Author(s): UCHIZAWA, A., NAKAMURA, M.1, KAMEOKA, M.1, NISHIKAWA, Y.1, HOSHI, D.1, NOSE-OGURA, S.1, SHIRAI, K.1, NAKAJIMA, K.1, Institution: JAPAN INSTITUTE OF SPORTS SCIENCES, Country: JAPAN, Abstract-ID: 1820

INTRODUCTION:
Continuing training during pregnancy may support postpartum return to competition in elite athletes. However, limited evidence supporting the safe continuation of training underscores the need for careful monitoring. Cervical length of the uterus is a well-established obstetric marker of preterm labor risk, and cervical shortening can necessitate training interruption. Cervical length assessment requires a transvaginal ultrasound, limiting its feasibility for routine monitoring. Bioelectrical impedance analysis (BIA) is a safe, non-invasive method for assessing body composition. BIA-derived indices, such as phase angle (PhA), reflect cellular integrity and physiological status and are sensitive to functional change, and have been applied during pregnancy to assess physiological change. Because cervical remodeling during pregnancy is influenced by systemic physiological and tissue changes, BIA-derived indices may capture biological processes relevant to cervical dynamics. Thus, BIA-derived markers may provide
METHODS:
This exploratory case study analyzed two pregnant elite athletes at the Japan Institute of Sports Sciences. One athlete discontinued training due to cervical shortening (A; 28 assessments from 13-32 weeks), whereas the other continued training without complications (B; 17 assessments from 5-34 weeks). Before each training session, medical screening included measuring cervical length by transvaginal ultrasound. Training was discontinued if cervical length was <30mm or uterine symptoms were present. Resistance (R) and reactance (Xc) were measured by BIA prior to training. Associations between cervical length and BIA parameters were examined using correlation analyses. Partial correlations were applied when cervical length was associated with gestational age and body mass; otherwise, simple correlations were applied.
RESULTS:
Athlete A discontinued training or reduced training volume and intensity on four occasions. In athlete A, cervical length was inversely associated with upper-limb PhA (r = −0.48, p = 0.034). In athlete B, cervical length showed inverse associations with multiple upper-limb BIA parameters (PhA: r = −0.61, p = 0.037; R: r = −0.71, p = 0.010; Xc: r = −0.68, p = 0.016). There were no associations in other body segments in either athlete.
CONCLUSION:
Our findings suggest that upper-limb BIA-derived indices may more accurately reflect physiological changes relevant to cervical dynamics, likely due to their relative stability against edema. Upper-limb BIA-derived indices may provide complementary, non-invasive information related to cervical changes during pregnancy. These markers may support monitoring strategies for the safe continuation of training in pregnant elite athletes.