Response of exercise-onset vasodilator kinetics to L-citrulline supplementation during different phases of the menstrual cycle

<b>Purpose </b>To determine whether L-citrulline (CIT) supplementation during the follicular and luteal phases of the menstrual cycle would present differential effects on vasodilator kinetics in dynamically contracting muscle.<br><b>Methods </b>Twenty-four healthy young women not on oral contraceptives were studied during the follicular (n=13) and luteal phases (n=11). Supplementation with CIT (6g/day) or placebo occurred 7-days prior to the testing day in a crossover design across two menstrual cycles. Forearm vascular conductance (FVC) was calculated from blood flow and mean arterial pressure measured continuously during handgrip exercise performed at 10% maximal grip strength. FVC was calculated for each duty cycle (contract:relax, 1:2s) and expressed as a change from baseline (DFVC) before being fit with a monoexponential model. Amplitude of the DFVC response and the number of duty cycles for DFVC to reach 63% of steady-state amplitude (tDFVC) were derived from the model.<