Heart Monitor? Power Meter? Don’t Forget the Brain! – Perceived Exertion as a Measure of Effort

Bike racers train to gain physiological adaptations that will allow them to ride faster, farther or more aggressively. The response to training depends on the details of the training and on the condition of the rider beforehand, but not on whether or how the training stimulus is monitored. The legs don’t know if a rider is making a particular effort under direction of an external device like a heart rate monitor or a power meter, because of a chasing dog, or just because the effort feels right. The changes that will occur in the body after a training session depend on which muscle fibers contract, how many times and how hard. They depend indirectly on the power output, but not on whether the rider knows that power output. Heart rate monitors and power meters can help a rider to judge effort, but a rider who learns to make the same effort will get the same response, without use of a monitor.

Each individual fiber within a muscle experiences adaptations that are dependent on the training experience of that one fiber. A fiber that is challenged in such a way that it does a great deal of glycolysis (sugar-splitting, lactate producing, anaerobic metabolism) will develop more of the enzymes that support glycolysis, but very little of the mitochondrial mass or enzymes that are essential to fat utilization or aerobic metabolism. A fiber that is challenged aerobically in training will end up with enhanced aerobic capacity. A fiber that does little work in training will have an opportunity to replenish energy supplies and make repairs, but will experience no other changes or may detrain if it was previously trained.

A single muscle contains thousands of muscle fibers, each of which can participate or not participate in any given contraction of the entire muscle. Which fibers contract depends on the intensity (force) and frequency of the contraction, and the training and fatigue states of the individual fibers. That means that two periods of exercise with the exact same power output from a given muscle can rely on many different combinations of fibers within that muscle and result in different training effects. When the most readily activated fibers are fatigued, less often activated fibers get called up. No external intensity measure by itself can effectively describe these changes, but comparison of perceived exertion and heart rate or power can give some insight.

Measuring Effort

Over the years, a variety of methods have been used to monitor training effort. Up until the mid-1980s, training stimulus was measured by perceived effort, training volume, average speed and gears used. Starting in the mid-1980s, heart rate monitors became the majority choice. In the 1990s blood lactate-measuring devices had a brief ascendancy. Since 2000 or so, power-measuring devices have become available and have gained popularity. Each time a new device has been introduced, a group of early adopter, proselytizers has formed to sing the praises of the new device and to tell the world that if they are not using the new gizmo, they won’t be winning or at least not for long.

When I began coaching professionally in 1994, light wheels had 28 spokes, fancy bikes had seven gears in back, steel was real, and heart rate monitors were the rage. Riders who bought monitors thought themselves on the brink of elite success. Serious racers were testing their Conconi thresholds, establishing training zones, and riding in them confident that they were doing exactly the right thing to make themselves as strong as possible.

Today light wheels have half as many spokes as they did in 1994; cassettes have ten or eleven cogs; steel has been replaced by carbon fiber; and power meters are the rage. Otherwise, today is very similar to 1994. Lots of people have meters and record their rides. Many riders with no background in sports science are suddenly experts, and riders are once again chasing the Holy Grail of a non-thinking, mechanically designed training plan that guarantees optimal results. Overall, the average fitness of racers isn’t changing much as a result of ownership of the new devices.

Prescribing and Monitoring Training

In 1994, my partners and I started a business of taking heart rate testing data and other personal information, and turning it into training zones and plans. Our clients did pretty well. As far as I can remember, we only had one visible detractor: Roger Marquis, a long-time category 1 rider, professional MTB racer and successful collegiate coach said that we were selling snake oil; that training strictly in a narrow heart rate zone was not the path to cycling salvation. He went on about knowing what your body needed and was ready for, independent of any monitoring device. Meanwhile, we believed in what we were doing, and many of our clients had excellent results including wins, upgrades and medals from District and National Championships, so we felt justified and perhaps smug in our success. Our business grew. We thought of Roger as somewhere between an annoyance and a threat since he was trying to undermine our basic business, but we basically ignored him and hoped that everyone else would, too.

Over the following decade we diversified our offerings and continued to refine our programs, modifying and adding details to the instructions based on rider feedback. Overall our clients continued to improve, but some did better than others and we wanted to know why. We accumulated evidence and encouraged more of the behavior that seemed to be most beneficial.

The most obvious distinction was that the successful riders put in their time. Each rider seemed to have a threshold volume required to achieve road-racing fitness. Some lower category riders could fly on eight hours per week, while most did well around 10 and a few seem to need 12 or more. (Side note: The volume thresholds have increased by at least two hours as fields have grown and training knowledge has improved in the more populous districts. One can still be a fast category four on eight hours per week, but no longer a winner, at least not in the tougher districts. Another note: riders most interested in criterium racing can often get away with much less volume if they have good skills).

Generally riders who put in more hours got faster, so we encouraged our riders to find the time to train more. For most but not all riders, increasing training time translated to improved fitness and improved competitive results.

