Textbook Notes

The decrease in ESV is facilitated by the decrease in peripheral resistance that occurs with training. Increased contractility resulting from an increase in left ventricular thickness and greater diastolic filling (Frank-Starling mechanism), coupled with the reduction in systemic peripheral resistance, increases the ejection fraction [equal to (EDV − ESV) / EDV] in the trained heart. More blood enters the left ventricle, and a greater percentage of what enters is forced out with each contraction, resulting in an increase in stroke volume.

-Following endurance training, stroke volume (SV) is increased at rest and during submaximal and maximal exercise.

-A major factor leading to the SV increase is an increased end-diastolic volume (EDV) caused by an increase in plasma volume and a greater diastolic filling time secondary to a lower heart rate.

-Another contributing factor to increased SV is an increased left ventricular force of contraction. This is caused by hypertrophy of the cardiac muscle and increased ventricular stretch resulting from an increase in diastolic filling (increased preload), leading to greater elastic recoil (Frank-Starling mechanism).

-Reduced systemic vascular resistance (decreased afterload) also contributes to the increased volume of blood pumped from the left ventricle with each beat.

- While stroke volume increases with training, heart rate generally decreases at rest and during exercise at a given absolute intensity.

-Cardiac output can be influences by training, higher for trained individuals vs untrained individuals.