bike75.gif (2872 bytes)


  Last updated: 1/16/2016


How hard am I working? Am I pushing myself and getting the maximum from my training efforts? These are common questions for those of us focused on a high quality workout. Although Heart Rate Monitors are touted as THE only way to know the exact intensity level of your cardiovascular workout, there is a cheaper, easier (and perhaps better) alternative - the Rating of Perceived Exertion (RPE or PE) scale {below} proposed by G. A. Borg in 1982 (Med Sci in Sports Exer. 14(5):377-81, 1982).

Perceived exertion was the approach used by Lance Armstrong in his 55-km (34-mile) time trial victory in his 6th Tour de France. The following is from an interview with Phil Liggett and Paul Sherwen. "I didn't have a speedometer. I said I'm not looking at speed, I'm not looking at cadence. I'm just going to ride like I feel."

It worked. He won the stage convincingly, taking 61 seconds out of time-trial rival Jan Ullrich. "Going naked" in a TT seems an unusual strategy for Armstrong who, prompted by coach Chris Carmichael, is an extremely scientific cyclist. Lance uses a watts meter on most rides and sends Chris the files to download and analyze for planning subsequent workouts. Lance could have ridden the TT with a watts meter to monitor intensity and avoid crossing his red line. Yet the only feedback he used was what his body was telling him. Like many experienced riders against the clock, he has a keen sense of pace. He has learned to tread the border between going at a semi-comfortable pace (thus losing time) and going too hard early (thus slowing dramatically in the final kilometers).

And here's another I found in "In a recent interview with VeloNews, 2004 Paris-Roubaix winner Magnus Backstedt commented on how his training changed after several years of poor results. "I got back to what I did when I started racing", said the 30-year-old Swede. "[I had been] doing all kinds of controlled training, hitting thresholds, intervals, all that. Instead, I went back to what my body told me. I took every single piece of equipment off my bike. At the end of the day, despite what technology tells you, if it's not right, it's not right. It's been fine ever since."

Backstedt's comments have provoked lively exchanges on internet discussion groups devoted to training. Some applaud his return to more "natural" workouts. Others deplore his flight from analysis and scientific training with watts meters and heart monitors. Which approach works best? We like the way Allen Lim, Ph.D., coaches his riders. In his ground-breaking doctoral work at the University of Colorado, Lim analyzed data from power meters used by pro riders in races and training. You'd think Lim would advocate scientific training. He does, but recommends a middle ground: training by feel and then analyzing the results by scientific means.

Structured training plans are important to help you meet your cycling goals. But as Lim and Backstedt point out, you need to be flexible. If your training plan calls for hard intervals, climbing or long distance on a certain day and your body isn't cooperating, it's crucial to recognize that you're not ready for more work. Then apply a combination of less strenuous workouts and more rest instead of blindly soldiering on and digging yourself into an even deeper hole.

The key to improving is using a combination of perceived exertion and interval training. For longer than 30 seconds, your maximum sustainable pace will be your lactate threshold (LT) which is approximately 90% of your maximum heart rate. You could use a HRM to pinpoint the highest heart rate you can maintain for 30-60 minutes. But you can also ride without a heart monitor (or power meter) and listen to you body, constantly monitoring your sense of perceived exertion. To take this approach, learn to pay attention to your lungs and legs.


Do all those gadgets (HR monitor, power meter) and laboratory tests (lactate levels) give you a training edge compared to the use of perceived exertion? It's not clear - and when you look at their costs and the distraction of using them, as well as the potential to injure yourself if you are mindlessly training to the numbers, they may actually keep you from maximum improvement. We know that improvement requires stressing the muscles to the point that actual structural injury occurs. Repair of the injury includes adaptation which leads to better performance. This is the logic (and science) behind interval training.

Individual monitors don't provide one critical bit of information – are we pushing at our personal physiologic peak – adding that critical extra amount of training stress? Or are we merely chasing a number.

A comment from my page on pacing is as relevant to training to your max using a HR monitor or power meter linked to an interval strategy as it is to overall race performance: "The influence of clock watching (sic - you c an insert HR or watts here) on endurance performance is two-sided. The same time goal that enhances performance when it is perceived as a target constrains performance when it is perceived as a limit. The potential for time standards to become performance limiters is most apparent at the elite level of endurance sports."

How do you identify the level of activity that stresses your muscles and CV system to maximize improvement? It needs to be based on how you feel, not a HR or watt meter number. And that feeling of maximum tolerable level exertion is your perceived level of exertion. I know we all have had that day when our heart rate and level of performance seem to be out of sync – a "bad day". On those days we should listen to our body, not to our gadget. Chasing a number risks injury. Likewise on a good day, we may reach our HR goal yet feel we still have more we could do. On these days we should again use perceived exertion rather than a HR number for that day's interval goal.

