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CYCLING PERFORMANCE TIPS

  Last updated: 12/6/2009

HEART RATE MONITORS


CONTENTS

• Basic cardiovascular physiology
• Pros and cons of using a heart rate monitor
• Definitions
• Calculating your maximum heart rate
• Heart rate training zones
• Training tips using a heart rate monitor
• Resting heart rate
• An opposing opinion

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:

• the heart (the pump)
• the arteries (a distribution system)
• the capillaries (the exchange system where gases, nutrients, and other chemical compounds move to and from surrounding tissue
• the veins (which are the return circuit)

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:

• a lower resting heart rate
• a lower heart rate for a specific level of exertion
• an increased exercise capacity at an individual's maximum heart rate.

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:

• as a motivational tool - like a coach ; brings objectivity to a training program.
• to teach beginners to read their bodies and avoid anaerobic overtraining.
• to aid in doling out energy during time trialing or climbing, saving some for the final effort.
• to analyze race efforts and design a personalized training program.
• to spot overtraining (heart rate 10% higher than normal on awakening for several consecutive days).

The DISADVANTAGES of a HRM are:

• its inconsistency - at the same heart rate you're not always putting out the same effort day to day.
• the lack of scientific support - there is no evidence training with a HRM improve competitive performance.
• too much data, esp with elaborate HRMs, with little agreement on how to use this information to improve training or performance.
• the lag time in heart rate response to a change in exertion - 15 to 30 sec lag with 2 to 3 min to stabilize at the new level of exertion.
• its incompatibility with group training.
• it distracts from dangerous road hazards.

DEFINITIONS

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

• bpm - beats per minute
• Max HR (MHR) - maximum heart rate (expressed in beats per minute)
• target heart rate - the training heart rate (usually a range of values)
• anaerobic threshold (AT)* (synonymous with lactate threshold). Lactate production occurs with muscle cell activity and increases as activity becomes more vigorous. Lactic acid is metabolized by the muscle cells, but at some point they cannot eliminate (or oxidize) the lactate as fast as it is being produced and the blood lactate level begins to increase. In trained athletes, this threshold for lactate buildup occurs at a higher activity level or percentage of the athlete's MHR or aerobic capacity. For all practical purposes, the AT is the highest heart rate you can maintain for a race or hard ride lasting up to an hour. As the AT increases with aerobic conditioning, it is considered one of the standard measurements to track training. The AT is usually reached at 80-90% of your maximum heart rate, but in elite riders rises to 90-93% of their maximum heart rate.(See also Basic Exercise Physiology - measures of cardiovascular fitness.)
• lactate threshold (LT). See anaerobic threshold.

* 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 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.

• Warm up thoroughly (maybe 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 at its maximum for a full 30 seconds - then double that number. This will give you a practical maximum heart rate in beats per minute. Similar results can be obtained on a stationary trainer.
  
• 220 minus your age in years. A rough figure and much less accurate than the on bike approach.

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 threshold (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:

• Zone 1 65% of MHR (recovery rides)
• Zone 2 65-72% of MHR (endurance events)
• Zone 3 73-80% of MHR (high level aerobic activity)
• Zone 4 84-90% of MHR (lactate threshold(LT,AT); time trialing)
• Zone 5 91-100% of MHR (sprints and anaerobic training)

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)

• one long recovery ride - zone 1 or 2
• one long day (event distance + 10 to 20%) - max hr = to that planned for the event
• three high intensity days - zone 4
• one or two interval workout days which are counted as one of the three zone 4 days. For example:
  • warm up - zone 1
  • 20 min - zone 3
  • 5 min - zone 4
  • 7 intervals - hit 90% max, recover to 60 - 65% max
  • 5 min - zone 4
  • 20 min - zone 3
  • warm down - zone 1
• the sixth and seventh days of the week can be rest days off the bike or slow recovery rides at zone 1 or 2 exertion to stretch out your muscles.

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 speed of is then the govener (sic)."

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:

• Should I consider my Max HR as 185? or what should it be?
• As it is quite far from my theoretical Max HR, what does it mean: Am I in good shape? Not in good shape? Means nothing (just genetic)?

A. Here are a few thoughts-

• Maximum heart rate is very individual and all the rules to "calculate" MHR are just approximations to get you into the ballpark for you. Your maximum heart rate is what you have actually measured for yourself (185 for you).
• Maximum heart rate has nothing to do with what shape you are in. And yes, it is probably related more to your inherited physiology (genetics) - assuming you are healthy - than anything else.
• Use your maximum heart rate (and %'s thereof - training zones) as general training guidelines, not absolutes. Which means a difference of MHR of 180 versus 185, really is not that big a deal. This is not engineering (which is precise and reproducible day to day), but a biologic system which can vary from day to day. That's why perceived effort - which takes into account day to day variation in your biology - as a training tool makes more sense to me.

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.


Cycling Performance Tips