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Your resting heart rate is not a static number. It changes over time and day-to-day depending on your health, lifestyle, and environmental conditions.

These changes to your resting heart rate provide a peek into what is going on with your body. These three surprising things that alter your resting heart rate provide insight into how changes in your health affect this easily measured biometric.

Measuring Your Resting Heart Rate

The American Heart Association recommends that you check your resting heart rate first thing in the morning before you get out of bed. For best results, choose a morning when you wake up naturally since many of us are startled by the sound of the alarm. If that isn’t possible, try relaxing for a few minutes before you take your resting heart rate.

If you took your resting heart rate each morning, you would find that some mornings it is higher and others lower. This will vary depending on whether you are fighting illness, slept well, and where your hormonal cycle is that day (especially if you are female). Many of the same things that affect Heart Rate Variability (HRV) also may change your resting heart rate.

Please note, the information in this post is not a substitute for medical or professional advice. It is simply general information.

Three Surprising Things That Change Your Resting Heart Rate

1. Dehydration

Fitness enthusiasts often use heart rate monitors to track their working heart rate. Competitive and recreational runners may use heart rate training to ensure they work at the right intensity for each workout within their training program.

However, the benefits go deeper. An increased heart rate is also one of the symptoms of dehydration. This also can happen at rest especially on a hot day. WebMD lists increased heart rate as a warning sign of dehydration. According to WebMD, the increase in RHR also indicates the degree of dehydration:

“Normally, when you have been lying down and then stand up, there is a small drop in blood pressure for a few seconds. The heart rate speeds up, and blood pressure goes back to normal. However, when there is not enough fluid in the blood because of dehydration and the heart rate speeds up, not enough blood is getting to the  brain. The brain senses this condition. The heart beats faster, and if you are dehydrated, you feel dizzy and faint after standing up.” (Source Dehydration in Adults, Web MD)

Tip or Application: Stay hydrated both at rest and during exercise to maintain your normal heart rate. Be aware that excessive hydration can lead to a rare and dangerous condition sometimes known as “water intoxication.” Always practice moderation!

2. Changes in Health

Your resting heart rate (RHR) provides a barometer into your health and hormone balance. It reflects the efficiency of your cardiovascular system much like your HRV reading. Keep in mind that your genetics affect your resting heart rate so some people tend to run a little faster while others typically have a slower RHR. However, within your normal range, the following factors can alter your RHR:

  • Pregnancy – pregnancy typically increases RHR very early. Sometimes women who measure their Basal Body Temperature (BBT) while trying to conceive also take their resting pulse. Often they find both their core body temperature and their heart rate increased before a home pregnancy test confirmed the result.
  • Thyroid conditions – People with underactive, or hypothyroid, often find their RHR decreased. On the other hand, those with overactive, or hyperthyroid, find their RHR increases.
  • Other hormone changes – Both of the previous factors involve a change in hormone balance, other hormone changes may also affect RHR.
  • Weight gain or loss – Sometimes when people gain weight their RHR increases and weight loss decreases it. Of course, improvement in cardiovascular fitness also result in a lower resting heart rate (at the lower end of your normal range).

Tip or Application: Regularly monitor your RHR and HRV. If you notice changes that last longer than a few days consider whether there may be any changes to your health or hormones. If you think so, be sure to schedule an appointment with your doctor.

3. Overtraining or Stress

We previously covered how stress can lower your HRV, it also can raise your RHR. The same applies to training hard without allowing adequate recovery from your workouts. Some athletes track both their HRV and RHR to gauge their recovery. Inadequate sleep can also hinder your ability to recover from physical and mental stress. This also results in decreased HRV readings and increased RHR.

Tip or Application: Use your Biostrap to tracks trends in both your RHR and HRV measures. Consider taking active recovery days or rest if your readings indicate that you need rest.

Your biometrics offer insight into the state of your health. Devices like Biostrap make it easier to track trends in key biometrics including resting heart rate, blood oxygen saturation levels, resting heart rate, and working heart rate. It is easier than ever to monitor these metics and to use this information to live your healthiest life.

Sources and Resources

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