Understanding Heart Rates
Why heart rate?
Courtesy of Harald Zumpt- POLAR
The use of heart rate and heart rate monitors in exercise was introduced in the early 1980’s. Steadily the use of these devices has grown over the years and considered by most to be a standard piece of equipment especially in endurance sports. Heart rate monitors are now also being used on horses and no longer only on humans.
With the introduction of commercially available power output sensors, the use of heart rate, especially in cycling, has recently been questioned.
Let’s take step back and have look at what actually affects the number on your wrist and what it really means.
During physical activity the exercising muscles require two things, energy and oxygen. The amount of energy and oxygen that are being demanded largely depends on the intensity of the activity. Simply put the brain will register the demand and send a message to heart to deliver. Your heart rate is therefore not a measure of your hearts ability to do work but more a measure of what is happening in other parts of your body.
Your heart rate will only go as high as it needs to. For those of you that have used a heart rate monitor will probably have experienced some days were you are just unable to get your heart rate up. This may be a sign of muscle fatigue. A fatigued muscle is unable to demand the required energy and oxygen and will therefore the heart rate will not respond.
During exercise, heart rate is a reflection of exercise stress and simply put what does it “cost” the body to do a certain activity. Factors such as speed, pace or power output are merely the result, which may be affected by numerous factors beyond our direct control. At the end of the day, no matter what the result may be, we still need to have some idea what it will “cost” us.
Exercise stress, reflected by your heart rate, can therefore be seen as a function of various factors such as:
- Exercise Intensity
- And probably numerous other factors we are not totally aware of yet.
Being ill is one form of stress on your body and would be reflected in an increase in your heart rate. An increase of 10-15 beats per minute in your resting heart rate may be an indication that things are about to go wrong.
It is never advisable to training during an illness. Wait till your resting heart rate has returned to normal and you are no longer on medication such as anti-biotics. Once things return to normal, it is a good idea to focus on low intensity training (below 70% of maximum intensity) for a further 14 days.
Measuring your heart rate is still the most convenient and accurate way of listening to your body.