tachycardia

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tachycardia An increase in heart rate. The heart rate is controlled by the opposing actions of the sympathetic nervous system, which accelerates the heartbeat; and the parasympathetic nervous system, which slows it down. The heart rate is normally approximately 70 beats per minute. During exercise there is an increase in sympathetic activity and tachycardia occurs: the heart rate increases to up to 110 beats per minute. Immediately after exercise, at rest, the heart rate decreases to around 60 beats per minute (bradycardia), due to an increase in parasympathetic activity.

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