Consistent Power Output

rflynnr

I'm currently working my way through Joe Friel's Bible and have quickly realised that my lack of a power meter is going to pose problems in applying muich of his advice. However, I'm equally confident that the 4-figure sum purchasing one demands is beyond both my means and, frankly, beyond what a cyclist with my limited ambitions requires.

That said, I'd still like to establish some kind of objective basis for measuring training progress. I purchased rollers last week and have enjoyed them significantly more than previous experiences with a turbo. I also have a Garmin Edge 705 with HRM and there's a cadence sensor coming in the post.

One thing I would like to establish is the extent of my "cardio drift" (as I believe Friel terms it), i.e. the extent to which heart rate increases over an extended period relative to power output. In other words, the extent to which the heart has to work harder to maintain the same power output.

Which brings me to my question: given that I'm on resistance-free rollers, can I use a combination of gearing and cadence as a proxy for measured power output in watts? I.e., if I'm pedalling in 53/14 and maintaining a cadence of 90 rpm on flat rollers will my output always be the same? Or are there other factors that I'm missing?

(With apologies for long-windedness and incoherence of this.)

Lumen

rflynnr wrote: »

One thing I would like to establish is the extent of my "cardio drift" (as I believe Friel terms it), i.e. the extent to which heart rate increases over an extended period relative to power output. In other words, the extent to which the heart has to work harder to maintain the same power output.

Cardiac drift, I think. As I understand it the heart isn't working harder as such, it's just beating faster with a lower stroke volume, essentially adjusting to the load.

I think Friel says that high cardiac drift is an indication that not enough base aerobic training has been done. "Base" in this sense means aerobic endurance training for sustained power, probably not LSD. I'm not entirely convinced about this analysis myself, but he is obviously pretty qualified.

rflynnr wrote: »

Which brings me to my question: given that I'm on resistance-free rollers, can I use a combination of gearing and cadence as a proxy for measured power output in watts? I.e., if I'm pedalling in 53/14 and maintaining a cadence of 90 rpm on flat rollers will my output always be the same? Or are there other factors that I'm missing?

It should be the same, but the rollers surely can't be "resistance free" or you'd be relying entirely on tyre rolling resistance, spoke drag and drivetrain losses.

You could probably do a few longish (say 20 minute) intervals at different speeds and work out training zones from the interval-end HR. Or just borrow a power meter to do the "calibration".

edit: which rollers do you have?

cdaly_

When you say "resistance-free rollers" do you mean there is no drag? Is this not just the equivalent of turning the pedals with the wheel off the ground? I would have thought it would be hard to have any workout that way.

Or is this some other meaning for the term "resistance-free"?...

That said, your steady cadence in the same gear with the same resistance should equal the same power output...

mloc123

Maintain the same 'speed' on rollers should indicate cardiac drift or not. So aim to maintain whatever HR for 90 minutes on the rollers, your 'speed' should remain constant... if it drops off towards the end while keeping the same HR you are showing signs of drift. Heat will affect your heart rate, so maybe allow for a small increase as you get warmer or else get alot of fans.

rflynnr

I didn't mean to suggest that the rollers are entirely frictionless, rather that there's no way of altering the resistance. That said there isn't much "built-in" resistance - it's akin to cycling on a flat road with a perfect surface in no wind. Switching through the gears is the only way to change the resistance but I haven't found a problem in getting a decent workout. Once I've warmed up for about 15 minutes, I tend to operate across heart zones, 4, 5 and (for maybe a minute at a time) 6. The last is achieved by going into 53/12 with a high cadence (100 plus) but I'm still not going flat-out although I'm comfortably into the anaerobic zone.

@Lumen: you're right to suggest that I'm looking to establish a base of aerobic endurance training. I didn't quite follow your point about working out power zones from interval end HR though: how would HR translate into wattage? (I ask this knowing I've missed the point.)

Lumen

rflynnr wrote: »

@Lumen: you're right to suggest that I'm looking to establish a base of aerobic endurance training. I didn't quite follow your point about working out power zones from interval end HR though: how would HR translate into wattage? (I ask this knowing I've missed the point.)

