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CYCLING PERFORMANCE TIPS

  Last updated: 8/21/2012

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 Maximum Heart Rate is based on the fact that it is a readily available surrogate for VO2max, the gold standard for assessing maximum exercise capacity and designing training programs.

I'm sure that at some point you have heard the mantra "MHR is 220 minus your age in years". However this is just a rough figure and much less accurate than a real life, on bike, determination. I ran across the following website which not only goes into detail about the various studies supporting MHR determination, but also provides a calculator that will serve you better than the 220 - age in years. After reviewing the various studies, they suggest the following calculation (quoted directly from the website).

To determine your maximum heart rate you could use the following, which combines the Miller formula with the research from Londeree and Moeschberger.

Just as we all vary in height and body habitus, everyone has their own personal maximum heart rate that is genetically "hardwired". Our maximum heart rate generally decreases one bpm (beat per minute) per year we age. Although the MHR of a teenager might be on average 220 beats per minute, for an individual this can vary +/- 11 beats per minute from that average (209-231 bpm). The same variation holds true as we age. Thus a 40 year old who would be expected to have a MHR of around 180 (220-40) could vary from 169 to 191 as his or her own personal MHR.

Maximum heart rates are "sport specific" i.e. they vary from one sport to another. Thus you cannot use your maximum heart rate from running to plan a cycling training program without risking overtraining. Cardiac hemodynamics and maximal sympathetic drive are influenced to some degree by 1) body position during exercise and to a significant degree by 2) muscle mass involvement. If an activity is restricted to upper-body muscle mass, peak heart rates will generally be considerably lower than in whole body activities (more muscle mass involved). For example, a triathlete with a max heart rate during running of 180, may only hit 176 on the bike, and 171 during swimming. To keep our terminology clear, it would be best if we call the running heart rate the "Maximal Heart Rate" and the highest heart rates observed in cycling and swimming, "Peak Heart rates” for each event. Knowing your peak heart rate for each discipline helps you to more accurately structure the intensity of your training.

Identifying your peak heart rate will help you identify your aerobic threshold for a particular sport. Trying to increase, or train, at your peak heart rate may lead to injury and over training. Finding your peak heart rate for each sport you are training for will help you set up your target zone heart rates (see next section) making your training more efficient.

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.

It is much more productive (in improving your cycling performance) to focus on how long you can hold your aerobic threshold rather than tiring yourself trying to improve your peak (maximum) heart rate. Your aerobic threshold (or lactate threshold) is about 12 beats below your maximum (84-90% of your MHR). Training at your aerobic threshold is useful because this is the pace you race at and can be sustained for 30 minutes or longer depending on your fitness. 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.

If you are interested in finding your personal peak (maximum) heart rate for cycling, the following on bike approach will give you that number. If you are overweight or have a family history of heart disease I'd suggest that you talk to your family physician or consult a cardiologist first.

Actual MHR - Warm up thoroughly (15 minutes on the flats). On a long, steady hill (doesn't have to be steep) increase effort every minute for at least 5 minutes until you can't go any faster (sitting, not standing). Then sprint for 15 seconds (it is OK to stand at this point). Stop, get off the bike (this is for safety reasons - not mandatory) and immediately check your heart rate, which should now be at its maximum. Count the number of beats for a full 30 seconds - then double that number (the doubled number should be your peak heart rate for bicycling in beats per minute. Similar results can be obtained on a stationary trainer.

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 fact that there is an increase in heart rate (and cardiac output) as the oxygen consumption of the exercising muscle increases, and the concept that there are benefits of applying variable stress to develop exercise tolerance in heart and skeletal muscle.

Metabolically, as exercise intensity increases and one moves up from one training zone to the next, there is a shift in the energy source for the skeletal muscle cells from fat to carbohydrates - below 70% MHR, fat is utilized preferentially. As MHR is approached, there is another shift towards anaerobic (without oxygen) metabolism which adds an increase in lactic acid production to the equation.

The Heart Rate Intensity Zones are generally 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.

I'd suggest that the optimal approach is to train below 80% of maximum heart rate (zones 1 to 3) on your easy days to build your aerobic base and is at a low enough stress level to facilitate muscle recovery. And then, when you have a good training base, push training to include several days a week above 85% MHR 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, but not hard enough to significantly improve your overall aerobic performance and increase your lactate threshold.

Training programs should be individualized, but once a good base is developed early in the season within Zones 1 and 2, most programs conform to the following general "rules".

TRAINING TIPS USING A HEART RATE MONITOR

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

USING A HRM TO AVOID OVERTRAINING

A heart monitor can provide you with clues as to whether you are risking an overtraining situation - and thus should take an extra day of rest. Do a warm up that takes you to the foot of a familiar hill. Climb at your usual pace while keeping one eye on your HRM. One of four things will happen:

  1. Heart rate is higher than normal and legs feel tired
  2. Heart rate is normal and legs feel tired
  3. Heart rate is higher than normal and legs feel good
  4. Heart rate is normal and legs feel good

In the first situation, your recovery from previous rides isn't close to what it should be. Head on home and take the day off. Pushing on will only put you in a deeper hole. In the second and third scenarios, your recovery is incomplete, but not to the extent of #1. You can continue riding, but only if you can keep distance and intensity moderate. Scenario number four indicates you are right on schedule with your training.

Your resting heart rate (RHR) is another indicator of your degree of training (and monitor for moving into an overtrained state). As you train, your resting heart rate should fall as 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 didn't win it needless to say however didn't 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%max hr. 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 perceived effort (pe), and then remove the heart rate meter during racing and ride on pe alone. "

THE BOTTOM LINE

The following question may help to illustrate a few points.

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. Here are a few thoughts-


Q. I am going to be training for the Paris Brest Paris in 2011 and would like to know how I can use heart rate or perceived exertion information to improve my training. The pace of brevets is only an average of 9.5 mph in order to get under the time cut off. Do you think need a HRM? M.M.

A. PBP is the ultimate endurance event. So cardiovascular training is not going to be the challenge as much as your musculoskeletal conditioning. You will probably be riding at 50 - 60 % VO2max most of the time and thus are burning a fair amount of fat calories as opposed to sprint type events. So no need to worry about intervals, and in fact as you are going to want to train at most somewhere around 70 - 75% VO2 max., I would go for "perceived exertion" that is "how you feel" as the best barometer. A HRM might drive you to do more than is necessary - and lead to burn out if you are only focused on training to the numbers.

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