Author(s): KAMEOKA, M.1, NAKAMURA, M.1, SOEJIMA, Y.1, YOKOTA, R.1, NISHIKAWA, Y.1, UCHIZAWA, A.1,2, HOSHI, D.1, KAWABE, R.1, NOSE-OGURA, S.1, SHIRAI, K.1, NAKAJIMA, K.1, Institution: JAPAN HIGH PERFORMANCE SPORT CENTER, Country: JAPAN, Abstract-ID: 907

INTRODUCTION:
The number of elite female athletes returning to competition after pregnancy and childbirth has been steadily increasing [1]. However, quantitative evidence describing postpartum strength training composition and the process of strength recovery remains limited [2]. Power-oriented resistance training (PRT) is a key component of athletic performance, and the timing of its introduction is particularly important during the return-to-sport process [3]. The purpose of this study was to quantitatively evaluate longitudinal changes in training composition and strength recovery in elite athletes who returned to competition postpartum, and to examine the timing of PRT　introduction to inform the development of safe and effective return-to-sport protocols.
METHODS:
Five elite athletes who returned to competition after childbirth (age: 30.8 ± 5.2 years) were included. Training logs from 1 to 12 months postpartum were analyzed. Exercises were classified into eight categories: collective (CE), bodyweight (BW), core (CORE), upper-body resistance (UBR), lower-body resistance (LBR), plyometrics (PLY), medicine ball training (MBT), and quick lifts (QL). Monthly average sets per category were normalized per training day to characterize session-based training composition. PRT (PLY, MBT, QL) were introduced after confirmation by a physiotherapist of pelvic floor muscle function, trunk stability, and absence of pain or urinary incontinence. Training programs were designed by S&C coaches. Squat one-repetition maximum normalized to body mass (1RM/BM) was assessed at 3, 6, and 12 months postpartum. Longitudinal changes were analyzed using linear mixed-effects models with Bonferroni-adjusted post hoc tests (α = 0.05).
RESULTS:
In the early postpartum period (1-3 months), training was primarily composed of BW and CE exercises. From 4 months postpartum onward, the number of sets for resistance training exercises (UBR and LBR) increased. PRT was introduced in a staged manner: PLY at 4 months, MBT at 7 months, and QL at 8 months. Relative squat strength (1RM/BM) increased significantly from 3 to 12 months (p = 0.001), with a 24.6 ± 16.5% increase from 3 to 6 months (p = 0.017) and a further 17.1 ± 4.2% increase from 6 to 12 months (p = 0.027).
CONCLUSION:
PRT was introduced at 4 (PLY), 7 (MBT), and 8 months (QL) postpartum, providing potential reference points for training planning. Improvements in 1RM/BM by 6 months suggest concurrent functional recovery, supporting earlier and gradual introduction of PRT when pelvic floor function and trunk stability are restored.

References
1. Canadian Society for Exercise Physiology, Appl Physiol Nutr Metab, 2025.
2. Rotheram et al., Br J Sports Med, 2022.
3. Deering et al., Int J Sports Phys Ther, 2019.