Individuals respond to exercise in different ways. This is one of the reasons for using a monitor to determine heart rate (rather than using tables and charts). Under a constant workload, the heart rate of a fit person increases more slowly than that of an unfit person. Differences in skill and technique during exercise also affect heart rate, and a person's heart rate can vary from day to day. Other factors affecting max heart rate include age, gender, stress, disease and fitness level, along with genetic factors.

Heart rate monitoring is based on maximum heart rate. A simple method to figure out your client's maximum heart rate is as follows:

For males, take 220 (theoretical maximal heart rate) age = age-adjusted maximum heart rate.

For females, take 226 age. (The higher theoretical maximal heart rate for women is to accommodate for the smaller female heart, decreased stroke volume and smaller blood volume.)

People experienced with using heart rates may use a different formula, which accounts for resting or morning heart rate. This allows for training adjustments to be made on a daily or weekly basis. With this formula, you need to know your actual maximal heart rate.

Designing programs

Once the maximal heart rate of your client has been determined, an appropriate cardiovascular program can be developed. Consider the following factors when developing and implementing a heart rate monitor program:

Intensity. During aerobic exercise, intensity level is determined by the speed and type of movements, as well as the muscle mass involved. A fast tempo makes the exercise more strenuous. Adding active muscle mass (for example, adding arm movements or hand weights) during exercise increases the intensity.

Mode. The mode, or type of exercise, should be determined by the current condition of the individual, goals and equipment available.

Duration-frequency. Studies show that more frequent, shorter bouts of cardiovascular activity can be more beneficial and less dangerous than less frequent, longer bouts of exercise. Minimal levels might include 30 to40 minutes of aerobic activity five to six times a week.

Body position. Heart rate is lowest when lying down, and highest when standing, because of the work required to return the blood through the veins to the heart. Keep this in mind during cool-down, when programs typically involve floor work.

Environmental factors. High temperatures and/or humidity increase heart rate; low temperatures may also alter the heart rate. A 1-percent decrease in hydration may vary the heart rate by as many as five beats per minute.

Stress. The heart rate, both at rest and during exercise, is generally elevated in the overworked body. Excessive exercise may cause excess fatigue and stress. Lack of sleep and the demands of family, study and job may also influence heart rate.

Medication. A number of drugs used to treat heart disease, hypertension, asthma, coughs, and stress or anxiety can accelerate or decelerate heart rate. Refer to ACSM's drug guide for specifics.

Upper-body exercise. Typically, heart rates for upper-body activities are 10 to15 beats lower than for lower-extremity activities.

Heart rate training zones

Based on a percentage of maximal heart rate, have your clients aim for the following heart rate percentages for each type of exercise mode:

Anaerobic or interval work: 85 to 95 percent of max heart rate

Lactate threshold or anaerobic threshold work: 75 to 85 percent of max heart rate

Tempo work: 65 to 75 percent of max heart rate

Recovery work: 55 to 65 percent of max heart rate

Weekly activities using a heart rate monitor can be based on heart rate zones. For example, 75 percent of activities can be performed in the recovery heart rate zone; 15 percent in the tempo heart rate zone; 5 percent in the lactate/anaerobic threshold heart rate zone; and 5 percent in the anaerobic heart rate zone.

For a high-performance walking program using heart rate zones, exercisers should work hard enough to get their heart rates into the 80 to 90 percent of maximum zone, one to three times per week. The idea is to force their bodies into taking in and circulating a large volume of oxygen, and to teach their muscles to use that oxygen efficiently.

Sample walking workouts

Following are some sample workouts used by recreational walkers. Have your clients and members try them as is, or modify them to meet their schedules and fitness levels. (Also see Tables 1 and 2.)

Tempo walks. After a 10-minute warm-up at 60 to70 percent max heart rate, have them walk for 20 to30 minutes at approximately 85 percent of max heart rate, or 10 beats below their anaerobic threshold. Have them cool down for 10 minutes.

Lactate threshold intervals. After a sufficient warm-up, have clients walk three times for eight minutes, or three times for two minutes at 90 percent max heart rate. Have them repeat this routine four to10 times, allowing their heart rate to drop 20 beats between intervals.

Recovery walks. Have clients walk 60 minutes or longer at 55 to60 percent max heart rate, or 20 to30 beats below their anaerobic threshold. Remember, this is a recovery and walkers should not exceed the recommended heart rate.

Use in classes

To make group exercise safer and more effective, and to avoid driving participants to intensities beyond their capabilities, incorporate heart rate monitoring into your group programs. Providing monitors for your members to use during a class can encourage heart-rate appropriate conditioning. Instructors can encourage participants to purchase a monitor for use during their outside activities.

Guiding members

Once your clients and members are introduced to heart rate training, their exercise sessions can be more productive, more motivating and can carry more meaning as far as monitoring improvements. If you are looking for another way to motivate and retain your members, heart rate training just may be the answer.

High-Intensity Concerns

Exercise provides people with multiple cardiovascular benefits, but it also carries risks. Sudden cardiac death, which kills an estimated 225,000 Americans each year, and acute myocardial infarction are the most important cardiovascular complications of exercise based on both frequency and seriousness. To avoid working out at intensities that are too high, exercisers can wear a heart rate monitor and stay within a safe exercise zone.

Graded Exercise Testing