Jam with Confidence: Rock Your Certified Rhythm Analysis Technician Exam 2026!

A normal cause of sinus tachycardia is exercise. During physical activity, the heart rate increases to supply more oxygen-rich blood to the muscles. This is a physiological response to meet the increased metabolic demands of the body during exercise. The autonomic nervous system plays a key role in regulating heart rate, with the sympathetic nervous system stimulating an increase in heart rate to enhance cardiac output.

In contrast, sleeping typically results in a decreased heart rate as the body enters a restful state, and myocardial infarction can lead to abnormal heart rhythms, rather than a normal increase in heart rate. Hypertension, while it may have various effects on the heart, is not a direct and normal cause of sinus tachycardia; rather, it is a chronic condition that can lead to other complications regarding heart function. Therefore, exercise is the clear and appropriate answer as a normal cause of sinus tachycardia.