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From WikiMD's Wellness Encyclopedia

H.R. (Heart Rate)

Heart Rate (H.R.) is a critical physiological parameter that measures the number of times the heart beats per minute (bpm). It is an essential indicator of cardiovascular health and overall fitness. Understanding heart rate is crucial for medical professionals, athletes, and individuals monitoring their health.

Physiology of Heart Rate[edit | edit source]

The heart rate is controlled by the autonomic nervous system, which includes the sympathetic and parasympathetic nervous systems. The sinoatrial node (SA node), located in the right atrium of the heart, acts as the natural pacemaker, initiating electrical impulses that cause the heart to contract.

Factors Affecting Heart Rate[edit | edit source]

Several factors can influence heart rate, including:

  • Physical Activity: During exercise, the heart rate increases to supply more oxygen-rich blood to the muscles.
  • Emotional State: Stress, anxiety, and excitement can elevate heart rate due to the release of adrenaline.
  • Medications: Certain drugs, such as beta-blockers, can decrease heart rate, while others, like stimulants, can increase it.
  • Temperature: High temperatures can cause an increase in heart rate as the body works to cool itself.
  • Body Position: Heart rate can vary with changes in posture, such as moving from lying down to standing.

Measurement of Heart Rate[edit | edit source]

Heart rate can be measured manually or with electronic devices. The most common sites for manual measurement are the radial artery at the wrist and the carotid artery in the neck. Electronic devices, such as electrocardiograms (ECGs) and heart rate monitors, provide more precise measurements.

Normal Heart Rate Ranges[edit | edit source]

The normal resting heart rate for adults ranges from 60 to 100 bpm. However, athletes may have a resting heart rate as low as 40 bpm. Factors such as age, fitness level, and overall health can influence these values.

Clinical Significance of Heart Rate[edit | edit source]

Abnormal heart rates can indicate various medical conditions:

  • Tachycardia: A heart rate above 100 bpm at rest, which may be caused by fever, anemia, or hyperthyroidism.
  • Bradycardia: A heart rate below 60 bpm at rest, which can occur in athletes or be due to heart block or hypothyroidism.
  • Arrhythmias: Irregular heartbeats that can lead to complications such as stroke or heart failure.

Heart Rate in Exercise and Fitness[edit | edit source]

Monitoring heart rate during exercise helps individuals optimize their workouts and ensure they are exercising within their target heart rate zone. This zone is typically 50-85% of an individual's maximum heart rate, which can be estimated by subtracting their age from 220.

Also see[edit | edit source]


Cardiovascular disease A-Z

Most common cardiac diseases

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Contributors: Prab R. Tumpati, MD