Measuring Intensity in Endurance Training

Having discussed the importance of knowing the seven different zones for endurance development, let us now turn our attention to ways we can measure intensity in endurance sports. There are a number of ways we can measure intensity with some requiring equipment, some requiring considerable skill and experience, and other methods requiring basic skills and knowledge.


When I first became involved seriously with running in the early 70’s, pace was everything. Four-, five-, six- or seven-minute mile pace were the gold standards used. These days we use time/400m run or time/100m swim and base these off goal 10k run or 1500m swim pace or current best 5000m run or 1500m swim times. The problem is that the feedback doesn’t come until you’ve finished the distance and looked at the time. In cycling the feedback can be instant if you have a bike computer but is affected by wind direction, hills, or where you are in the bunch. However, for the experienced aging endurance athlete, pace is great for swim and run workouts and tables are found in the endurance literature to help you. I personally use tables found in Joe Friel’s excellent triathlon training book called The Triathletes Training Bible. The pacing method takes experience, a strong awareness of your body and how it feels in the various heart rate training zones, and a wristwatch, bike computer or pace clock.

Rating of Perceived Exertion (RPE)

The experienced aging athlete has a well-developed ability to know how hard they are exercising based on things such as breathing rate and depth, sweat rate, muscle sensations, and overall body sensations. This perceived exertion requires no equipment just a sense of body awareness. Two scales exist for the RPE scale that is sometimes called the Borg Scale after the person that developed it. The original 6-20 scale was developed to represent 60-200 heart beats per minute in younger university students. However, aging people can still use it although a newer 1-10 scale has been developed. 6 on the old scale (1on the new scale) represents rest while 20 (10 on the new scale) represents very, very hard intensity.

Old 6-20 Scale New 1-10 Scale
Rating Description HR Zone Rating Description HR Zone
6 No exertion 1 1 Very, very light 1
7 Extremely light 1 2 Very light 1
8 1 3 Fairly light 2
9 Very light 2 4 Light 3
10 2 5 Somewhat hard 3
11 Light 3 6 Moderately hard 4
12 3 7 Hard 5
13 Somewhat hard 4 8 Very hard 6
14 4 9 Very, very hard 6
15 Hard 5 10 Extremely hard 7
16 5
17 Very hard 6
18 6
19 Extremely hard 6
20 Maximal exertion 7

The RPE scale is commonly used for novice or recreational athletes, aging people getting into exercise for the first time, or people rehabilitating from a medical condition.


Sport scientists use measures of power when prescribing from or describing test results. We generally talk in terms of units called watts but to use this measure, you need access to expensive gear such as a RacerMate Computrainer, SRM crank set, or one of the new Polar products, all of which enable a cyclist to use power as the measure of intensity. However, these devices can be expensive, require knowledge of basic sport science and are generally out of the reach of most aging athletes.