The main goal of this study was to show how V̇O2max affect left ventricular function when an athlete does moderate to maximum treadmill which can help to evaluate cardiovascular fitness. As an athlete start doing treadmill, depending on the need of oxygen to tissues, cardiac output, stroke volume, left ventricular ejection fraction and myocardial activity along with increased Vo2max, Data collection was done at D Y Patil Hospital, Navi Mumbai after taking permission from medical ethic committee. After asking to do treadmill, systolic time interval were estimated for finding Vo2max and left ventricular ejection fraction, taking into consideration duration. For proper results, athletes were asked to do treadmill for 2 weeks As an athlete perform treadmill, V̇O2max was found to be increased with a gradual increase in left ventricular ejection fraction was somewhat increased ( P<0.005) Thus in athletes, V̇O2max was to be much more correlated with left ventricular ejection fraction (P<0.005).