Perceived effort: The new scientific measure?

By Melanie McQuaid

Feb. 21, 2007 -- I was lucky enough to take part in some physiological testing during my last training camp in California. As part of the Floyd Landis 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. At this time, it is important for me to see my yearly starting point. 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 during this year's test. In addition to watts, heart rate and lactate values, Alan measured 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:

0 Nothing at all
0.5 Extremely easy
1.0 Very easy
2.0 Easy
3.0 Moderate
4.0 Somewhat hard
5.0 Hard
6.0
7.0 Very hard
8.0
9.0
10.0 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, percentage of 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 increased 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, however, as male cyclists had closer 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 useful metric for athletes, especially those new to 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 -- not to try to hold onto a number.Although I measure a performance objectively using heart-rate and power data, I choose to ignore my measuring devices while I am competing. I perform based on feel and measure the actual performance using numbers. If you try to perform using only numbers on race day 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. 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.

Based in Victoria, Canada, Melanie McQuaid is a three-time defending XTERRA world champion. For more information about McQuaid, please visit www.racergirl.com.