Left Ventricular Response to Submaximal Exercise in Endurance-Trained Athletes and Sedentary Adults John R. Schairer, DO, Paul D. Stein, MD, Steven Keteyian, PhD, Frank Fedel, Jonathan Ehrman, Mostjn Alam, Ml& Jerald WYHenry, and Tracy Shaw This investigatkn examiner the hypothesis that athktes increase stroke volume with submaximal exercise through an augmentation of left ventrkubr (LV) end-diastolk volume and a reduction of LV end-systolk volume, whereas sedentary adults only imrease stroke volume modestly, because LV ~d-diastolic volume does not increase. Upright Mcycle exercise was performed by 17 epdurancetrained male athletes and 15 sedentary men. Mmode echocardiograms were obtained during submaximal exercise at predetermined heart rates. Athletes, at a heart rate of 130 beats/min, increased their stroke votume 67% from 72 f 16 ml to 120 f 26 ml (p