KINE 3012 Lecture Notes - Lecture 14: Ejection Fraction, Coronary Artery Disease, Diastolic Heart Failure
3 Dec 2013
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Document Summary
Instead of plotting length of muscle, we measure diastolic volume. We exist at a very low level of our maximal tension compared to skeletal muscles where they are usually at optimal. We activate more motor units to gain more tension so not all the muscles are contracting sometimes, cardiac muscles activate all the muscles during contraction. We exercise to increase strength of contraction, we get more blood into the heart, we get an increase in stroke volume, *25% increase in stroke volume* As you lengthen that muscle, you have a greater myosin actin overlap. Conclusion, if you get more blood into the heart, you"re going to increase your stroke volume. Reason we don"t live at optimal level because if we exceed, we"ll lose tension. Professional athletes can squeeze 150ml of blood, so there"s still room for improvements to reach optimal length. Another way to increase heart rate, affect the parasympathetic/sympathetic nervous system. Greater increase in intracellular calcium, reach threshold faster.