Zones are zones. Obviously HR is measuring effort less directly, takes a while to ramp up, and is prone to variation depending on various things going on with your body, but since physiological adaption occurs on a continuum it doesn't really matter whether you're riding at 85% or 90% of threshold HR (or whatever), you'll still get much the same training effect.

Speed is a poor analogue for power when training outdoors, since it's affected by gradient and wind, but indoors power is directly correlated with speed on the rollers (though the relationship may not be linear), and this relationship should be constant from day to day.

This means that if you are targetting a constant effort tempo interval, and you've decided that tempo for you means perhaps 165bpm, just find a speed that sees your HR rise to around 165bpm steady, and start the interval at that speed.

I think.

rflynnr

Gotcha.

niceonetom

Is drift always upwards? Sounds like a strange question, I know, but turboing makes me ponder these things...

When attempting tempo work on the turbo I find that if I maintain a constant cadence at whatever resistance my HR gradually declines as the time (slowly) ticks by... to maintain my HR where I want it I have to increase the resistance as the interval goes on (or up the cadence, which has the same effect). I'm talking about a drop of maybe 5-10 bpm over about as many minutes. Curious.

Anyone else experience this? Do turbos gradually lower resistance as they're used? Something to do with the tyres getting warm perhaps? lazy magnets? Or is my heart anomalous?

Apologies for deviation from topic, rflynnr, I too am trying to train with HRM in a world obsessed with "watts".

rflynnr

niceonetom wrote: »

When attempting tempo work on the turbo I find that if I maintain a constant cadence at whatever resistance my HR gradually declines as the time (slowly) ticks by... to maintain my HR where I want it I have to increase the resistance as the interval goes on (or up the cadence, which has the same effect). I'm talking about a drop of maybe 5-10 bpm over about as many minutes.

No problem - it's hardly a significant deviation. I've experienced something similar even doing interval training: I get my heart rate to where I want it for say five minutes but although I'm sitting in the same gear and working to the same cadence the HR starts to fall, requiring me to drop a gear or up the cadence to maintain a consistent HR. I had assumed that it was caused by the body adjusting to a tempo after having made an increased effort to get to that tempo in the first place.

blorg

I certainly find it harder to maintain a high heart rate at the end of a sustained (all day effort)... but my power may well have gone down also at that point, who knows.

niceonetom

rflynnr wrote: »

I had assumed that it was caused by the body adjusting to a tempo after having made an increased effort to get to that tempo in the first place.

I didn't really think it was significant, just not what I was expecting... it tends to become marked after the first 10 or 15 minutes of tempo so I don't think it's a recovery from the overshoot in effort that might happen while trying to get up to the right HR. Maybe it is just settling in to the effort.

@blorg - I'm certainly familiar with the difference in the way 165 feels early in the ride (:fine) and what it might feel like 5 hours (:hellish) later (usually on the bloody bastarding pogio). But on short turbo sessions (maybe an hour) I wouldn't expect this much variation, and given that I'm actually pushing a bigger gear against the resistance to maintain the same HR I think my power@xHRM is actually going up as time passes. Unless the turbo loses resistance as time passes anyway...

leftism

rflynnr wrote: »

I'd still like to establish some kind of objective basis for measuring training progress.

I'm not sure if cardiac drift is of that much significance in terms of aerobic adaptation to training.

Cardiac drift is the term given to the slow gradual rise in heart rate at a fixed workload during long duration endurance exercise. It is due to a reduction in stroke volume. (Cardiac Output= Heart Rate x Stroke Volume) so in order to maintain a constant cardiac output when SV is being reduced, heart rate must increase. The reduced stroke volume is due to dehydration or an increase in core body temperature. Maintaining hydration status by replacing lost fluids during endurance exercise should eliminate or definitely reduce your cardiac drift. As long as you are hydrated, core body temperature should maintain homeostasis (albeit a higher homeostasis due to exercise), unless its hotter than 25 degrees outside, which rarely happens in Ireland. Then it can be a problem.

I don't see how aerobic training would reduce cardiac drift to any great extent. Improved hydration, and/or acclimatisation to a hotter climate WILL reduce cardiac drift.

