Once you determine the appropriate level of cardiorespiratory intensity, accurate monitoring of the intensity level ensures that the member reaches his or her fitness goals in the least amount of time. Numerous formulas are used to monitor exercise intensity. For our purposes, we’ve determined the following three formulas to be most effective:

1. Maximum Heart Rate Percentage (MHR)
2. The Karvonen
3. The Talk Test

How to Determine Heart Rate

1. Maximum Heart Rate

The complete formula for a 35-year-old exercising at 65-percent intensity is:

220 - 35 = 185
185 x .65 = 120.25
120.25 x 1.10 = 132

The formula for a 35-year-old exercising at 85-percent intensity is:

220 - 35 = 185
185 x .85 = 157.25
157.25 x 1.10 = 173

Note: 10 percent is added to the target heart-rate value to more accurately indicate the percentages of functional aerobic capacity.

2. The Karvonen Formula

This method measures the maximum heart-rate reserve. This formula is similar to the first, however the calculations include resting heart rate. The Karvonen Formula is one of the most popular methods of determining cardiorespiratory-intensity levels. The only difficulty with this method is the accurate determination of resting heart rate.

The complete Karvonen Formula for a 35-year-old exercising at 85-percent intensity is:

220 - 35 = 185
185 - 75 = 110
110 x.85 = 93.50
75 + 93.50 = 168.50

3. The Talk Test

The talk test is a subjective measurement of cardiorespiratory intensity. At low to moderate intensity, an individual should be able to breathe comfortably and rhythmically throughout the entire exercise session. At high levels of cardiorespiratory intensity (65 to 85 percent), breathing is significantly more strenuous than at rest. One is still able to talk, but finds it difficult to speak in full sentences.

The talk test measures perceived exertion and is considered a fairly accurate estimation of exercise intensity. It can also be used to harmonize calculated exercise heart rate with actual exercise intensity. Remember that the above two formulas are based on a predicted MHR and don’t take individual variances into account. For example, the Karvonen Formula calculates a heart rate (HR) of 168.5 beats per minute (BPM) to be 85 percent of MHR. If the member is still breathing comfortably upon reaching this HR, obviously 168.5 BPM is not high-intensity for this individual. The converse of this situation can also be a reality; make speed and/or load adjustments as necessary.

To reach fitness goals in the most effective manner, it is vitally important to exercise at the proper cardiorespiratory intensity.

How to Determine Pulse Rate

1. Place your index and middle finger around the inside of the wrist (about one inch from the top of wrist, on the thumb side).
2. Locate the artery by feeling for a pulse with the index and middle fingers. Apply light pressure to feel the pulse. Don’t apply excessive pressure as it may distort your results.
3. When measuring the pulse during rest, count the number of beats in 60 seconds. When measuring the pulse during exercise, count the number of beats in six seconds and add a zero to that number. Some factors that affect resting heart rate are digestion, mental activity, environmental temperature, biological rhythms, body position and cardiorespiratory fitness. Because of these variables, resting heart rate should be measured upon wakening or, at the very least, after five minutes of complete rest.

Note: Use of the carotid artery at the neck is not recommended for measuring pulse rate. Pressure on this artery reduces blood flow to the brain, which can cause dizziness and an inaccurate measurement.

How to Use a Heart-Rate Monitor

A heart-rate monitor is the most accurate method of measuring pulse rate. The most accurate models include a chest and a wrist unit. Monitors that attach to the ear or finger react to many movements and may provide inaccurate measurements.