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What Affects Resting Heart Rate?

Progress is a huge motivator – and paying attention to your resting heart rate is an excellent way to gauge how your aerobic fitness is improving. Read on to understand what affects resting heart rate and why it matters.

Measuring your resting heart rate regularly allows you to see long-term progress and daily fluctuations that can tell you whether you’re fit for training, overtrained or stressed.

A normal value for an adult is between 60 and 80 beats per minute. If you’re fit, your resting heart rate can be significantly lower than that. To find out what’s your lowest resting heart rate, the best moment to measure it is in the morning after a rest day. After strenuous exercise, your sympathetic nervous system will be active and your resting heart rate higher. There are also several factors that affect your heart rate while exercising.

If you notice changes in your resting heart rate, read through this list and see if there’s something that could explain the said changes.


Resting heart rate usually increases with age. This is mainly due to the decline of physical fitness.

State of training

Your sympathetic nervous system is more active during recovery than when you’re well recovered. Also the hormonal state (adrenaline) and the recovery processes of your body keep your heart rate up for several hours after training.

If your resting heart rate is elevated, your body could be in a state of overtraining due to too much training and too little recovery.

Resting heart rate and fitness

Training background

When you do aerobic training long enough, your heart will become more efficient. The capacity of your left ventricle will increase and your ventricular muscles will become stronger which leads to an increased stroke volume. That is, your heart will pump more blood per beat than before.

When you do aerobic training long enough, your heart will become more efficient.

This increased stroke volume can be observed as a lower resting heart rate as well as a lower training heart rate. Perfectly logical, right? To pump the same amount of blood, your heart needs fewer beats because the volume per beat has increased.

Note that extensive strength training that aims to increase muscle mass elevates the resting heart rate – especially if the aerobic fitness deteriorates simultaneously.


As the temperature rises, so does the need to cool the body down.

In higher temperatures, blood flow is directed closer to the surface of the skin so that blood can be cooled down. Your heart beats faster to accelerate your blood circulation and so regulate your body temperature.

Conversely, when you’re in a cooler environment, the blood circulation in peripheral parts of the body decreases. Your heart has less work to do and your resting heart rate will decrease.

Heat affects your resting heart rate


When you’re dehydrated, the amount of plasma in the blood decreases. Because there’s less blood in your body, your heart has to pump faster than normally to maintain an adequate body temperature and to provide enough oxygen and nutrients to muscles in peripheral parts of the body.

This is why your resting heart rate tends to go up when you’re dehydrated.


Mental or physical stress increases the activity of the autonomic nervous system.

When under stress, the central nervous system orders the heart, as well as your brain and large muscles, to prepare for a fight-or-flight situation. This leads to an increase in your resting heart rate.

Stress increases your heart rate at rest

State of mind

Different emotions affect the autonomic nervous systems through hormonal activity.

When you’re very calm, the activity of the autonomic nervous system lowers your heart rate. When you’re very excited, your heart rate goes up.

So by controlling your emotions you can also control your resting heart rate indirectly.


Your genome is one of the most important factors affecting the resting heart rate. The effect of genes on the resting heart rate can be seen as a difference of more than 20 beats per minute in two persons of the same age and level of fitness.

But my mom/brother/friend/neighbor…

You shouldn’t compare your resting heart rate with someone else’s. You’re unique and beautiful and that’s how it should be. While your neighbor’s resting heart rate might be lower than yours, it might be for a dozen different reasons.

Instead of comparing yourself to others, you’re better off monitoring how your resting heart rate is changing over time. When your resting heart rate decreases as a result of training, it’s a sign that your aerobic fitness has improved.

Take that, neighbor.

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Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.

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