Power question - actual effort vs. perceived effort

[54ny77]

If putzing along on a computrainer at 200 watts, it is 200 watts regardless if I'm in a gear ratio & cadence combo that has me going 6 mph or 20mph? In other words, it's always 200 watts regardless of perceived effort?

[christian]

Yes. Assuming your power meter is properly calibrated and so on, 200 watts is 200 watts. (This is why power meters are useful). I have found that perceived exertion can vary significantly with ambient temperature and humidity and amount of sleep from the night before.

[tommyrod74]

If putzing along on a computrainer at 200 watts, it is 200 watts regardless if I'm in a gear ratio & cadence combo that has me going 6 mph or 20mph? In other words, it's always 200 watts regardless of perceived effort?

Wattage is completely independent of speed outdoors, or flywheel speed of a trainer.

Wattage = torque x frequency (cadence). For a given wattage, higher cadence = lower torque for each pedal stroke, and vice versa.

Some people find it easier to hold, say, 200 watts at a higher cadence in a lower gear, and some find the opposite easier (perceived exertion). Either way the workrate (wattage) is the same.

[ergott]

Technically yes, but if feels different when comparing climbing to flat terrain (at least for me).

I can sustain high power outputs for longer periods when climbing for some reason.

[Louis]

I'm no expert on this, but I'm pretty sure that the human body is more efficient pedaling at some cadences rather than others.

xxx watts at 2 rpm vs 90 rpm vs 125 rpm will all be different

[54ny77]

Thanks.

:beer:

[tommyrod74]

Technically yes, but if feels different when comparing climbing to flat terrain (at least for me).

I can sustain high power outputs for longer periods when climbing for some reason.

Most people can. The increased resistance of the hill makes it easier to maintain torque. The opposite is true on downhills for most people.

[makoti]

If putzing along on a computrainer at 200 watts, it is 200 watts regardless if I'm in a gear ratio & cadence combo that has me going 6 mph or 20mph? In other words, it's always 200 watts regardless of perceived effort?

Yes. It may be harder or easier to put out the 200w, but it's still 200w. That's what is great about training with power.

[tommyrod74]

I'm no expert on this, but I'm pretty sure that the human body is more efficient pedaling at some cadences rather than others.

xxx watts at 2 rpm vs 90 rpm vs 125 rpm will all be different

There's a range, certainly. 2 is too much torque; 200 is too much leg speed for the muscles to contract and relax quickly enough (for most humans).

Wattage is still identical.

I have clients do most intervals at the cadence they naturally gravitate towards, unless they naturally push 65-70 RPM all the time. Haven't run into that, though - most settle in at 80-100. Those with more developed cardiovascular systems (relative to muscular endurance) tend to higher cadences; vice versa for those with relatively better muscular endurance.

[54ny77]

i hate riding a trainer and would generally prefer sticking a hot fork in my eye vs. riding stationary, but had to use it the other day vs. no riding.

christian yeah i think it's calibrated correctly. i did the process 3 times and came within spitting distance for the resistance # (or whatever it's called). averaged out to about 1.7 or 1.8. initially felt a little tire slipping now & then but not much. smoothed out the pedal stroke and that took care of it. for what i was doing (just putzing along), the resistance level was close enough (i.e., if tire slipping was causing actual wattage to vary somewhat, i didn't really care).

[happycampyer]

If the tire is slipping, you either need to pump it up more or cinch down on the resistance. Iirc RacerMate recommends 110 - 120 psi. I've also found that the power curve doesn't feel as accurate below 80 rpm—ymmv.

[martl]

I'm no expert on this, but I'm pretty sure that the human body is more efficient pedaling at some cadences rather than others.

xxx watts at 2 rpm vs 90 rpm vs 125 rpm will all be different

There seems to be a sweet spot for cadence in respect to cycling efficiency, which is surprisingly low for you Lance/Vroomen adepts ;).

(The effect of cadence on cycling efficiency and local tissue oxygenation. (http://www.ncbi.nlm.nih.gov/pubmed/22648142))

I myself rode using a powermeter (SRM) a couple of years, when i was stil l racing at crappy amateur level. I rode a lot of climb TTs at that time. I found myself completely unable to reach the same wattage output in a flat TT compared to what i could do uphill.

[54ny77]

that's interesting observation. if you know you could output [x], but didn't, why not?