As for measuring your cardiac drift. This is problematic due to poor test-retest conditions within your own body. If you are hydrated and STAY hydrated during the endurance exercise, drift should be very slow. If you are dehydrated or become dehydrated, it will be much faster. But neither of those scenarios has anything to do with your fitness level though...

A good objective measure of training adaptation which has been mentioned here in the past is find a flat 20km course and timetrial over it. Or distance covered in 30mins. Your work-rate in a piece like this will pretty much level out at close to threshold (or you'll blow up before the finish). So any improvement you see in an effort like this can be correlated to increased power or speed at aerobic threshold.

mloc123

niceonetom wrote: »

I didn't really think it was significant, just not what I was expecting... it tends to become marked after the first 10 or 15 minutes of tempo so I don't think it's a recovery from the overshoot in effort that might happen while trying to get up to the right HR. Maybe it is just settling in to the effort.

@blorg - I'm certainly familiar with the difference in the way 165 feels early in the ride (:fine) and what it might feel like 5 hours (:hellish) later (usually on the bloody bastarding pogio). But on short turbo sessions (maybe an hour) I wouldn't expect this much variation, and given that I'm actually pushing a bigger gear against the resistance to maintain the same HR I think my power@xHRM is actually going up as time passes. Unless the turbo loses resistance as time passes anyway...

Is it a fluid trainer? I'm guessing as the fluid heats it becomes thinner and could lose some resistance?

niceonetom

mloc123 wrote: »

Is it a fluid trainer? I'm guessing as the fluid heats it becomes thinner and could lose some resistance?

No, it's magnetic.

Ryaner

rflynnr wrote: »

However, I'm equally confident that the 4-figure sum purchasing one demands is beyond both my means and, frankly, beyond what a cyclist with my limited ambitions requires.

I got my first powertap built into an open pro rim for just a bit above 500 Euro. They ain't too expensive these days once you have a Garmin.

Oh and consistent power output on the road is impossible. You can stay in a range if the road is flat and the wind is constant but that is rarely the case.

mloc123

Ryaner wrote: »

I got my first powertap built into an open pro rim for just a bit above 500 Euro. They ain't too expensive these days once you have a Garmin.

Oh and consistent power output on the road is impossible. You can stay in a range if the road is flat and the wind is constant but that is rarely the case.

Details on that? New or used and where from?

Ryaner

mloc123 wrote: »

Details on that? New or used and where from?

Hub was an Elite+ new from EliteFitness in the UK - Prices were lower before xmas. It was built up by Humphries in Finglas.

Beasty

Ryaner wrote: »

Oh and consistent power output on the road is impossible. You can stay in a range if the road is flat and the wind is constant but that is rarely the case.

Agreed

I find that even on something reasonably flat if you have the power display on "instant" the reading will be all over the place. I keep mine on 30s moving average and try and maintain something reasonably steady.

I think the only way you can get something reasonably constant is on a steady incline, where you try and keep a constant force on the pedal

Now I have the powermeter I don't even bother displaying my speed on the Garmin any more - just have the 30s power, 3s power, time and heart rate (which gives me a reasonably large display for the power output)

Lumen

Ryaner wrote: »

Hub was an Elite+ new from EliteFitness in the UK - Prices were lower before xmas. It was built up by Humphries in Finglas.

Some other options:

wheelsmith.co.uk: £645 for wheel only (Ambrosio or IRD rim).

cyclepowermeters.com: £725 for wheel only (Mavic rim, I think).

rflynnr

I am, by any standards (and especially by local ones), a very average cyclist. But now, Ryaner and Lumen have tempted me and I find myself contemplating spending €700. I thought spending €450 on a pair of wheels was purchasing beyond my ability. How has it come to this?

rflynnr

leftism wrote: »

The reduced stroke volume is due to dehydration or an increase in core body temperature.

I'm not doubting the basic biology of what you're outlining (mainly because I'm not a medic/physio) but is it possible that the reduction in stroke volume could itself be reduced by training? I kind of thought that was the intent of Friel's suggestion: that, like any other muscle, the efficiency of the heart could be improved through training.

