To satisfy the increased demands of your muscles during exercise, the heart will contract in a faster, more powerful manner, increasing pulse rate and blood pressure. During the rest period, your heart rate and blood pressure are expected to return to baseline within a reasonable time frame. A 2005 study in the, "Journal of Sports Science and Medicine" explains that heart rate recovery after exercise depends on many factors such as intensity of exercise, your individual cardiorespiratory fitness and response of the cardiac autonomic nervous system.
Generally, your heart rate is expected to decline 13 beats or more per minute following exercise. Many avid exercisers know approximately how long it takes for their pulse to return to normal after a workout. If your heart rate remains elevated for a considerable time period following exercise, there are a number of factors that could explain the cause.
Dehydration
During exercise, especially cardiovascular activity, some degree of perspiration is likely. It is possible to experience a continued, elevated heart post-exercise if you do not remain adequately hydrated with water or an electrolyte-infused sports drink. Dehydration can manifest in the form of rapid heart rate, dizziness and low blood pressure. Mild-to-moderate dehydration can usually be resolved by drinking fluids, while more severe cases may require medical attention and intravenous fluids.
Heart Rhythm Disturbances
Many irregular heart rhythms, or arrhythmias, are characterized by elevated heart rates. For example, inappropriate sinus tachycardia can cause an increased resting heart rate and unexplained heart rate accelerations. These symptoms tend to be noted by someone who is most aware of his heart rate, as in during a rest period following exercise. Sometimes, arrhythmias also cause symptoms such as chest pain and shortness of breath. Arrhythmias are diagnosed by a physician, using diagnostic procedures such as exercise stress testing and electrocardiograms.
Heat Stroke
Heat stroke as the cause of an elevated, post-exercise heart rate will be largely dependent on temperature changes. The University of Maryland Medical Center explains that with extreme heat, high humidity or vigorous activity in the hot sun, the body's cooling system may begin to fail, allowing your internal heat to build up to dangerous levels. With heat stroke, you may experience rapid heart rate, confusion, disorientation or even loss of consciousness. While hospitalization is often necessary to treat the condition, immediate first aid measures such as applying ice packs to the armpits and groin, are crucial.
Considerations
If your heart rate is notably elevated following exercise and after a long rest period, you may experience other symptoms like heart palpitations or shortness of breath. If this condition causes notable symptoms or is a change from your baseline state, it is advised to consult your physician in order to be properly evaluated. Controlling high, post-exercise heart rate may be as simple as adequate hydration to as complex as a cardiac procedure such as an ablation.
References
- "Journal of Sports Science and Medicine"; Heart Rate Recovery After Exercise and Neural Regulation of Heart Rate Variability in 30-40 Year Old Marathon Runners; Na Du, et al.; March 2005
- "The New England Journal of Medicine"; Heart-Rate Recovery Immediately After Exercise as a Predictor of Mortality; Christopher R. Cole, et al.; October 1999
- "Nursing"; Identifying inappropriate sinus tachycardia; Diane M. Bosen; July 2001
- University of Maryland Medical Center; Dehydration and Heat Stroke
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