Heart rate, also known as cardiac rhythm or heartbeat, indicates the number of heartbeats per minute. Among its many uses in medicine, heart rate is used to monitor exercise intensity and to set training goals.
You can measure heart rate by taking your pulse on different parts of the body (your wrist, neck, groin, and chest, among others). Probably the most practical way to measure your heart rate is on the wrist in the following way: 
- Place your index and middle fingers on the front side of your wrist and your thumb on the opposite side, at the same level.
- Press until you can feel your pulse.
- Count the number of heartbeats during one minute (you can also do it for 30 seconds and multiply the figure by two or for 15 seconds and multiply it by four).
- The resulting number corresponds to your heart rate.
To exercise at a moderate intensity, the established target heart rate is 60 - 85% of the maximum heart rate, which is calculated based on age, and your heart rate at rest (heart rate value in the morning, before getting up).
Athletes typically have a lower heart rate at rest than people who do not exercise. This indicates a better physical condition, since those who exercise adapt themselves more easily to the effort and also recover faster after each training session.
Remember to ask your doctor before startinga new exercise routine, or if you are going to make significant changes in your current dietary habits.
Reviewed literature:
Seidel HM, Ball JW, Dains JE, Benedict GW. Mosby's Guide to Physical Examination . 6th ed. Philadelphia, Pa: Mosby; 2007. Reviewed in July, 2008 at http://www.nlm.nih.gov/medlineplus/spanish/ency/article/003399.htm.
