Why You Should Train With Percieved Effort

A long time ago (2007) I went down to take part in some physiological testing during a training camp in Temecula, California.  As part of Powertap training camp, Alan Lim conducted step tests to determine lactate threshold for all the campers.  I normally do four of these tests per year, with one in the early stages of my base preparation phase for the season.  In the early season, it is important for me to see my yearly starting point.  It is encouraging when my January results reflect previous results for late in the previous season, which is an indication that overall my form from year to year is improving, but that is not always the case.  I always look at test results as a relative measure rather than an absolute indicator.  Just as you can have good and bad days racing, so too can your tests vary according to how you feel.  Never beat yourself up about test results… there is something called competition that truly measures individual ability.  Only races will really indicate your true athletic potential.

Alan measured an interesting marker that during this year’s test.  In addition to watts, heart rate and lactate values, Alan measured our perceived effort and graphed all of the numbers together.  Perceived effort was first quantified by a man named Gunnar Borg.  He created a 15 point 6-20 scale to produce estimates of exertion.  This scale has also been adapted to the CR10 Scale as follows:


  1. Nothing at all
  2. Extremely easy
  3. Very easy
  4. Easy
  5. Moderate
  6. Somewhat hard
  7. Hard
  8. Very hard
  9. Extremely Hard (maximal)

California researchers studied the Borg scale to establish whether this scale was valid as a measure of exercise intensity.  By comparing RPE scores with physiological data (heart rate, lactate concentration, % VO2 max, ventilation and respiratory rates) they were able to determine whether perceived exertion was comparable with measured exertion.

In general, their findings were that there is a definite correlation between perceived effort and actual exertion.  There was a linear correlation between heart rate and VO2 as exercise intensity increases and a high correlation between other measures such as lactate values. In general, the more highly trained an athlete, the stronger the correlation. This makes sense, as a highly trained athlete would be more in tune with his or her limits.  There were some inconsistencies as male cyclists had higher correlation than females or athletes from other sports.  Therefore, some variables will affect how closely perceived effort will follow a lactate curve.

This does mean, however, that training by “feel” can be a strong metric for athletes, especially those embarking on their career in triathlon.  Many of us had a beginning where heart rate monitors and power measuring devices were not part of our programs so we learned to train “hard” and “easy”.  With so many useful devices, some athletes can become a slave to numbers and forget that the point is to push yourself to your “limits” and not to try to hold onto a number.

Although I will measure a performance objectively using heart rate and power data, I choose to ignore any measuring devices while I am competing.  When I won Ironman 70.3 Oceanside in 2012, every single one of my devices was not working for some reason or another.  I raced without even seeing my cadence and had at that point my best career performance at the half Ironman distance.  I have tried a number of strategies but racing based on “feel” while measureing the actual performance using numbers for later consideration seems to be the best.  If you try to perform using “numbers” you may over or underestimate your potential on a given day.  Better to just toe the start line with a race strategy and dig as deep as you can.

So try to gauge your RPE the next time you do a lactate or VO2 max test.  You may be amazed at how well you can estimate the effort corresponding to your lactate threshold.  It is that “sort of hard” zone.  Scientific stuff.




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