CYCLING PERFORMANCE TIPS

HEART RATE MONITORS

CONTENTS

The Heart Rate Monitor (HRM) is touted by many cyclists and trainers as the most significant training advance in the last ten years. Although many coaches refuse to work with an athlete without the physiologic training information it provides, HRMs have their detractors. And that small backlash is slowly growing. An alternative to a HRM, not quite as technical and rigid, uses perceived effort as a measure of your level of exertion.

BASIC CARDIOVASCULAR PHYSIOLOGY

First, let's review the basic physiology of the circulatory system asking ourselves the question "What does the heart rate really indicate?" The components of the cardiovascular system are: With every heart beat (contraction of the heart pump), a certain amount of blood (stroke volume) is pushed through the system. The contraction frequency of the heart is the heart rate (HR). The amount of blood moved to the cells of the body every minute is the product of the heart rate and stroke volume (HR x strove volume).

With physical activity (exercise) more oxygen is required by the muscle cells, and the circulatory system responds by increasing the heart rate (and the cardiac output). With aerobic training, the actual amount of blood pumped per heart beat (stroke volume) increases and the efficiency of the exchange process at the capillary level improves. The result is a lower heart rate for any level of physical activity in the trained versus the untrained individual. Thus aerobic training benefits include:

The training effect results when the heart muscle is "stressed" by an increase in cardiac output (just as muscles in the arms and legs respond to the stress of lifting free weights). As the cardiac output is directly proportional to the heart rate, a heart rate monitor (HRM) can be used to structure and monitor an aerobic training program. (For additional background see Basic Exercise Physiology - the cardiac system.)

Let's look at the pros and cons on the use of a HRM.

PROS AND CONS

The ADVANTAGES of a HRM include its use:

The DISADVANTAGES of a HRM are:

DEFINITIONS

Here are some definitions you'll encounter in the literature on heart rate monitors:

* Determining your actual Anaerobic Threshold (synonyms are lactate threshold, AT, LT, Concini test). Accurate laboratory determination of your anaerobic threshold requires frequent blood draws while pedaling an ergometer at steadily increasing workloads. But for training purposes, the following approach is an alternative. Using a single gear, start cycling at 35 kph. Slowly increase speed on a flat course by 1km/hr every 300 meters (1/5 mile). Chart heart rate vs speed. Anaerobic Threshold is the "breakpoint" where heart rate levels off relative to speed.

Let's assume you have decided to use a heart rate monitor in your training program. The first step is calculating your MHR or maximum heart rate.

CALCULATING YOUR MAXIMUM HEART RATE (MHR)

Interest in the MHR is based on the fact that it is a readily available surrogate for VO2max, the gold standard for assessing exercise capacity and and designing training programs.

Just as we all vary in height and body habitus, everyone has their own personal maximum heart rate genetically "hardwired". Our maximum heart rate also decreases approximately one bpm (beat per minute) per year. The average MHR of a teenager is 220 beats per minute, but this may vary +/- 11 beats from the average (209-231 bpm). For example, a 40 year old who would be expected to have a MHR of 180 (220-40) could vary from 169 to 191 for his or her own personal MHR.

Another key point is maximum heart rates are "sport specific" i.e. they vary from one sport to another. For a given rate of oxygen consumption, weight bearing activities such as running raise the heart rate more than cycling (part of your weight is supported by the bike). So you cannot use your maximum heart rate from running to plan a cycling training program without risking overtraining.

One of the following two approaches can be used to determine your MHR for cycling. The first is more accurate and the one I prefer. There can be marked discrepancies between the estimated MHR and real life results (up to 5% of the population can have heart rates 20 beats above or below the ESTIMATED figure). And if you are in shape, the typical decline of one beat per minute per year doesn't always hold.

The only limit to the length of time one can ride at 100% of their MHR is personal discomfort. This level of activity does not "strain" the heart muscle or have other harmful effects on the heart itself. Although this level of activity might be considered in a competitive race or event for a short sprint, maximizing the benefits of a training program is the result of a mixture of recovery and hard days (see below). As the time you can hold 100% MHR is considerably shorter than the time you can ride at 84-90% MHR, the art of racing is finding the right mix to get you to the finish line first. Most competitive athletes train at their lactate threshhold (84-90% of their MHR).

