Stroke volume and resting heart rate - they are both interrelated and an increase in one results in a decrease in the other. Stroke volume is simply the amount of blood that is ejected from the left ventricle at each systolic beat. The lower the heart rate - the higher the stroke volume and the more enriched blood that is pumped out to the arterial walls.
Typically the stroke volume for a untrained man at rest would be 75 ml (per pump) and 105 ml for a trained athlete at rest. Think of your heart and stroke volume as it being a musical accordion - resting and pumping with each stroke. You can tune up your heart as you can a musical instrument.
The same golden rule applies; diet, exercise, hydration, and rest will help increase your stroke volume and lower your resting heart rate.
Increase the pump - pass it on. DB