Author(s): PASTORIO, E., PAPALE, O., FESTINO, E., DI GENNARO, S., HODSON-TOLE, E., ANSDELL, P., BURNIE, L., Institution: NORTHUMBRIA UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 1842

INTRODUCTION:
In cycling, a rider’s capacity to produce high power outputs after accumulating a certain amount of high intensity work represents a key determinant of elite performance [1]. Recently, female cyclists (F) were reported to experience lesser reductions in submaximal thresholds than males (M) after heavy intensity cycling [2]. However, sex differences and hormonal influences on severe intensity performance and durability are currently unexplored. This study aimed to investigate the effect of sex and menstrual cycle (MC) on time to exhaustion (TTE) and physiological responses at 110% of critical power (CP), and the decrement (%) in peak power output (Ppeak) achieved during a 6s maximal sprint performed in fresh (Sfresh) and fatigued conditions (Sfat).
METHODS:
37 cyclists (18M, age 33±7 years, V̇O2peak 56±6 ml.kg-1.min-1, and 18F, age 32±8 years, V̇O2peak 51±3 ml.kg-1.min-1) visited the laboratory 7 times. Visits 1-4 were used to determine the power-duration relationship (i.e., CP and W’). Then in visits 5-7, participants performed the same experimental protocol, consisting of Sfresh, TTE and Sfat. During TTE, breath-by-breath gas exchange (e.g., V̇O2, V̇CO2, V̇E), heart rate (HR), near-infrared spectroscopy, and rating of perceived exertion (RPE) were recorded. Naturally menstruating females (n=10) performed the experimental protocol during the early, late follicular and mid luteal phases, confirmed by urinary ovulation testing and hormone quantification. Females taking hormonal contraceptives (n=8) and M were tested 7-10 days apart to mimic the time between phases of the MC.
RESULTS:
No sex differences were detected for both TTE (M 636±219 vs F 613±139s, p= 0.713) and Ppeak decrement (M -7±7% vs F -7±6%, p= 0.929). During TTE, V̇O2, V̇CO2, and V̇E (all % peak) increased over time (p<0.001) without sex differences, as did HR and RPE. A time × sex interaction (p<0.001) was detected for tissue oxygenation index, which decreased more in M than F.
No main effect of MC phase or group × phase interactions were observed for TTE (p≥0.935) and Ppeak decrement (p≥0.336). Despite this, the coefficient of variation (CV%) for TTE was greater in naturally menstruating females (17.3±9.5%) compared to M (10.5±7.0%) and females taking hormonal contraceptives (8.6±3.2%, p≤0.041). CV% for Ppeak decrement was not different among groups (p=0.531).

CONCLUSION:
Our results revealed that neither sex nor MC influence performance within the severe intensity domain, as well as decrement in Ppeak in fatigued state. However, the observed greater variability in TTE performance among the MC in naturally menstruating females compared to both M and females taking hormonal contraceptives suggest that there is substantial heterogeneity in changes across the MC. Thus, coaches working with naturally menstruating female cyclists are encouraged to track and adopt a personalised approach around training and MC, when needed.
REFERENCES
1. Van Erp T et al. 2021
2. Pastorio et al. 2025