What Causes High and Low Heart Rates?

May 7th 2016

Fluctuating heart rates do not always indicate a heart problem. Many people experience highs and lows based on activity and physical and mental health status. Individuals with consistent higher heart rates should consult with a physician to determine if illness or heart problems could be causing the elevated or lowered rates.

Body Size

Individuals who are overweight or obese may experience a higher heart rate that edges toward 100 when resting. When sitting, standing or resting, the pulse typically maintains a consistent number, but when changing positions, the pulse may increase for a few minutes.


Anxiety and stress can cause the heart rate to increase, especially during times when people feel anxious or extraordinarily happy or sad. Individuals who are able to calm themselves down and enter a state of relaxation typically notice that the heart rate lowers.


Certain medications can cause the heart rate to lower, ultimately slowing down the pulse. Beta blockers, especially, work to block the adrenaline in the body that slows the heart rate. A lower heart rate may also indicate incorrect dosages of medications. For example, individuals taking too much thyroid medication may notice an increased heart rate.

Air Temperature

People who are exposed to humidity and high air temperatures may experience a higher heart rate, commonly five to 10 more beats per minute. Heart rates typically lower once the body has adjusted to the temperature or is exposed to cooler air.

Physical Activity

Any type of activity or exercise causes the heart rate to slightly increase. Moderate exercises such as walking cause the heart rate to jump within the first minute of movement and then slowly regulate itself. Individuals engaged in intense and strenuous exercise often maintain a higher heart rate throughout the duration of the activity. Heart rates typically lower once the body recovers from the activity. Increased heart rates during exercise indicate that the blood is pumping faster. It is important to determine target heart rates with a medical professional prior to beginning strenuous activity. Individuals should also monitor their heart rate during exercise.


Heart rates indicate the number of times the heart beats per minutes. Normal heart rates will vary based on an individual's overall health, age and activity level. Most people experience a resting heart rate of 60 to 100 beats per minute, according to the American Heart Association. Heart rates, though, will dip into lower ranges and increase above 100 when certain factors are present. Knowing the cause of high and low heart rates helps people to monitor their overall heart health.

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