Conclusions: High-impact physical activity alters the MMPs of PFMs in nulliparous women, although not lumbar spinal MMPs, even before the appearance of signs.