(unless it was simply an off day, and s&^%! can happen, of course.)




I myself rode using a powermeter (SRM) a couple of years, when i was stil l racing at crappy amateur level. I rode a lot of climb TTs at that time. I found myself completely unable to reach the same wattage output in a flat TT compared to what i could do uphill.

[benb]

I agree with most of what other said, it's a lot easier to maintain high wattage up a climb for me.

Among other things it also depends on the gearing you have (how tight the cassette is) and what the gradient is. When I'm on flat or downhill I often seem to get in a situation where you don't have quite the right gear to get a comfortable cadence at the right wattage when I'm trying to hold a particular power output.

I have a goal right now of doing an average power of 300w for 20 minutes. I really need to find a big steady climb to try it on. It doesn't take much downhill to make it really hard if I'm on a rolling course. (I'm stuck around 270 trying to do it local to wear I live, largely due to not being able to maintain wattage down the hills and/or if there is an intersection.) Intersections and corners tight enough to have to brake also make it really hard to keep power up.

For me perceived exertion seems related to:
- Sleep quality
- TSB
- Presence or absence of caffeine in my system
- Nutrition status

Within reason I can do the same wattage but when those are off it hurts a lot more.

[christian]

that's interesting observation. if you know you could output [x], but didn't, why not?

(unless it was simply an off day, and s&^%! can happen, of course.)

It's basically a function of load. On a hill, you have a fairly constant load due to gravity, which means you can apply torque on a near constant basis. If you consider 12-3-6-9 positions across the crank arm for two rotations, you're getting a torque value of 200w the whole time.

On a flattish course, little micro-descents and micro-tailwind-gusts work against you. Across two rotations of the crank, the effective power you are applying might be:

12: 200w
3: 195w
6: 200w
9: 196w
12: 201w
3: 200w
6: 196w
9: 194w

This wouldn't feel any different, but the normalized power over a 5 minute interval would be lower. Maybe you can aim for 205w and end up at 200w, but the variance of the effort is higher than under a steady load. It may also be that the variability of the efforts over small time intervals introduces a hysteresis effect in the strain gauges?

But undoubtedly it's true.

[martl]

that's interesting observation. if you know you could output [x], but didn't, why not?

(unless it was simply an off day, and s&^%! can happen, of course.)

if only i knew :) The study i mentioned above (and others) uses the term "rating of perceived exertion (RPE)". I could maintain my max effort (about 260-280W) at 190 BPM Heartrate (yep i know..) on a climb for 40-60min, but struggled to do the same in the flat for more than 15min, and it felt a *lot* harder. In both situations i would race as hard as i could, nothing at all left to give after the finish line (to the point of wanting to deliver the last meal if i could have mustered the power), but i still felt more "comfortable" uphill (if thats the correct word).

No idea whats the difference. cadence was lower uphill, elevation was *lower*. No idea what was the reason. Talent? Psychology? I'll never know.

Interestingly, teammates of mine reported the same feelings/effects.

[54ny77]

Gotcha. Makes total sense. Thanks for the explanation.

It's basically a function of load. On a hill, you have a fairly constant load due to gravity, which means you can apply torque on a near constant basis. If you consider 12-3-6-9 positions across the crank arm for two rotations, you're getting a torque value of 200w the whole time.

On a flattish course, little micro-descents and micro-tailwind-gusts work against you. Across two rotations of the crank, the effective power you are applying might be:

12: 200w
3: 195w
6: 200w
9: 196w
12: 201w
3: 200w
6: 196w
9: 194w

This wouldn't feel any different, but the normalized power over a 5 minute interval would be lower. Maybe you can aim for 205w and end up at 200w, but the variance of the effort is higher than under a steady load. It may also be that the variability of the efforts over small time intervals introduces a hysteresis effect in the strain gauges?

But undoubtedly it's true.

[54ny77]

totally get it. i don't ride with power meter but occasionally ride with people who do, and when they're saying they have to be in a particular range that day for whatever reason (call it 200 watts, for example), they stay there. sometimes for me it's ok, and sometimes it hurts bad, depending on the terrain, and when bad i just get shelled. :crap:

personally, i like 100-150 watts all day long.....

if only i knew :) The study i mentioned above (and others) uses the term "rating of perceived exertion (RPE)". I could maintain my max effort (about 260-280W) at 190 BPM Heartrate (yep i know..) on a climb for 40-60min, but struggled to do the same in the flat for more than 15min, and it felt a *lot* harder. In both situations i would race as hard as i could, nothing at all left to give after the finish line (to the point of wanting to deliver the last meal if i could have mustered the power), but i still felt more "comfortable" uphill (if thats the correct word).

