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Monitoring Excercise Intensity

By Beth Greenaway

Following on from the last article on beginning an exercise programme, I am going to introduce you to methods of monitoring your exercise intensity so that you will be doing your heart the most good.

The Talk Test

The first, and least accurate, method of monitoring exercise intensity is the 'talk test'. The goal is to work out at a level which enables you to answer a question, but not comfortably carry on a conversation. You are working too hard if you have to gasp between every few words, or too easy if you can reach the end of a sentence before taking a breath. During exercise, the conversation will be easy at low levels, jerky at moderate levels, and almost impossible at high levels.

This method is very subjective and therefore rather imprecise. Monitoring your heart rate is the most accurate way to measure exercise intensity, and the safest way to make sure you are doing the most good for your heart and fitness levels, without overdoing it. You can monitor your heart rate by taking your pulse, or electronically with a heart rate monitor. With either method, you first need to know what your target heart rate should be.

Calculating A Target Zone For Your Heart Rate

To calculate your optimal heart rate for productive exercise, you need to know your actual or estimated maximal heart rate (MHR). You may already know this from the results of a graded exercise stress test (supervised by your cardiologist). If not, you have to estimate it using the simple formula of 220 minus your age.

For example: If you are 30, your estimated MHR will be 220 - 30 = 190 bpm (beats per minute).

Once you have an idea of your maximum heart rate you can calculate the target heart rate zone you should use for exercise. Your target heart rate zone is the upper and lower heart rates between which you productively gain fitness. When you first begin exercising, a target heart rate zone between 50% and 60% of your maximum heart rate will probably be sufficient. As you gain fitness, a target range of 60% to 70% of the maximum would be more appropriate.

For example: For the same 30 year old person used above, the 60% to 70% heart rate zone would be between 114bpm and 133bpm.

A more accurate method of figuring the most productive exercise heart rate is calculated using the Karvonen Formula, or percentage of heart rate reserve. This takes into account your current fitness level as it includes your resting heart rate (RHR), which should decrease as your fitness improves. For a full explanation of the Karvonen formula see the web site listed at the end. Having estimated your appropriate target heart rate zone, it is important for you to check that you are actually working at that level during exercise.

Heart Rate Monitoring

The best method for checking your heart rate is to use a heart rate monitor, which you can purchase from a sports shop. The accurate ones consist of a strap worn around the chest, and a wrist watch with a readout. You get continuous feedback and the better models can be set to sound an alarm if you are exercising to hard, or not hard enough.

If you don't have a heart rate monitor, then stop exercising briefly and take your pulse for 10 or 15 seconds. Multiply the number by 6 or 4 respectively to get your beats per minute. Try not to take your pulse for longer, as your heart rate should drop rapidly once you stop exercising, and the result will be inaccurate.

Monitoring Your Exercise

Remember not to start with a rush. Slowly warm up for at least the first 10 minutes. Gradually increase your intensity until you reach the lower end of your target heart rate. Once there, continue your aerobic work out for between 10 and 60 minutes, depending upon your fitness level. For a beginner 10-20 minutes will be enough to elicit fitness gains (Examples of an aerobic workout are cycling, swimming or brisk walking). Follow this with a minimum of a 10 minute cool down, to allow your heart rate to gradually return to near its resting level. For maximum fitness benefits repeat your workouts 3-5 times per week.

Remember that although it is necessary to exercise at moderate intensities to improve cardiovascular fitness, working out at lower intensities still has physical and mental benefits. While exercising, remember to drink and to monitor yourself for signs of over-exertion such as extreme breathlessness, dizziness, unusually irregular pulse or chest pain. If you experience any abnormal symptoms, consult your doctor before exercising again.

Issues And Limitations

Prior to beginning any exercise programme it is vital that you talk to your consultant. Some medications prescribed to GUCH patients, such as beta blockers or calcium channel blockers can have an influence on your heart rate. On medication, your target heart rate could be much lower than the above formulas would suggest, making it difficult or risky for you to reach your numerically calculated heart rate zone.

Make a point to ask your consultant if this applies to you, as it may be more appropriate for you to use a Rating of Perceived Exertion (RPE), to assess exercise intensity. There are two RPE scales devised by Borg, with the most common having a scale ranging from 6 to 20. The second one, with a 1 to 10 scale is sometimes used in gyms and cardiac rehab programmes. (More details on Borg RPE scales can be found on my web site- see below). Once you have gained approval from your cardiologist, and established your target heart rate zone or rating of perceived exertion, you should be able to begin exercising safely.

More Information

If you have other questions relating to exercise for GUCH patients please contact me directly: beth@merlinfitness.com

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