1. Heart
   1. Heart size
   2. Left ventricle undergoes most changes
   3. Internal dimensions increases in response to increase in ventricular filling ie. ↑ distensibility
   4. Wall thickness increases due to increase in strength ie. ↑ contractility
2. Heart Rate
   1. RHR decreases with training
   2. Sedentary – decrease by 1 bpm per week during initial training
   3. HR submaximal – decrease is by 20-40 bpm after 6 months of training
   4. HR maximal slightly decreases because optimum SV to maximize cardiac output
   5. HR recovery decreases with training, suitable indicator to monitor progress, but not suitable for comparison between individuals
3. Cardiac Output
   1. Slight change during rest & submaximal exercises
   2. Increases during maximal exercises because increased in SV
4. Blood Volume
   1. Endurance training causes increased in blood volume, due to increased in plasma volume which is one of the most significant effects of training
   2. Increased in rbc, but increased in plasma volume is >, therefore > fluid, hence decreased in blood viscosity, therefore increased in blood circulation
   3. Plasma volume increases because increased in SV & VO2max
5. Blood Flow
   1. Increase capillarization
   2. Increase opening of existing capillaries
   3. Increase in blood redistribution
6. Stroke Volume
   1. Endurance training causes SV to increase during rest, submaximal and maximal exercises
   2. Increased in EDV due to increased in blood plasma, also due to increased in contractility of the heart
7. Blood Pressure
   1. Resting BP decreases with endurance training in borderline cases
   2. Endurance training causes little or no effect on BP during submax & max exercises