Author(s): NISHIKAWA, Y., NAKAMURA, M.1, UCHIZAWA, A.1,2, HOSHI, D.1, KAMEOKA, M.1, KAWABE, R.1, NOSE-OGURA, S.1, SHIRAI K.1, NAKAJIMA, K.1, Institution: JAPAN INSTITUTE OF SPORTS SCIENCES, Country: JAPAN, Abstract-ID: 881

INTRODUCTION:
Pregnancy and postpartum substantially affect athletes’ careers. In general, 22.3–59.0% experience low back pain and/or pelvic girdle pain likely due to altered spinal alignment and reduced function of abdominal muscle and pelvic floor muscle (PFM). While athletes report similar pain prevalence [1], longitudinal changes in their spinal alignment and PFM function remain scarcely investigated, despite their importance for safe return to sport. Therefore, this study exploratively investigated these parameters in elite athletes.
METHODS:
Eight elite athletes (age:30.8 ± 4.5years) participated. Seven athletes had vaginal deliveries, and one had a cesarean section; seven were primiparous and one was multiparous. Measurements were conducted at mid-pregnancy (Mid; 20–22 weeks), late pregnancy (Late; 30–32 weeks), and 1 and 3 months postpartum (1M and 3M). Spinal alignment was assessed using whole-body three-dimensional photonic scanning (Body Line Scanner C9036, Japan). Markers were placed on the spinous processes of C7, T12, and S2, and data were collected in a neutral standing posture. A C7–S2 spinal line was constructed from polygon data, and thoracic kyphosis and lumbar lordosis angles were calculated as central angles based on the Flexicurve method [2]. PFM endurance was assessed by digital palpation performed by a physical therapist and classified as possible or impossible to sustain a 10-s voluntary contraction [3]. Repeated-measures one-way ANOVA with Bonferroni post-hoc tests were used for spinal angles, with the significance level set at p < 0.05. Partial eta-squared (η²ₚ) was used to assess the magnitude of significant differences (η²ₚ ≤ 0.01 small, ≤ 0.06 medium, ≥ 0.14 large), and Cohen’s d was calculated as an effect size (d ≤ 0.2 small, ≤ 0.5 medium, ≥ 0.8 large). The proportion of participants able to sustain a 10-s PFM contraction was determined for each phase.
RESULTS:
No significant phase effect was found for lumbar lordosis (p > 0.05, η²p = 0.16) or thoracic kyphosis (p > 0.05, η²p = 0.06), and no significant post-hoc differences were found. A moderate effect size (d = 0.87) was observed for lumbar lordosis from Late (47.0 ± 10.4°) to 1M (55.8 ± 10.7°), whereas thoracic kyphosis showed only small effect sizes (d = 0.06-0.41). PFM endurance sustainment rates were 37.5% (Mid), 75.0% (Late), 37.5% (1M), and 62.5% (3M).
CONCLUSION:
Although no statistically significant phase effects were detected, moderate changes in lumbar lordosis were observed from Late to 1M, whereas PFM endurance appeared to be temporarily reduced at 1M before recovering. These findings may help guide decisions regarding training intensity during the early postpartum period.
References
1. Bø et al., Scand J Med Sci Sports, 2007.
2. Grindle et al., JOR Spine, 2020.
3. Starzec-Proserpio et al., Int. J. Environ. Res. Public Health, 2022.