Dr. James Allen Watrous, Ph.D.

            How to properly compute your heart rate range (or reservoir), so you can determine the proper heart rate range for your level of fitness.

            Your resting heart rate and your maximum heart rate are a function of your fitness level and your genetic pole.  That is, two people can be at the same fitness level and have different resting and maximum rates.  As your fitness level improves, your resting rate will decrease and your maximum rate will increase.  The resting rate will decrease to a specific point and then level off depending on your genetics.  Similarly, the maximum rate will increase to a specific point and level off. 

            The difference between the resting rate and maximum rate is the range or reservoir you have for a given level of fitness.  The resting rate is best determined by counting the number of beats for fifteen seconds and multiplying by four.  The best time to measure resting heart rate is before you get out of bed in the morning.  For example, if you count 14 beats in 15 seconds, then your resting heart rate is 56 beats per minute.  To get your maximum heart rate is to have a supervised stress test on a bicycle if this is your primary form of exercise.  The stress test should always be done with the primary form of exercise.  A VO2 max test generates even more information if you are interested in upper levels of fitness.  If you are in good health as determined by medical exam in the last year, then you can simulate a stress test by riding up a long steep hill (after an appropriate warm up) as hard as you can until your respiration goes out of control.  Stop and count the heart rate for fifteen seconds.  Repeat every minute for five minutes.  IMPORTANT!  Always do this with a friend and never by yourself.  For those just starting out, a reasonable approximation is to take 220 minus your age.  Since individuals vary greatly, this approximation may turn out to be crude.  However, you need a starting point now.  Remember that the resting and maximum heart rates change as fitness changes and this process will have to be repeated until your fitness level is where you want to be.

            For example, your resting heart rate is 50 beats per minute and your maximum rate is 175 beats per minute.  Your heart rate range or reservoir is 175 - 50 = 125 beats per minute.  Let us suppose that you want to do an aerobic level of exercise at 60% of your heart rate range (reservoir).  Then here is the proper way to compute that value.

            Workout Heart Rate = Resting Heart Rate + (60%)X( Heart Rate Range )

            In this example: Workout Rate = 50 + (60%) X (125) = 50 + 75 = 125

                                              Workout Rate = 125 beats per minute.

Let us assume you have a heart rate monitor and want set two values that are plus and minus 5% of the 60% workout rate.

Upper Workout Rate = 50 + (60%+5%)X(125) = 50 + 81 = 131;

Lower Workout Rate = 50 + (60%-5%)X(125) = 50 + 69 = 119.

You would set your heart rate monitor to these upper and lower values.  Now try to maintain your heart rate value between these levels.  On the average you would be doing a 60% workout in the aerobic region of the human body's utilization of energy output.

The cross over between aerobic and anaerobic forms of energy output varies from individual to individual, but 75% to 80% of your heart rate range is a good cross over value to use.  (Remember to add your resting heart rate to this cross over value from the heart range.)  No one can maintain an anaerobic energy output for extended periods.  The duration of such output depends on your fitness level and genetic pole.  However, there is an upper limit for all individuals.

At aerobic levels of training, fat can be reasonably used for energy source as well as carbohydrates.  Even protein can be utilized as an energy source.  However, it is not an efficient source of energy.  At anaerobic levels of training, mostly the glycogen forms of energy that are primarily stored in the liver as well as lesser amounts stored in the muscles can be utilized for energy output.  There is a limit to the amount of energy an athlete can store even though the amount does vary with fitness level.

You have heard about the runnerís wall.  The runner simply runs out of energy assuming that the runner has not ingested food.  In a marathon this is near mile twenty (20).  In bicycling this is usually near mile eighty (80).  The actual point will depend on the conditioning of the individual (fitness level).

Technically, aerobic energy output is with the utilization of oxygen and anaerobic energy output is without oxygen.  These two processes are quite different and generate different by-products in the human body.  The aerobic forms of energy output can be sustained for long periods of time, as long as the person continues to eat and drink water.  A good example of extended aerobic energy output is the cyclists competing in the Race Across America.  This is an extreme example, but within the humans ability to accomplish.


Copyright, 2017, 1985 to 2017. Watrous' Cycling Enterprises