If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
The heart rate is the number of times per minute the heart beats. A normal resting heart rate for an adult is 60–100 beats per minute. The heart rate changes throughout the day, depending on a person’s level of activity. In general, the heart rate keeps up with the body’s demands. If the body is doing something that requires more oxygen, the heart rate speeds up. If the body is at rest, the heart rate slows down. The speed is determined by nerve signals and hormones. A heart rate that is too slow is called bradycardia. Bradycardia can be caused by many things, including heart block, Lyme disease, and certain medications. It can also be normal for certain types of athletes to have a low resting heart rate. A heart rate that is too fast is called tachycardia. This can also be caused by many things, including problems with the electrical signals in the heart, electrolyte imbalances, dehydration, or certain medications. Both the heart rate and the heart rhythm can be controlled with medications. In some cases, a slow heart rate may require a pacemaker.
What we mean by normal
In medicine, using the term “normal” can sometimes be off-putting. Saying something is “normal” implies that everything else is “abnormal.” Additionally, saying something is “normal” may not be accurate, since something that is “normal” for you may not be “normal” for somebody else. Therefore, instead of saying certain values are “normal,” alternative terminology may be to say that these values are “healthy” or “within the reference range.”
Additionally, some values have well-defined cutoffs, while others do not. For example, when looking at hemoglobin A1c levels, a value of 6.5 or greater is always diagnostic of diabetes. On the other hand, when looking at testosterone levels, some use cutoffs of 270–1,070 ng/dL while others use cutoffs of 300–1,000 ng/dL.
The information above represents values that are commonly used as cutoffs. However, depending on the specific source you’re looking at or the laboratory you go to, their values may be a little different.
Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine and is Ro's Chief Clinical Officer.