n cardiac output is due to an increase in both heart rate and stroke volume. When the level of exercise reaches 40% to 60% of the individual's capacity, stroke volume reaches a maximum and increases cardiac output (increase is due to heart rate increase is response to sympathetic nerve stimulation of the SAN) (Brown, 2006).
             Heart rate, both at rest and during exercise, is controlled by the nervous system. The sympathetic nerves increases heart rate while you exercise as while the parasympathetic nerves slow the heart rate after you are done(Kraemer, 2012). The sympathetic nerve, carries nerve impulses from the medulla oblongata in the brain to the heart. The heart responds by increasing both the rate of contraction and the strength of the contractions (MacMillian, 2012). Exercise is one way that this pathway is activated, and can increase your heart rate to up to 180 beats per minute. This will
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