Find Your Individual Exercise Zone

In an effort to come up with a scientific way to improve physical conditioning, cardiologists and exercise physiologists rely on information provided by heart rate monitors. A heart rate monitor allows you to know your heart beats per minute (bpm) and is used as a tool for regulating intensity of workouts. A transmitter belt worn around the chest detects an electric signal originating from your heart and sends this signal to a wrist receiver where heart rate information appears.

The more fit you are, the more blood (and oxygen) your heart is able to pump per beat. As a result, your heart does not have to work as hard to carry the same amount of oxygen to the muscles as a less fit person.

Monitoring the heart for training purposes depends upon knowing your maximum heart rate (HRmax). HRmax is the highest number of bpm achieved in an all-out effort.

Finding Your Maximum Heart Rate

The Haskell formula, 220 minus your age, is the most used formula to estimate HRmax. The generally accepted error is + 10-12 bpm, which is due to different inherited characteristics and exercise training. Which means this formula is only a guideline to start with. It is not accurate!

Dr. William Haskell devised this formula. He was trying to determine how strenuously heart disease patients could exercise. In preparation for a medical meeting, Dr. Haskell culled data from about 10 published studies in which people of different ages were tested to find their maximum heart rates. The subjects were never meant to be a representative sample of the population. Most were under 55 and some were smokers or had heart disease.

Sally Edwards, a leading author on heart rate fitness uses: males - 210 minus 1/2 your age minus 5% of your body weight + 4, females - 210 minus 1/2 your age minus 5% of your body weight

Warning! A third method of finding your HRmax, and the only real way to determine it, is under laboratory conditions by a cardiologist or exercise physiologist.

Individual Training Zone

Once you have your maximum heart rate you can now apply it to your exercise/training with the use of a monitor. Training zones are established to categorize your fitness. I have seen more than six zones used, but prefer the “standard” five zones. These five zones are divided between 50% and 100% of your maximum heart rate in 10% increments. The following table shows the five zones and how they affect you. You could even use this table in place of a monitor.

	Zone 5	Zone 4	Zone 3	Zone 2	Zone 1
Breathing	very forced breathing	forced breathing	talking is hard	can converse	can sing*
Feeling	burn/pain	steady	steady/light	easy	very easy
Benefit	Strengthens heart	Burns high % Fat	Enhance Heart Strength	Improves endurance	Improve performance
* Some of us but not me.

Training Zones Benefits

Zone 1 - under 60 % of Maximum Heart Rate

This training zone is the lowest intensity, yet is quite beneficial to both physical and mental well being. Exercise 3 - 4 times per week for a minimum of 30 minutes in your zone to realize a stronger cardio-vascular system and a better awareness of the world.

Zone 2 - 61 - 70 % of Maximum Heart Rate

This zone changes how efficient your heart is and begins to train your muscles. Body fat is the primary source of energy utilized. This is good for long slow distance training as the body becomes more efficient at feeding the working muscles more.

Zone 3 - 71 - 80 % of Maximum Heart Rate

Zone 3 strengthens the heart and lungs, increasing your ability to exercise for longer periods with less effort. Athletes, who wish to increase their strength and endurance, while burning a greater number of calories, use this zone. This zone is still within the body’s oxygen intake capabilities and can be maintained for a long period.

Zone 4 - 81 - 90 % of Maximum Heart Rate

Zone 4 is oriented toward the competitive athlete who wants to build greater speed and power. It is at or above the individual’s oxygen intake ability, creating oxygen debt and lactic acid increase in muscle tissue. It is in this zone that you feel the “burn” of hard exercise, and this zone can be maintained only for short periods.

Zone 5- 91 - 100 % of Maximum Heart Rate

At 90-100% of your maximum heart rate, you may be doing more damage to your body than you are helping it. In this zone, lactic acid develops very quickly, as you are operating with oxygen debt to the muscles. You will not be able to maintain this level very long and it should be used for intervals or sprinting workouts.

Determine Your Training Zones

Choose any zone in which you would like to train. Calculate your lower and upper heart rate limit for that zone by multiplying your HRmax by the percentages listed for that zone. For example, if you want to ride/train in Zone 2, multiply your HRmax by 70% and 61%. Using the Haskell formula, at 40 years of age, you would want to train within the range of 126-110 bpm. See table below.

Haskell Formula		Zone 5	Zone 4	Zone 3	Zone 2	Zone 1
220 - your age		100-91%	90-81%	80-71%	70-61%	60-51%
220-30	190	190-173	171-154	152-135	133-116	114-97
220-40	180	180-164	162-146	144-128	126-110	108-92
220-50	170	170-155	153-138	136-121	119-104	102-87
220-60	160	160-146	144-130	128-114	112- 98	96-82

A formula used to determine heart rate zones is the Karvonen formula. With this formula, you need to determine your resting heart rate (HRrest) as well as know your HRmax. To find your HRrest: take your resting heart rate over three days and average it.

Karvonen formula: ((HRmax – HRrest) * zone percentage) + HRrest.

Comparison of Formulas

The table below is a comparison between the Haskell formula, the Edwards formula, my actual HRmax, and the Karvonen formula. I have found the Karvonen formula is the closest to my personal experience on the bike in terms of HRmax, bpm, and training zones. In fact, Polar Heart Rate manufacturer recommends using the Karvonen formula.

	HRmax	HRrest	Zone 5	Zone 4	Zone 3	Zone 2	Zone 1
			100–91%	90–81%	80–71%	70–61%	60–51%
220-63*	157		157-143	141-127	126-111	110- 96	94- 80
Edwards	174		174-158	157-141	139-124	122-106	104- 89
HRmax	178**		178-162	160-144	142-126	125-109	107- 91
Karvonen	178**	60	178-168	167-156	155-145	144-133	132-122
*my age	**HRmax as determined in a stress test

Which Heart Rate Monitor to Buy

Heart rate monitors can range from ~$50.00 (on sale) to over $400.00. The more expensive monitors include more functions, like being able to download data to a computer or combined heart rate monitor and bike computer. I prefer the least expensive with all the basic functions. You can go to the web to compare different models.

A caution with the chest strap: be sure you can change the battery in the strap. If you cannot change the battery, then you will have to return it to the manufacturer for replacement. They will replace the strap (not replace the ~$3.00 battery), and charge you ~$40.00 or the cost of a new strap.

My recommendation would be to search the web for articles on heart rate monitors, articles by Sally Edwards, and articles about the Karvonen formula. If you decide to get a monitor, use it as a tool. Enjoy it and your bike.