# Measuring and comparing exertion levels in physically different people

I’m trying to think of a way in which I could measure the level of physical effort people in different groups (e.g. fat vs. skinny, men vs. women) exert on a performance task (e.g. cycling on an exercise bike). I want to be able to compare people in different groups according to some kind of standardized metric that basically accounts for how hard they try, but the differences in capabilities seems to present a hurdle in comparing groups that are physically different. For example, if these people were asked to cycle with maximum effort for a minute, how can I compare a person who is not in shape with someone who is in shape? They both try as hard as they can but one is simply more fit than the other. How can I gauge the level of effort without asking directly? Can this even be done?

Hi Cagey Drifter,

The best way I can think of doing this is to use cycling in conjunction with a power meter. A power meter is a device that measures the power output of the person riding the bicycle. Measuring this will allow you to directly compare the amount of effort that each person is putting out. In your example, if you compared the 1 minute wattage, at maximum effort, of a fit cyclist to an untrained person (for example), the fit cyclist will show a higher power output. You can use this data to directly compare between test subjects.

Some people may suggest using heart rate monitors. I would only use this if you had not others options available. A heart rate test would need to be conducted over a large time period, say half an hour or so, as heart rate lags behind effort, so short tests can give misleading results. In addition, results from heart rate meters can be clouded by temperature, fatigue, altitude, caffeine intake, time of day, stress, etc.

Your best option I think would to buy, or borrow or whatever a trainer with a power meter inbuilt. This way you don’t need to rely on your subjects having enough skill to actually ride a bicycle, and to set up a power meter in a bicycle is expensive (about \$1000 or so here is Aus, plus a bike of course). Something like the Kurt Kinetic series are well regarded (no plug intended).

There is actually a well regarded method of measuring exertion called rate of perceived exertion. In this, the test subject ranks how they feel on a scale of 1-10, or on the Borg scale, 6-20. This can be surprisingly accurate, some athletes have a finely tuned sense of RPE, however it is not much use if you are using untrained subjects, as they have usually not developed much of a sense of exertion.

There are a few resources on the internet about training with a power meter. The best is probably the book Training and Racing with a Power Meter by Allen and Coggan. Hope this helps you.

I was thinking some more about this and how you would actually measure exertion, and I’m not quite sure what you mean by measuring how hard they try.

How hard you are trying in one particular test is always relative you how much you can exert at maximum effort. So in a sense, you can’t compare level of exertion between people, because you ask your subjects to pedal as hard as they can, and that’s it. All your subjects are putting in the same amount of effort; the maximum they can. If you tell a fit cyclist and a couch potato to pedal at maximum effort, they are both exerting the same amount; their maximum.

What you are really asking is how to compare fitness, or some measure of performance at a particular level of exertion. This is where a power meter comes in, (or some other method like oxygen uptake).

Calculate each person’s individual maximum heart rate, then monitor their heart rates throughout the duration of the exercise and determine what percentage of their max HR they’re using and for what durations.

Out of curiosity, may I ask what sort of training type your subjects are using? i.e. steady-state cardio, high-intensity intervals, etc.

What are you asking? Who psychologically is pushing themselves harder (through pain, laziness, lack of energy, etc.) or who is performing closer to their physical limits (these being lower in untrained people), or what?

The psychological angle is difficult. For the physical, the common wisdom would say to measured heart rate divided by the maximum heart rate. But once you look into what the typical formulas for deducing maximum heart rate are, you’ll perhaps think they beg the question than answer it. But as a crude approximation, the heart rate approach has value. It is certainly used by many athletes when they ask how hard they are exerting themselves.

And although it may appear that the “% of physical limits” test would also answer the “how hard are they pushing themselves” question, it doesn’t necessarily. As a hypothetical, a person given certain drugs may be very lethargic or immobile or easily exhausted, and will not approach high heart rate despite giving an honest best effort.

How about a cardiac stress test?

Formulas using age subtracted from an arbitrary number are not accurate. The only way to get a true max heart rate is either in a lab or self administered tests.

To use myself as an example, I am 49 with a resting HR of 50 and a actual max HR of 187. 60%=132====80%=160

Predicted by formula I should have a MHR of 171 60%=122===80%=147

Be aware that once you stop exercising, heart rate drops very rapidly making taking your pulse by hand inaccurate. Use a heart rate monitor.