We all know what lactate is – it causes the burn in our legs.
However, physiologists differ in what they call it, how to measure it and how to use it: lactate threshold, anaerobic threshold, ventilatory threshold, onset of blood lactic acid (OBLA), etc.
You don’t need a Ph.D. to understand it all, nor do you need to be confused. Do what I do and use Rate of Perceived Exertion (RPE), which is much simpler and just as useful as a heart rate monitor.
Here’s a quick personal example
I time-trialed Flagstaff Road yesterday, a classic Boulder, Colorado, climb that was used in the USA Pro Challenge when it finished in Boulder several years ago. We haven’t had snow recently, and it was in the 60s, so it was a glorious day.
I didn’t use a heart rate monitor, much less a power meter. I just paid attention to how my body felt overall: breathing, muscle strain, the burn, etc. If I tried to go a little harder, I started gasping for air and my legs screamed — too fast. If I backed off my legs weren’t talking to me and I could talk — too slow. In between those was my sustainable time trial pace — just right. I’m very pleased with my time for an early season climb.
When I repeat the climb later this spring to gauge the improvement in my fitness I’ll listen to my body the same way, paying attention to breathing, muscle strain, the burn, etc. If my time is faster, then I’m getting fitter. I don’t need to know what my heart rate was yesterday, or how many watts I was producing, or what those numbers are on the climb later this spring.
Lab tests have shown that perceived exertion is as good an indicator as heart rate of how hard a rider is working. My experience as a coach supports this. Several years ago I coached two riders training for the Race Across America. After building big endurance bases, each rider did intensity training to improve his cruising speed and climbing. One rider used a heart rate monitor and the other used RPE. They finished fourth and fifth, just a few hours apart.
RPE’s many advantages
Rate of Perceived Exertion has several advantages over a heart monitor. RPE is:
- Free. You don’t have to buy any equipment.
- Simple. You don’t have to interpret numbers and remember training zones.
- Faster to respond. When you change your level of effort, particularly when suddenly going much harder, it takes a few minutes for your heart rate to increase all the way to the new level; however, you feel the new intensity instantly.
- May be more accurate. You are gauging how hard your muscles are working rather than how fast your heart is beating, which can be influenced by other factors such as nerves, heat, dehydration, etc.
- Pacing. With prolonged exercise your heart rate may increase even though your muscles aren’t working any harder. This is known as cardiovascular drift. Because your heart rate has gone up you may think you should slow down. With RPE you’ll continue to ride at the same level of effort.
- More reliable. Feedback is not subject to equipment blips or failures.
- Safer and more fun. You can look at the road and scenery instead of figures on a gadget.
RPE measured on a scale of 0 to 10
Training by perceived exertion usually uses a 0-to-10 scale. Zero is no exertion and 10 is a maximal sprint for just a few seconds. I have my own way of gauging intensity specifically for cyclists and give the RPE equivalents. Because power production is a continuum, the different paces and RPEs blend into each other.
Digestion pace: How you ride after a big breakfast or lunch, an RPE of 1-2. This is the pace for active recovery rides.
Conversation pace: You can carry on a conversation in full sentences, an RPE of 2-3. This pace builds endurance and trains the aerobic system to burn fat more efficiently. Even lean riders have enough fat to help fuel a longer ride, so training this system is important.
Hill climbing and headwind pace: You’re on a long, steady grade or riding into sustained wind. You’re working hard enough that you can’t whistle but can still talk in short sentences, an RPE of 3-4. At this pace you’re improving your cruising speed and training the aerobic system to burn glycogen.
Power pace: You are riding up a relatively short climb and or into a headwind. You can talk in short phrases but not short sentences. An RPE of 4-5
Sub-barf pace: Making a hard, sustained effort, an RPE of 5-6. This is the pace for a 20- to 40-km time trial or racing up a hill. You’re riding anaerobically to train the lactate system to burn glycogen without enough oxygen and producing lactic acid — we all know that feeling.
Eyeballs-out pace: This is the classic hammering pace, a hard effort for a few minutes with eyes bugging out, an RPE of 6-7.
Ouch pace: Sprinting at an RPE of 8 or more for a short time.
Yesterday for me was sub-barf. I never go eyeballs out on a climb like that. Even though I don’t race, I throw in a few sprints into an endurance ride. Sprinting improves neuromuscular coordination, training your individual muscle fibers to fire simultaneously. It’s like dialing in the timing on your car engine.
During my multi-hour XC ski races this winter, I was careful to stay at my conversation and hill-climbing paces so I didn’t run out of gas. At my last race in Crested Butte, the collegiate teams raced sub-barf until the last kilometer. The podium finishers crossed the line, fell down and started to puke!
One final note: I’m writing a new eArticle for RBR tentatively titled: Intensity Trainingfor Cyclists: Using Perceived Exertion, a Heart Rate Monitor or a Power Meter to Maximize Training Effectiveness. Look for it soon. It will show you how to use RPE effectively improve your training!
Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written nearly 30 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John's full bio.