More Hours Are Not Enough

There are many factors other than the training plan and how one follows it that help or hurt performance. That’s why a training plan from a magazine, a book or even a web based, interactive training service, can’t substitute for an actual coach. Coaches provide objective observation and expert guidance to help riders identify and correct problems of on- or off-bike nutrition, excessive energy expenditure in races, body weight, equipment choices, tactics and numerous other issues that can impair performance. Generally the more riders are able to absorb and follow the guidance of a good coach, the better they do. Still, even with good advice, proven training zones, proven exercises, good nutrition, and adequate training time, some of our riders turned pro or won nationals while others remained stuck in the 3s or 4s. What was the key to this puzzle?

Over the years I accumulated enough experience with many hundreds of more and less successful riders to be able to identify another element of the pattern. Wenzel Coaching exercises generally include a “plan B” option for bad days. The riders who seemed mired in the 4s and 3s have been the ones most likely to say, “hey coach, I did all the training” or “I stayed in the zone the whole time”, wanting a pat on the back for training so diligently. The ones who win and move up and win again are the ones who really follow the plan, including the “plan B” instructions. The successful riders occasionally admit that they weren’t feeling great so they did the easier version of the plan for the day. In other words, no matter how good the program, no matter how good the measurement system, success as a bike racer seems to require becoming sensitive to one’s own state of fatigue and recovery.

Roger Marquis Was Right

A heart rate monitor or power meter can help one identify good and bad days and what particular rides should feel like, but eventually one must develop one’s own judgment and trust it rather than blindly stick to the numbers. Most riders with a monitor and good guidance can develop the necessary sense of effort and fatigue in a few years, after which they can just use the monitor periodically to check their intuition. A few riders never develop the sense and need the monitors indefinitely. The meters don’t lie, but they also miss an important part of the story. I’m not saying an aspiring champion should ignore the heart rate monitor or power meter. One or the other of them is close to essential for novice and even moderately experienced racers.

The measurement device allows a coach and rider to be sure they are speaking the same language; to be sure they mean the same thing by “easy”, “moderate” or “hard”. Eventually however one needs to learn to feel one’s own readiness and need for harder or easier training. The heart rate monitor or power meter as a training tool can help a rider to learn what a recovery ride, aerobic ride or hard ride should feel like. By comparing heart rate or power with perceived effort from day to day, one can learn to identify fatigue that may not be obvious otherwise.

Other than simply taking the time to do the necessary training, the abilities to identify fatigue and allow recovery when needed are the main distinctions I have found between more and less successful riders. Monitors are invaluable for developing these abilities. Reaching one’s potential without some sort of monitor is much harder than with. Still, the meters are just two tools among many. Using them and ignoring other assets and information sources will leave one about where one would be without the meters.

Is the Heart Rate Monitor Era Over?

I recently read an article in which another coach argued here in ROAD magazine that the heart rate monitor as a training tool is dead. I supervise clients by their choice of heart rate or power and clients in both groups are experiencing plenty of successes. In the few days after I read of the death of heart rate monitor training, I got a call from a client who had just won two medals at Masters Nationals, and an email from a client who had just won his 9th event and gotten his 12th podium spot racing his debut season in Europe. Neither of these riders uses a power meter as yet. In the past few months, riders not using power meters have earned numerous podium spots in local and regional events. Clients using power are also making progress and finding success. There is no clear line between the progress made with and without the power meter. (As a note or disclaimer, unlike some coaches, I make the same amount of money whether my client uses power or heart rate to guide their training).

Is Power Training the Path to Cycling Salvation?

Purchasing a power meter, setting up the zones and training in them is no more a guarantee of cycling success than training by heart rate or lactate ever was. Blindly training by power to the exclusion of common sense can even destroy a rider. An ex-client of mine made the error of training in the power zones established on one power-measurement device while riding a different unit of the same brand. Unfortunately the second unit read roughly 10% lower than the first, so the whole time he used the second unit he forced himself to train roughly 10% harder than the zones he had so carefully established. He noted that he was getting tired more often, but didn’t change his training as a result, so he ended up overtrained and missed much of that season.

The Ultimate Monitor

The human body is not a machine to be tuned mechanically or forced to respond by training it to a certain zone. There are literally dozens of factors that affect what training or recovery activity is appropriate on any given day. Until someone invents a monitor that can simultaneously sense a rider’s emotional state, sleep patterns, hydration, heart rate, lactate levels, core temperature, and glycogen supply plus external temperature and humidity and all the other relevant factors, we will not be able to achieve cycling success simply by following a mechanical plan. Actually the monitor that simultaneously tracks all those factors already does exist and each rider has one: The rider’s brain integrates all the necessary inputs and, if trained appropriately, will tell the rider precisely what to do on a given day and how well the training is working.

This article by Scott Saifer, M.S. first appeared in ROAD Magazine in September of 2007.