It is crucial to gauge intensity during exercise because vigorous activity carries an increased risk of injury or accident. Frequent moderate-intensity exercise realises optimum benefits without increasing the risks.
Research shows that several short bouts of as little as 5 or 10 minutes at between 40 and 50% of your maximal oxygen uptake (VO2 max) may be beneficial.
To establish VO2 max a maximal exertion exercise assessment is needed, which requires maximum motivation, specific equipment, and skills to interpret the data. Obviously this does not suit everyone and so other methods of establishing appropriate exercise intensity have been developed.
These include a rate of perceived exertion scale and also age-adjusted predicted maximal rates where the basic formula of (220 - age) can be used.
Heart rate monitoring
As a rough guide, cardiovascular exercise should increase the heart rate to between 70-80% of its maximum. But older adults just starting exercise will notice benefits at much lower rates, such as between 40-50%.
For example, a 50-year-old who wants to complete some cardiovascular exercise should conduct the following calculation:
220-50 = 170
70% of 170 = (70 x 170/100) = 119
So any activity that raises the heart rate to approximately 119 beats per minute would provide the body with a suitable intensity to improve cardiovascular fitness.
Fat-burning exercise relies on a lower heart rate (between 40 60% of maximum) to achieve the desired results. Using the calculation above, a heart rate within the range of 80 105 beats per minute for a 50-year-old would provide a level of intensity suitable for fat burning exercise.
Use the following table as an approximate guide to the heart rate required during exercise at different intensities.
Remember that some individuals can have an actual maximum heart rate 20 beats per minute higher or lower than that predicted and that taking your heart rate accurately can be difficult, especially during exercise. Using a heart rate monitor can help establish your appropriate exercise intensity.
Consequently, it may be advisable to use a rating of perceived exertion (RPE) since individuals possess a well-developed system for sensing the strain involved in physical effort.
Rate of perceived exertion (RPE)
RPE is especially useful for people who are taking medication (such as beta-blockers) which affects their heart rate response.
Many different versions of Borgs original RPE exist. Basically, the scale should start at 6, which is no exertion at all , and go up to 20, which is maximal exertion . Normally the value of 6 equates with a heart rate of 60 and so on. For example, if you gave a value of 11 and then measured your heart rate you should find it would be in the region of 110.
After time you should be able to estimate your exercise intensity with accuracy. Then you might use other indicators such as whether whilst exercising you can whistle (RPE 6), sing (RPE 10), talk (RPE 14) or are gasping for breath (RPE 18).
Another simple way to estimate your exercise intensity is to set out a level walking course of just half a mile. Time how long it takes and use the guide below to see what exercise intensity you were walking at.
If it took more than 10 minutes LIGHT
If it took between 10 7 ½ minutes MODERATE
If it took between 7 ½ - 6 minutes VIGOROUS
It is a good idea to use this timed walking guide when learning how to use the RPE to estimate your exercise intensity. After a while you should be able to exercise at the right intensity without watching your heart rate or the clock.
Calories
All forms of physical activities or exercise aim to strike a balance between energy intake and expenditure.
The following chart shows the amount of calories that can be burnt in one hour whilst doing the following activities.
02/06/2009