FITNESS
Using a heart rate monitor: the basics
Dr Bridget Farham
Posted Tue, 30 May 2000

We all know that elite athletes train with heart rate monitors. But are they really any use for us recreational "athletes"? Since accurately measuring your heart rate during exercise allows you to tailor your training in specific ways, they almost certainly are worthwhile, particularly if you are a fairly dedicated recreational athlete.

Heart rate monitors provide biofeedback information. This is the key to regulating the intensity and quality of your workout. Scales of perceived exertion will give you some idea of how you are doing, but are very subjective. If you are of the "no pain, no gain" frame of mind, then you are likely to push yourself too hard most of the time, which will result in less than useful training. A heart rate monitor allows you to work within sensible limits, determined by the type of training you are aiming for, in a controlled way.

Heart rate monitors

You've spent the money and bought your monitor, possibly paying quite a lot for it, although the cheapest models come at around R300 at present.

The first thing to do is to sit down and read the manual from cover to cover! You won't learn how to use it properly by trial and error, particularly the more expensive models which have a number of different functions.

The chest band contains the sensors which monitor your heart rate and then transmit this value to the wrist monitor. The contacts on the chest band work best if slightly damp — fine once you have worked up a sweat, but sometimes a problem at the start of a work out. Use saliva to moisten the sensor areas and you will get better contact and a good reading immediately. There are also gels available from most sports shops which serve the same function.

The wrist monitor should start to record your heart rate as soon as the chest band is in place, although it sometimes takes a few seconds to do so. Hold the wrist monitor up to the chest band to speed up this process.

If you are exercising in a crowded spinning class you may find that you get interference from heart rate monitors worn by those next to you. Speak to the person next to you and both try and optimise your distance and relative position to prevent this.

Your resting heart rate

Your resting heart rate is a useful value to know since the difference between it and your maximum heart rate, the heart rate reserve, determines the range of different training intensities at which you can work. The greater your heart rate reserve the greater the range of intensities at which you can train. In general the lower your resting heart rate (in a healthy person on no medication) the fitter you are.

To measure your resting heart rate, record your heart rate immediately on waking in the morning, before getting up and moving around. It is easiest to sleep with the chest band and monitor on and then read the monitor immediately you wake up. Do this on a morning when you do not need the alarm clock to wake you up, since that will usually raise your heart rate!

Another way of doing this is to put the apparatus on when you go to bed in the evening and take a reading after lying quietly in bed reading for 20 minutes to half an hour.

Take measurements in either way for five to seven days and you will have an idea of what your average resting heart rate is.

Another way in which your resting heart rate is useful is that it tends to rise if you are overtrained, ill or under a lot of stress, giving you immediate warning of these events, all of which make a difference to your training program.

Your maximum heart rate

You need to know your maximum heart rate because your training heart rate zone is worked out as a percentage of this.

There are several formulae around for calculating this, all based on age, since your theoretical maximum heart rate generally drops with age. However, in general, the lower your resting heart rate, the higher your maximum heart rate, so if you are a very fit 45 year old, your maximum heart rate may be more than the theoretical value. You will be able to tell this for yourself if you have set your training zone according to the theoretical value and you are hardly working up a sweat when you work out within these limits!

The most commonly used formulae are:

• For women: 226 - your age = age-adjusted maximum heart rate
• For men: 220 - your age = age-adjusted maximum heart rate

You can also measure your maximum heart rate using your normal type of exercise.

• General sporting activity - exercise at the highest pace you can maintain for two to four minutes taking your heart rate up to a level beyond which it doesn't increase. Repeat this after a ten minute rest. Maximum heart rate is the highest heart rate measured at the end of this period.
• Running - the so-called 12 minute test is a good one since it can also be used to see if your performance is improving. After warming up, run at an even pace for at least 10 minutes, then flat out for two minutes. Measure the total distance covered during the 12 minutes. As your fitness improves you should be able to cover a longer distance in the same amount of time. Your maximum heart rate is usually the highest heart rate measured towards the end of this period.
• Cycling - if using a flat road begin a ladder of 30 second intervals. At each 30 second step increase the speed of the bike by one km/hour. Using about four to eight steps in the ladder, your starting speed will then be about four km/hour slower than your fastest mid-distance speed. Your heart rate at this speed is your maximum heart rate. If using a hill or a series of hills, warm up first, then hit the bottom of the hill fairly fast. Work at going up the hill extremely hard until your heart rate readings no longer rise and you are getting exhausted. This value is your maximum heart rate.

Warning: if you have any kind of cardiac condition you should only determine your maximum heart rate in consultation with your specialist who will also recommend the heart rate zone within which you should exercise.

Training zones

Overall maximum training benefit is achieved by training at between 60 and 90 percent of maximum heart rate. If your heart rate monitor has the facility you can program these values into it and it will "beep" at you if you are above or below these values.

Training above 90 percent of maximum should only be carried out for short periods, for example in interval or speed training.

Training below 60 percent is reserved for recovery days, and, if you really need a recovery day, make sure that you stay at a lower heart rate throughout your workout, or you are not recovering at all.

In general

Work out your resting, maximum and training heart rates and get into the gym or on the road. You will be amazed at how knowing your heart rate allows you to monitor your training.

Start recording your average heart rate along with the other information in your training log so that you can begin to get an idea of your progress in getting fitter.