No idea whats the difference. cadence was lower uphill, elevation was *lower*. No idea what was the reason. Talent? Psychology? I'll never know.

Interestingly, teammates of mine reported the same feelings/effects.

[happycampyer]

that's interesting observation. if you know you could output [x], but didn't, why not?

(unless it was simply an off day, and s&^%! can happen, of course.)

This may be somewhat related--I find it easier to maintain a particular wattage for a set period (e.g., 200w for 5 mins) when the CompuTrainer forces me (e.g., using the coaching software), versus when I have to maintain that same wattage for period myself. I realize it's different, but the when the CompuTrainer sets the wattage, it's sort of like climbing a hill.

[martl]

totally get it. i don't ride with power meter but occasionally ride with people who do, and when they're saying they have to be in a particular range that day for whatever reason (call it 200 watts, for example), they stay there. sometimes for me it's ok, and sometimes it hurts bad, depending on the terrain, and when bad i just get shelled. :crap:

personally, i like 100-150 watts all day long.....

Hehe :)

We used to ride a week-long event with a daily mountain TT for unlicensed riders (giro dolomiti) every year. The power meter told me i could maintain the same level of wattage daily over a week with only a slight drop - i just felt very different from day to day. I've learned fro using a PM that you can feel absolutely miserable and still be as fast as the other day when you felt great.
And the heart rate for a given wattage went down, as did the max HR - a sign of lack of endurance, i dont know. It was a hard test, doing your absolutely max for 7 days in a row for 40min-1hr40 at a day is something even TdF-Winners rarely have to do (riding man vs. man they will have situations in which they gotta do 110% or 120% to win, which we didn't - but i guess i got a glimpse of what thes fellas achieve). The boys competing for overall GC climbed 1500-1550hm/hr consistently, i'd have needed an output of 5,5W/kg to keep up. The Dottore Ferrari-customer usually won.

[benb]

It's basically a function of load. On a hill, you have a fairly constant load due to gravity, which means you can apply torque on a near constant basis. If you consider 12-3-6-9 positions across the crank arm for two rotations, you're getting a torque value of 200w the whole time.

On a flattish course, little micro-descents and micro-tailwind-gusts work against you. Across two rotations of the crank, the effective power you are applying might be:

12: 200w
3: 195w
6: 200w
9: 196w
12: 201w
3: 200w
6: 196w
9: 194w

This wouldn't feel any different, but the normalized power over a 5 minute interval would be lower. Maybe you can aim for 205w and end up at 200w, but the variance of the effort is higher than under a steady load. It may also be that the variability of the efforts over small time intervals introduces a hysteresis effect in the strain gauges?

But undoubtedly it's true.

Great explanation but IME the variations are larger than what you posted, maybe 1 order of magnitude greater. On a flat/rolling course it often feels like car or truck passing me can cause a temporary 50w drop in required power.

I don't have a PM that can report values around the "clock" but I also thought you had a much bigger variation in torque as the crank rotates.. a lot more in the "power stroke" of one leg than when the cranks are near vertical. Basically a lot when the pedals are near 3 and 9 and a lot less when they are near 12 and 6.

[christian]

Yes, I know. I simplified it and minimized the variance to demonstrate that even a very small drop in instantaneous power will have an impact on normalized power.

[54ny77]

Happy, I find it easier to never go harder than 150 watts if I don't have to.

(Although last weekend was grinding up Keeler Lane, and that hurt. Bad. You could have read War & Peace in the time it took me to get up the darned thing....)

:D

This may be somewhat related--I find it easier to maintain a particular wattage for a set period (e.g., 200w for 5 mins) when the CompuTrainer forces me (e.g., using the coaching software), versus when I have to maintain that same wattage for period myself. I realize it's different, but the when the CompuTrainer sets the wattage, it's sort of like climbing a hill.

[carpediemracing]

totally get it. i don't ride with power meter but occasionally ride with people who do, and when they're saying they have to be in a particular range that day for whatever reason (call it 200 watts, for example), they stay there. sometimes for me it's ok, and sometimes it hurts bad, depending on the terrain, and when bad i just get shelled. :crap:

personally, i like 100-150 watts all day long.....

