Maximal heart rate is a specific value: the maximal number of times the heart can contract in one minute. As a teacher, you need to know and explain to your students the following facts about MHR:

• It is genetically determined—that is, you are born with it.
• It is a fixed (absolute) number that does not decline with age unless you become unfit.
• It cannot be increased by training.
• It is not an indicator of current fitness.
• In young children, it is often measured at over 200 bpm.
• It tends to be higher in women than in men.
• It is affected by drugs.
• It is not fully developed until after puberty.
• It is not a predictor of athletic performance.
• It varies greatly among people of the same age.
• For most people, it cannot be accurately predicted by any mathematical formula.
• It does not vary from day to day, but it is test-day sensitive based on physical impacts that day, such as drugs or illness.
• Testing should be conducted multiple times to determine the correct number.
• It is sport specific.
• It is the basis for setting personal heart zones.

Measuring Maximal Heart Rate

Maximal heart rate is the best index to use in setting individual heart zones. Because it serves as the principal marker for exercise intensity, your students will anchor their heart zones around MHR.

There are a number of approaches to measuring this value. Fit people, under the supervision of a qualified instructor, sometimes undergo a maximal heart rate test, which involves exercising to the point of fatigue in two to four minutes to determine their true MHR number. Exercise intensity is increased regularly until the person cannot continue. In this program, however, students will take a series of submaximal heart rate tests and undergo an assessment below maximal effort, and then use the results to predict MHR.

MHR is sport specific. It is affected by factors such as the type and amount of muscle used, body position, and environment (e.g., water versus land). Following are some of the factors involved in determining the specific maximal heart rate for various sports:

• Body position
• Size and number of muscle groups involved in the activity
• Ambient temperature of the environment
• Type of activity, such as weight-bearing sports (e.g., running)
• Use of equipment (e.g., wheels in cycling).

Some of the lowest MHRs are recorded for swimming (a sport in the prone position), activities done in colder ambient temperatures, and activities that use the smaller upperbody muscle groups. The highest MHRs are recorded for weight-bearing activities (e.g., cross-country skiing), activities that use the large muscles of the body, and activities that use both the upper- and lower-body muscle groups. People who work out in multiple sports need to determine their MHR for each because it varies by sport. However, the HZE program uses a global, all-sport MHR to set zones, which is easier for teachers and students to follow. A global MHR is accurate enough to use for all sport disciplines in the school environment.