Overview

• UCL tracked 54 naturally menstruating women aged 18–40 across four verified cycle phases using sport-like tests of reaction time, attention and timing.
• Performance peaked on the day ovulation was detected, with average simple reaction times about 30 milliseconds faster than during the mid‑luteal phase and with fewer errors.
• Mid‑luteal testing showed slower processing without reduced accuracy, while the late follicular phase produced more mistakes.
• Physical inactivity had the largest influence, with inactive participants averaging roughly 70 milliseconds slower reactions and about three times more impulsive errors across all phases.
• Menstruation symptoms reported by participants did not align with objective scores; authors note implications for women’s sport, including larger swings in elite athletes, and the findings were published in Sports Medicine–Open.