Perceived exertion is our conscious awareness of the central governor, the integration of multiple physiologic inputs which help to protect us from injury by setting an upper limit on our level of exertion. That tight rope of enough exertion to provide maximal stress without too much which increases the odds of injury. And your central governor is the most sensitive measure integrating all the internal measures that are your body's monitors (your dash board) of how the "engine" is functioning. It is multiple inputs which include such things as "..lactate levels, VO2max, heart rate, heart-rate variability, rapid morning heart rate, recovery heart rate, hormone levels (cortisol, testosterone, etc.), red cell counts (hemoglobin, hematocrit, red cell indices), immunity (white blood cells, interleukins, inflammation), muscle damage (creatine kinase, oxidative stress), blood pressure, and much more."

As Dr. Mirkin put it: "....these devices cannot tell you whether you are exercising intensely enough to gain your maximum improvement in ability to take in and use oxygen or to damage your muscles enough for maximum strength gain. Only your brain can tell you whether you are at your maximum, if you need to take off because you are about to injure yourself, or when you need to slow down because you are exhausted. Fitness gadgets can help to motivate you and can be fun to use, but do not count on them to tell you how intensely you should exercise or when you are at the edge of an injury."

I could not find the original article he referenced but I'll quote: " from Deakin University in Australia reviewed 56 studies that compared the way that electronic devices and your brain tell you when to slow down or stop exercising (Br J Sports Med, September 29, 2015). Half of these studies showed that the brain and sophisticated machines were equally effective in telling you that you are training too intensely and need to reduce your training. The other half of the studies showed that 85 percent of the time, the brain was a better gauge of over-training than sophisticated machines."

My bottom line? Although monitors are a great tool, and do help keep us engaged with our training program, if I had to pick, my preferred approach would be based on a program of structured stress (intervals) using perceived exertion as my measure of maximal stress rather than a single number such as heart rate or power output.


The RPE scale ranges from 6 to 20*, and includes a literal description for each level of exercise intensity. It was designed so adding a 0 to the level of exertion would give a rough estimate of your heart rate i.e. if you were resting (a 6 on the scale) your heart rate would be in the neighborhood of 60. Although RPE isn't accurate enough for detailed physiologic studies, research has demonstrated an amazingly high correlation for any individual from day to day. In other words if you felt you were exercising at a 13 (somewhat hard) on two different days, and checked your heart rate, it would be quite similar.

How can you use the RPE scale? First familiarize yourself with the levels. Then, using a treadmill or wind trainer, rate your own level of exertion BEFORE you check your pulse rate. With a little practice you will find that you will be amazingly accurate in predicting your heart rate. At that point you can use your own RPE instead of a heart rate monitor to monitor the intensity of the day’s workout.

In addition,

RPE can change as fitness improves and with factors such as hydration, carbohydrate status, and ambient temperature. So recalibrate your own RPE scale regularly during the season if you are using this tool in your training. A heart rate monitor or a watts meter are important tools. But when it matters most, your carefully honed self-perceived exertion level is still the best monitor ever created.

It has been shown that caffeine decreases perceived effort and muscle discomfort with aerobic activity (cycling). Interestingly, this effect was not the case with the use of aspirin as comparison.



Question: I want to improve my power at lactate threshold (LT) so I can excel in time trials and on long climbs. But I don't know how hard to ride during LT training. Lab tests are expensive, I'm told that heart rate is unreliable and I don't have a watts meter. Is there a simple method for nailing LT intensity without all the black magic?

Answer: PE can be used in 2 ways. First is with intervals. Here you want to be a 10 for 30 to 40 seconds. That will maximize your effort and provide the interval training benefits.

The other is to use PE to ride at your lactate threshold for longer periods.The following comment is quoted from as it nicely summarizes the concept.

LT can be gauged by wattage, lactate accumulation, heart rate or perceived exertion. The first requires a relatively expensive power meter as well as a lab test to find your wattage at LT. Actually measuring lactate means periodic blood draws -- not too practical while you're riding the road. And heart rate can vary for a given power output due to hydration status, environmental conditions and other factors.

That leaves your personal rating of perceived exertion (RPE). In other words, how hard you feel like you're riding. In the old days, everyone trained with RPE. Before heart monitors there was no other way. The good news is that research shows RPE is an effective way to determine intensity.

Allen Lim did ground-breaking research on cycling power while working on his Ph.D. in exercise physiology at the University of Colorado. In an e-mail he wrote:"Training prescriptions don't need to be overly complicated. If athletes are in tune with themselves and quite experienced at perceiving effort, then what they perceive as hard can be used consistently as a reference point for training-induced adaptations and for determining training pace."

So, if your workout calls for a 20-minute effort at close to your LT, it's fine to forget the technology and simply ride at an intensity that feels hard. You'll be close to your lab determined ideal intensity.

How hard is hard? Think of effort on a scale of 1 (lying on the couch) to 10 (riding flat-out and suffering). On this simplified RPE scale, LT intensity is between 8 and 9. This is the point at which breathing is at the breakpoint between hard but steady and labored with gasping. Another way to find it: Increase intensity until you begin to gasp, then back off a notch.

Questions on content or suggestions to improve this page are appreciated.

Cycling Performance Tips
Home | Table of Contents | Local Services/Information