I was looking at my Zwift "log" (sort of like the Strava training log). Apparently I average well under 100w for many of my training rides.

On 200w steady... that's super hard, to push to some uncomfortable power output. I like riding 100-150w avg and 170-190w is like serious race pace. When someone (friend, helped promote the Series for a number of years) wanted to go 250w steady it absolutely killed me.

The tough part was the unrelenting nature of the effort. 250w downhill. 250w flat. 250w uphill. The downhills were the hardest.

After a few minutes of this he completely shelled me.

That friend did a 3+ hour ride with someone else (former Cat 1, super strong but now retired from racing, Olympian in other sports, athletic guy) who could maintain 250w avg. Said it was brutal.

*edit Adding a list of my avg power from Zwift, all my training rides from August: 62w, 68w, 74w, 71w, 81w, 136w, 137w, 96w, 75w. 136w I went for the epic KOM (only one on the board so I got it even though it took me 40 min or something). 137w was a "Beer level" group ride where I got shelled pretty hard.

[r_mutt]

does the same wattage applied in different gears all work out to the same speed?

in other words, if you did 400 watts in your 53-18 and 400 watts in your 53-21, would they work out to the same speed (all other things being equal)?

[christian]

Yes. In reality, it's harder to sustain watts at particularly high or low cadences, but if you assume constant watts (power) at the crank, the speed would be the same (cadence would differ), with minute potential differences resulting from varying efficiency of chainline and amount of bend in the chain rollers. But for practical purposes yes; cadence would vary to get the number of watts; speed would be constant.

[ripvanrando]

I can maintain even power levels on flattish ground but not on the hilly rides. Isn't that normal.

On rolling terrain my power levels fluctuate and I have tried but can't hold a constant power level. I can back the power down on the up part of a roller but going down the inertia is to great and it seems I am playing catch up with my body fat. However, my perceived effort represents actual power. I know it is easier.

[ripvanrando]

does the same wattage applied in different gears all work out to the same speed?

in other words, if you did 400 watts in your 53-18 and 400 watts in your 53-21, would they work out to the same speed (all other things being equal)?

Yes.

[tommyrod74]

does the same wattage applied in different gears all work out to the same speed?

in other words, if you did 400 watts in your 53-18 and 400 watts in your 53-21, would they work out to the same speed (all other things being equal)?

Think of wattage as horsepower (the units of measure are interconvertible). In your car, it doesn't matter if you are in 3rd gear or 5th gear (at different RPM, obviously) - all else being equal, if horsepower is the same, so is speed (again, assuming identical conditions otherwise).

[weisan]

"I am not a robot."

We have heard Froome and maybe a few others expressed this a couple of times in the past.

[drewskey]

Don't forget that 200w inside on the trainer might feel harder than outside due to heat regulation issues. http://blog.trainerroad.com/training-smart-indoors/

[Mark McM]

There seems to be a sweet spot for cadence in respect to cycling efficiency, which is surprisingly low for you Lance/Vroomen adepts ;).

(The effect of cadence on cycling efficiency and local tissue oxygenation. (http://www.ncbi.nlm.nih.gov/pubmed/22648142))

I myself rode using a powermeter (SRM) a couple of years, when i was stil l racing at crappy amateur level. I rode a lot of climb TTs at that time. I found myself completely unable to reach the same wattage output in a flat TT compared to what i could do uphill.

The cited study is an example of getting the wrong answer because you asked the wrong question.

Efficiency/economy is not of anything more than academic interest to most cyclists - performance (either speed or distance) is not limited by efficiency/economy. Unless you are riding many hours a day several days in a row, you will not run out of energy. You may, however suffer muscle fatigue, cramping, glycogen depletion, etc.

A rider who weighs 160 lb. and has a body fat of 5% (8 lb. of fat) is carrying 28,000 calories of energy in fat reserves (3500 calories/lb of fat). If the rider expends 700 calories an hour riding, they will go through their energy reserves in 40 hours. Most people don't ride for 40 hours straight, let alone doing it at 700 calories an hour, so very few riders are likely to ever run out of energy.

It is factors other than energy efficiency that limits cycling performance. If a researcher is interested in finding the best cycling cadence, they need to use other criteria than energy efficiency.