Resting heart rate is a simple tool that can be really helpful in several situations. I recommend all athletes to measure their resting heart rates once in while get a picture of their normal resting heart rates. It can help you to follow your body’s reaction to training, stress and environment.
When you have a good feeling of your normal beats per minute, it’s easier for you to discover illness, dehydration or lack of recovery.
The most common way to measure resting heart rate is to put on your heart rate monitor when you wake up in the morning. Stay in bed for a few minutes and then watch your heart rate.
Should you measure resting heart rate when you sleep?
Some people actually sleep with their strap around the chest to investigate their rhytms during the night and maybe catch an even lower resting heart rate when they sleep.
Even though sleeping with the transmitter sounds more correct, measuring the whole night does not tell you much more than measuring a few minutes in the morning. For practical implications the morning routine while be just fine. Your heart rate might have been three beats lower earlier in the morning but that doesn’t matter.
Don’t make things too complicated. Measure your resting heart rate in the morning and don’t worry about your absolute lowest heart rate during the night. The morning resting heart rate works very well for practical implications. It’s not rocket science, it’s just a hint about things you probably already have a clue about.
Why is your resting heart rate higher than normal?
Illness – If you have fever, you’re heart rate accelerates with 10-15 beats for every degree your temperature goes up. When you have fever: Don’t train.
Lack of recovery – If you’ve performed a hard training session the days before, it’s very likely that your resting heart rate is 4-to 8 beats higher than normal. This is a part of the response to intensive training. It does not mean that you’ve trained too hard, but it gives you an important hint that your body need some extra recovery time before new hard training session.
Dehydration – If you’re dehydrated your total blood volume goes down and forces your heart to beat faster. Read more about central adaptations to endurance training. If you go to a hotter climate, your body will have to acclimatize to higher temperatures and humidity.
Why is your resting heart rate lower than normal?
Overtraining – This is not so common, but it can happen when you’ve been overtrained for a longer period.
Progress – This is probably a trend you will discover over months rather than over night. You will probably already have noticed that your resting heart is lower when you are in good shape. This is because of a larger stroke volume or more correctly a bigger parasympathic drive on the sinus node.
If you want to read more about the physiology behind resting heart rate, I suggest you read my post Central Adaptations to Cycling Training.