Menstrual Disruption with Exercise Is Not Linked to an Energy Availability Threshold.

Introduction: Chronic reductions in energy availability (EA) suppress reproductive function. A particular calculation of EA quantifies the dietary energy remaining after exercise for all physiological functions. Reductions in luteinizing hormone pulse frequency have been demonstrated when EA using this calculation is <30 kcal·kg·fat-free mass (ffm)·d.

Magnitude of daily energy deficit predicts frequency but not severity of menstrual disturbances associated with exercise and caloric restriction.

We assessed the impact of energy deficiency on menstrual function using controlled feeding and supervised exercise over four menstrual cycles (1 baseline and 3 intervention cycles) in untrained, eumenorrheic women aged 18-30 yr. Subjects were randomized to either an exercising control (EXCON) or one of three exercising energy deficit (ED) groups, i.e.