Minimal influence of the menstrual cycle or hormonal contraceptives on performance in female rugby league athletes.

Abstract

We examined performance across one menstrual cycle (MC) and 3weeks of hormonal contraceptives (HC) use to identify whether known fluctuations in estrogen and progesterone/progestin are associated with functional performance changes. National Rugby League Indigenous Women's Academy athletes [n=11 naturally menstruating (NM), n=13 using HC] completed performance tests [countermovement jump (CMJ), squat jump (SJ), isometric mid-thigh pull, 20m sprint, power pass and Stroop test] during three phases of a MC or three weeks of HC usage, confirmed through ovulation tests alongside serum estrogen and progesterone concentrations. MC phase or HC use did not influence jump height, peak force, sprint time, distance thrown or Stroop effect. However, there were small variations in kinetic and kinematic CMJ/SJ outputs. NM athletes produced greater mean concentric power in MC phase four than one [+0.41W·kg-1 (+16.8%), p=0.021] during the CMJ, alongside greater impulse at 50ms at phase one than four [+1.7N·s (+4.7%), p=0.031] during the SJ, without differences between tests for HC users. Among NM athletes, estradiol negatively correlated with mean velocity and power (r=-0.44 to -0.50, p<0.047), progesterone positively correlated with contraction time (r=0.45, p=0.045), and both negatively correlated with the rate of force development and impulse (r=-0.45 to -0.64, p<0.043) during the SJ. During the CMJ, estradiol positively correlated to 200ms impulse (r=0.45, p=0.049) and progesterone to mean power (r=0.51, p=0.021). Evidence of changes in testing performance across a MC, or during active HC use, is insufficient to justify "phase-based testing"; however, kinetic or kinematic outputs may be altered in NM athletes.