RPE—Trust Your Gut

Over the past ten years or so, training instruments such as heart monitors and power meters have been key players in the popularization of science-based training.   Thanks to these products, more people are more educated about how to train methodically than ever before.   These items have also become very trendy.    Naturally, the more advanced an instrument is, the more trendy it seems to be.   You can spend as much as you dare on these little boxes that can feed you more information than an F-18 pilot receives in flight, but is this money well spent?  

Simply owning expensive power meters, heart rate monitors or bar-mounted GPS units won't make you a faster cyclist.   Most of these units offer far more features than are necessary for training.   These gadgets can become cumbersome to use and the excess information can distract you from what's important—working hard when you're rested and recovering when you're tired.   Add to this the fact that these are complex machines created by humans, which by nature makes them imperfect.   I like to joke that my aging heart monitor likes to take Sundays off--it will function just fine all week until Sunday, when it gives obviously low readings, if any at all.

Heart Rate Monitors (HRM's) were revolutionary when they first appeared on the market and over the past ten years, the methods for using them effectively have been refined significantly—for example, training zones are now based on aerobic threshold rather than max heart rate.   Simple HRM's have become relatively inexpensive and are valuable for helping athletes understand and assess their bodies' response to both immediate and cumulative workloads, rest, heat, fatigue and anxiety.   HRM's are valuable for monitoring one's effort over work intervals of one minute or more.

Heart monitors have a few significant shortcomings, however.   They aren't useful for gauging efforts of less than about 60 seconds, such as in sprint workouts because of the delayed heart response to changes in exertion.   Heart rate is also drastically affected by anxiety, making for unusually high heart rates during times of heightened arousal, such as during races.   This can make it difficult to pace one's efforts in a race—especially at the start or during a crucial moment in the race.   Heart rate is drastically increased by heat and decreased in cool weather.   Heart rate is also altered by fatigue, so near the end of a stage race or on a second or third consecutive day of heavy workload, the training zone you expect to work within may not be achievable.   Finally, your HRM itself may simply be inaccurate.   As mentioned before, mine only functions about 6 days out of the week.   On other days, I'm not certain but am suspicious of its inaccuracy.   Age and the corrosion, wear and tear that HRM's are subject to will generally bring about their demise in only a few years, requiring you to reinvest, regardless of what you paid for it.

The new wave of training instruments is power meters.   These ingenious little machines attempt to measure the energy you apply to the pedals and nothing else.   This factors out the myriad of variables that affect your speed, such as wind, incline, surface quality, temperature and your cool new sunglasses (Yes, sunglasses affect your speed.   Just ask Mario Cipollini.)   Notice that I used the verb “attempt” and not just “measure”.   Not all power meters truly measure power output.   Some attempt to “calculate” a “virtual” power.   This is apparently accomplished using your weight and speed, but can't remove the variables of wind and incline.   Some products have dubious means by which they measure your output that leave considerable room for user error and can even lose accuracy with certain gear combinations or leg strength discrepancies (being dominant in your left or right leg).   There are power meters that are very accurate and reliable, but they are still very expensive.   Also, they either restrict the user to a certain rear wheel or are troublesome to move from one bike to another, such as if you have a separate time trial bike and road bike.  

Power meters are excellent tools for measuring output during very short, intense efforts as well as extended efforts.   They are also very helpful for pacing oneself in a time trial to avoid overexerting in the first few minutes.   Training by power meter uses zones based on aerobic threshold, just like HR training, exchanging your heart rate at threshold for wattage at threshold.   Of course, just as your heart rate at threshold can vary with temperature and fatigue, so can your power at threshold.   This means that your training zones can be just as transient depending on workload and weather.

There is an answer, however, to the question of how to measure exertion while accounting for all variables and it interchanges easily with all bikes and any wheelset.   It's also the least expensive option of the lot.   It's called the human brain.   Granted, some work better than others and they can be moody, but no other instrument is as adapted to accounting for multiple small variables as your mind.   It has direct communication with your body and gets constant reports on the stresses you're undergoing and the efforts you're exerting.   It recognizes wind, down to individual gusts and it's direction, hills and road surfaces.   The problem is learning to use it.   It takes practice—trial and error—to determine how long you can maintain a particular effort before losing power.   This is a skill that can be refined, however.

Well-known coach Allen Lim completed his Doctoral thesis studying the accuracy of athletes' ratings of perceived exertion (RPE).   What he found was that trained athletes were impressively accurate at estimating their training zone at a given effort.   Further proof of the effectiveness of RPE   is the example of Lance Armstrong winning a time trial in the tour without a power meter or heart monitor.   He just knew how hard he could ride for the distance he had to go.   How do you hone this skill yourself?   Simple—just listen to your body and stop staring at the screen on your handlebars.   It's not bad practice to have the data available and to glance at your heart rate or power occasionally to help learn what it feels like to be at each training zone, but don't become dependent on it and don't agonize over not being able to reach the zone you were planning to train in on that particular workout.   If you felt the intensity you were aspiring to, that's probably where that training zone is for you on that day.   A heart monitor can be helpful for indicating to you when you're too tired for a given workout and need to pack it in and take a nap, but chances are that you will also feel sensations from your body that tell you the same thing.   A power meter can be better than perception for pacing yourself in the first ten minutes of a time trial, when your arousal can fool you into overexerting, but with practice, this, like any bad habit, can be managed.

Training is partly a science and partly an art form.   The science is helpful and brings an element of precision to the table that wouldn't otherwise exist, but sometimes the number of variables exceeds the limits of current science.   This is when the athlete must know to ignore all of the numbers in front of them and trust their gut.   Listen to your own breathing.   Pay attention to the sensations in your legs.   Examine your mental state—are you nervous…excited…focused…angry…euphoric?   Are you under-aroused?   This will play a role in your perceived exertion, altering your internal instruments.   Sometimes it's helpful; sometimes it's detrimental.   The less dependent you are on your HRM or PM, the better you'll manage when the battery dies or when the data belies your situation.