As a carrier for oxygen and nutrients, the blood is literally the lifeline of your organs. Heart rate reflects the efficiency with which your heart pumps this precious fluid to the rest of your body every minute. This process is so important that, whenever pumping efficiency diminishes, your brain sends signals to accelerate your heart rate. Several factors can trigger this reaction, including environmental factors, exercise, disease conditions, and emotions, according to the National Institutes of Health.
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Normal Resting Heart Rate
Beyond the age of 10, the human heart normally beats at a rate of 60 to 100 beats per minute, or bpm, at rest. It's not unusual, however, for athletes to have resting heart rates as low as 40 bpm, according to Medline Plus. Since the heart is a muscle, it can get stronger with training. A stronger heart requires less effort, or a fewer beats, to pump the same amount of blood as an untrained heart.
Environmental Factors and Heart Rate
Your body continually adjusts your heart rate in response to environmental and internal challenges. For instance, according to FitMed, heat and humidity can raise your resting heart rate beyond normal values as your body attempts to maintain adequate core temperatures. Certain drugs also can increase your heart rate, including: bronchodilators such as Isoproterenol, Ephedrine or Bronkosol; caffeine; nicotine; meth-amphetamines and cocaine.
Exercise and Heart Rate
Your heart rate can double or triple during intense exercise, says Howard University Professor of Medicine Otello Randall. In fact, immediately before a physical activity, your autonomic nervous system triggers a series of reactions in your body that start the process of gradually elevating your heart rate: this is the pre-exercise anticipatory response. Exercising muscles require more oxygen and nutrients than resting muscles to function properly. Your heart must therefore increase its pace and pump more blood during a workout.
Illness and Heart Rate
Infections and dehydration can cause your heart rate to go up, says Medline. Indeed, dehydration leads to blood volume, and therefore blood pressure, reductions. The pressure receptors in your arteries are so sensitive that even small changes can trigger a response from your brain stem. As a result, heart rate accelerates to maintain an adequate blood flow to your organs. Similar reactions occur with hemorrhage, or blood loss. Dr. Randall also remarks that heart rate elevation can be a sign of heart conditions, such as cardiomyopathy and heart failure.
Emotions and Heart Rate
The terms "pulse" and "heart rate" are often used interchangeably. As North Carolina-based physician Julian Whitaker explains, blood pressure and pulse rates change similarly during the proverbial "fight-or-flight" response to stress. Whenever your brain perceives a threat or stress, it triggers a cascade of hormonal reactions leading to an acceleration of your pulse and respiration rates. Thus, stressful situations can drive your heart rate up, particularly when associated with strong emotions such as fear or anger.
Measuring Your Heart Rate
The most common areas of pulse measurement are the radial artery in your wrist and carotid artery on either side of your Adam's apple. You can locate your pulse by firmly pressing the chosen area with two fingers, but not your thumb. Then, count the beats for a full minute. Some people count the beats for 30 or 15 seconds and multiply the result by two or four, respectively. Note also that deep breathing can skew your results.
Your heart rate is a simple, yet very informative indicator of your overall health. For instance, tachycardia, which refers to a consistently elevated resting heart rate, may be a sign of an underlying problem. Other occurrences that may warrant consulting your doctor include: bradycardia, or abnormally low resting heart rate; prolonged bounding pulses; irregular pulses; and absent pulses.