Author(s): CHUNG, Y.W.1, LIN, Z.H.2, CHANG, J.T.1, HUANG, K.H.1, LIN, J.H.3, HSU, W.C.1, Institution: NATIONAL TAIWAN UNIVERSITY OF SCIENCE AND TECHNOLOGY , Country: TAIWAN, Abstract-ID: 2518

INTRODUCTION:
Understanding menstrual phase–related variations in neuromuscular performance is essential for optimizing training and performance monitoring in female triathletes. Hormonal fluctuations across the menstrual cycle may influence explosive force production more than maximal strength; however, evidence in endurance-trained women remains limited. This study examined differences in lower-limb neuromuscular performance between the follicular phase (FP) and luteal phase (LP), and subsequently explored phase-specific associations between body composition and strength-related variables.
METHODS:
Seventeen female triathletes underwent isokinetic knee extension and flexion testing using a Biodex dynamometer and body composition assessment via bioelectrical impedance analysis (BIA) during both FP and LP. Outcome variables included peak torque, average torque, rate of force development (RFD), RFD within the 0–50 ms interval, and hamstring-to-quadriceps (H/Q) ratio. Paired comparisons were used to examine phase differences, followed by Pearson correlation analyses conducted separately within each phase.
RESULTS:
Results showed that RFD was significantly greater during the follicular phase compared with the luteal phase (p < 0.05), whereas no significant differences were observed in peak torque, average torque, or H/Q ratio. Phase-specific correlation analyses revealed that associations between body composition and maximal strength measures were generally moderate but did not consistently predict explosive performance indices across phases.
CONCLUSION:
These findings suggest that menstrual phase may influence rapid force production rather than maximal isokinetic strength in female triathletes. The greater RFD observed in the follicular phase indicates potential phase-dependent modulation of neuromuscular activation. These results highlight the importance of considering menstrual phase when interpreting explosive performance metrics and when evaluating the physiological relevance of BIA-derived measurements in female endurance athletes.