ASSESSING PACE AND INTENSITY
There are A TON of metrics used to assess intensity and pace in endurance sports – heart rate (HR), rate of perceived exertion (RPE), lactate threshold (LT), revolutions per minute (RPM), the list goes on. Do an internet search for the best way to measure intensity or gauge pace and you’re likely to find many different answers. While different exercise modalities tend to favor one benchmark over another (i.e., FTP for cycling), it is important to realize that singular benchmarks are limited in value .
BODY WEIGHT ANALOGY
Let’s look at it from the perspective of weight loss. Most people associate and measure weight loss by a body weight scale – a singular method. While this method does show how much absolute weight is lost, it does not give any indication to how body composition changed.
For example, you might have gained 5 lbs but when you do a body composition assessment, you found that you reduced your body fat by 4%. The resulting gain in weight is then most likely due to an increase in lean muscle mass, not fat. Since a pound of muscle is approximately half the size of a pound of fat, it is also likely that you look much better at this weight than you would if the 5 lb weight gain was all fat.
OK, back to the point of this post.
CORRELATIONS GIVE THE WHOLE PICTURE
Like body weight, intensity benchmarks such as power or heart rate mean little in isolation. They must be correlated with other intensity benchmarks to have real value.
For example, let’s say that through training, it is determined a triathlete has a Functional Threshold Power (FTP) of 250 watts. Therefore in the next triathlon where the bike segment lasts approximately an hour, the triathlete aims to target and sustain 250 watts. However on race day, the triathlete is having an “off day” and struggles to maintain 250 watts. In addition to their Rate of Perceived Exertion (RPE) being higher than normal at a set wattage, their heart rate is approximately 10 beats lower than normal, suggesting fatigue. If the triathlete didn’t correlate their heart rate and RPE with the FTP prescription of 250 watts, they would likely try to push through the bike segment at a intensity level that’s too high and would likely “hit the wall.”
Training benchmarks and metrics are great and necessary however they must be correlated to have the greatest value. Training benchmarks used in isolation not only have limited practicality but can put an athlete in serious difficulty or danger if strictly adhered to in isolation.