Your heart rate is your personal workout metric
Heart rate is a useful tool for understanding your sports’ performance When you train with heart rate, you'll be able to monitor and control the intensity of your workouts.
While your heart rate gives you an accurate indication of your effort, it's good to remember that there are many factors that influence it. These factors include for example:
Athletes with an extensive background in aerobic training will have more efficient heart muscles than someone with less aerobic training. The capacity of the athletes’ left ventricles will be greater than the non-athletes and their ventricular muscles will be much stronger, leading to an increased stroke volume. This increased stroke volume can be observed by a lower resting heart rate, as well as a lower heart rate during training.
As temperature increases so does the need to cool down the body. Blood flow will be directed closer to the surface of the skin to reduce temperature. This accelerated circulation requires the heart to beat faster, which means that heart rate will increase. When the surrounding air cools down, circulation in peripheral parts of the body decreases, so the heart doesn’t have to work as hard. This causes your heart rate to decrease.
When dehydrated, the amount of plasma in the blood decreases and the heart is forced to pump faster than normal. This is to provide enough oxygen and nutrients to the muscles in the peripheral parts of the body, as well as to maintain an adequate body temperature. That is why your heart rate tends to go up when you're dehydrated.
Measuring your heart rate with Polar
Polar offers two ways to measure your heart rate. One is to use a heart rate monitor with a chest strap, that measures the heart's ECG. In this case, measuring heart rate means measuring the electrical activity of the heart.
The other way to measure heart rate is to optically measure the pulse on the arteries e.g. with a wrist-based heart rate monitor. In this instance, heart rate is measured by pulse which is caused by the heart beating, i.e. heart rate.