HEART RATE TRAINING ZONES

There are 5 training "zones" or heart rate ranges. These are arbitrary divisions and can differ from article to article or coach to coach. They are based on the increase in heart rate (and cardiac output) as the oxygen consumption of the exercising muscle increases, and the concept of the benefits of variable stress in developing the exercising muscle (heart or skeletal). As one moves up the hierarchy of training zones, exercise intensity increases and there is a shift from the use of fat as an energy source for the muscle cell to carbohydrate (below 70% MHR fat is burned preferentially). And as the MHR is reached, there is a shift in the muscle cell towards anaerobic (without oxygen) metabolism with increased lactic acid production.

The Heart Rate Intensity Zones are divided as follows:

If you always train at low heart rates, you will develop endurance with no top end speed. Conversely if you train hard most of the time, you'll never recover completely and chronic fatigue will poison your performance. The solution is to mix hard training with easy pedaling in the proper proportions.

The best approach is to stay below 80% of maximum heart rate (zones 1 to 3) on your easy days to build an aerobic base while allowing day to day recovery, and then push above 85% when it's time to go hard to improve your high level performance. But avoid training in the no man's land or mediocre middle at 80-85% of MHR where it's too difficult to maintain the pace for the long rides needed to build endurance and allow some recovery time, but not hard enough to significantly improve your aerobic performance and increase your lactate threshold.

Training programs should be individualized, but once a good base is developed early in the season with Zones 1 and 2 exertion, most programs contain the following elements.

TRAINING TIPS USING A HEART RATE MONITOR

Tips for a training week: (see also mileage tips and training options)

RESTING HEART RATE

Your resting heart rate (RHR) can also be used as an indicator of your degree of training. As you train, your resting heart rate will fall. This is a result of the increased efficiency of the circulatory system. The heart will increase the volume of blood pumped per beat, and the peripheral muscle cells will become more effective at extracting oxygen from the blood passing through their capillary networks. The RHR for an untrained individual is 60 to 80 beats per minute. With training, it is not uncommon to see the RHR fall into the high 40s or low 50s. And as mentioned above, regular monitoring of your resting heart rate in the mornings (before getting up and beginning your daily activities) can be used as a monitor for overtraining (heart rate on awakening and before getting out of bed 10% higher than your personal normal for several consecutive days).

SLOW HEART RATE

A slow heart rate is considered a sign of good health. As one conditions, the heart will beat more slowly for any specific level of activity - including at rest. That is why the resting heart rate is a good measure of cardiovascular conditioning. The two exceptions are hypothermia, where a slow heart rate is a reason for alarm, and the other is a heart rhythm disorder. The latter can indicate heart disease, generally comes on quite suddenly, and is occasionally associated with an irregularity of the pulse.

AN OPPOSING OPINION

But there are differences of opinion on the usefulness of a heart rate monitor for training and competing. So keep an open mind and don't consider the HRM as the only real key to success. The following is from an Aussie coach, Graham Fowler:

"I have observed a number of different %max heart rates during time trials. My nephew once rode a junior nationals ITT at 100%MHR. He didnt win it needless to say however didnt crack either. Obviously he was very fit or his MHR was inaccurate. I advise riders to ride just above (1 to 5 beats per min) what they consider threshold. This is around 92%mhr. This mark needs to be derived in training. I am aware of race day anxiety causing the heart rate to elevate somewhat so the hr is not such a good measure with an anxious rider. I am more inclined in the future the train with heart rate to establish a perceved effort (pe), and then remove the heart rate meter during racing and ride on pe alone. The speedo is then the govener (sic)."

THE BOTTOM LINE

The following question reflects one that I often receive:

Q:I am 48 years old and a new MTB biker. I am working to keep/improve my shape in a controlled way, so I am using a HR monitor on my MTB bike. Until now I used Max HR of 180, just because quite often I reached this figure. Last time after accelerating my HR for 15 minutes, on a mountain steep trail I reached (for more than a minute) a HR of 182 -185 (in total it was 3 minutes of 8.7% trail with avg. speed of 8 km/h, avg. HR of 178 and max of 185) and I could continue without a problem with the trail.

My questions are:

A:My opinion:

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