Or is he just plain wrong?

Lumen

rflynnr wrote: »

I am, by any standards (and especially by local ones), a very average cyclist. But now, Ryaner and Lumen have tempted me and I find myself contemplating spending €700. I thought spending €450 on a pair of wheels was purchasing beyond my ability. How has it come to this?

You're the one that started banging on about cardiac drift. :pac:

Honestly, you don't need a power meter - HR zoning is fine. So what if the power goes up or down a bit? It really makes no difference.

That said, you can take my powermeter from my cold dead hand, as Charlton Heston would have said if he'd been a cycling geek rather a gun nut.

rflynnr

Lumen wrote: »

Y
That said, you can take my powermeter from my cold dead hand, as Charlton Heston would have said if he'd been a cycling geek rather a gun nut.

Is that an offer?

Lumen

rflynnr wrote: »

like any other muscle, the efficiency of the heart could be improved through training.

You're not training your cardiac muscle, you're training your skeletal muscles. Your cardiovascular system is mostly just along for the ride.

blorg

niceonetom wrote: »

No, it's magnetic.

Are you wearing one of these?

blorg

Lumen wrote: »

You're not training your cardiac muscle, you're training your skeletal muscles. Your cardiovascular system is mostly just along for the ride.

Your cardiovascular endurance certainly improves with training, and this is somewhat separate from your skeletal muscles, no? I know from starting running being a fit cyclist my cardio system was fine but the skeletal muscles were not up to it!

Lumen

blorg wrote: »

Your cardiovascular endurance certainly improves with training, and this is somewhat separate from your skeletal muscles, no? I know from starting running being a fit cyclist my cardio system was fine but the skeletal muscles were not up to it!

What is "cardiovascular endurance"?

blorg

Lumen wrote: »

What is "cardiovascular endurance"?

The ability of the heart to provide oxygen to muscles during physical activity for a prolonged period of time.

Equivalent terms: Aerobic fitness, aerobic capacity, and endurance.

http://en.wikipedia.org/wiki/Aerobic_exercise#Aerobic_capacity

victorcarrera

niceonetom wrote: »

...When attempting tempo work on the turbo I find that if I maintain a constant cadence at whatever resistance my HR gradually declines as the time (slowly) ticks by... to maintain my HR where I want it I have to increase the resistance as the interval goes on (or up the cadence, which has the same effect). I'm talking about a drop of maybe 5-10 bpm over about as many minutes.
...+ I didn't really think it was significant, just not what I was expecting... it tends to become marked after the first 10 or 15 minutes of tempo so I don't think it's a recovery from the overshoot in effort that might happen while trying to get up to the right HR. Maybe it is just settling in to the effort.

@rflynnr
I've experienced something similar even doing interval training: I get my heart rate to where I want it for say five minutes but although I'm sitting in the same gear and working to the same cadence the HR starts to fall, requiring me to drop a gear or up the cadence to maintain a consistent HR.

Could it be you are not warming up properly. Warm up time increases with age too if this applies.
See this link

warm up

Ryaner

rflynnr wrote: »

I am, by any standards (and especially by local ones), a very average cyclist. But now, Ryaner and Lumen have tempted me and I find myself contemplating spending €700. I thought spending €450 on a pair of wheels was purchasing beyond my ability. How has it come to this?

Watch out, I bought a power meter for my commuter/winter trainer, then a month later ended up with http://www.boards.ie/vbulletin/showpost.php?p=64250140&postcount=1699 :P

Lumen

blorg wrote: »

The ability of the heart to provide oxygen to muscles during physical activity for a prolonged period of time.

Equivalent terms: Aerobic fitness, aerobic capacity, and endurance.

http://en.wikipedia.org/wiki/Aerobic_exercise#Aerobic_capacity

I don't see the relevance of cardiac output to cycling training. Your heart gets stronger with training. So what? Does this make you faster?

Much of training is about focusing on limiting factors. The heart is not a limiting factor in endurance exercise, or else you'd be able to cycle at 200bpm for six hours straight. The fact that you can't is nothing to do with your heart.