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Single-sided power meters - learned imbalance?

 
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straightouttabrompton




Joined: 26 Jul 2013
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PostPosted: Thu Dec 13, 2018 2:22 pm    Post subject: Single-sided power meters - learned imbalance? Reply with quote

A friend suggested this to me the other day when we were using the wattbikes at the gym.

If you train with a single sided power meter - where the measurement for just one leg is doubled to give your power, on the assumption that you have a 50/50 L/R balance. Is it possible/ likely that you will develop an imbalance where you put more power out through the leg that has the sensor on it.

We were thinking that through repeated training you could sub-consciously learn that if you push harder on the sensor/ measured side (over the other) your power numbers go up for less effort than if you push equally on both pedals. So you are almost "rewarded" for the imbalance because the power numbers on your display go up for less total effort on your part.

I know there is lots of criticism for single sided power meters on the basis that they are inaccurate if you have an L/R imbalance because of injury or bio mechanics. But could they help create an imbalance?
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Wheezy




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PostPosted: Thu Dec 13, 2018 3:06 pm    Post subject: Reply with quote

Not in my (limited) experience. Iíve got a single sided PM and while I have the watts displayed prominently on my Garmin head unit, I tend to just check in every few minutes to see where my power is, rather than staring at it slavishly trying to get my numbers up or down. Iím comparing NP as a trend over time rather than what Iím doing from minute to minute with each leg. Iím simply not focusing on left-right balance. The few times that I have used a wattbike I have found their display much more distracting and probably more likely to end up with me pushing harder on my weaker side or vice versa.
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mattsurf




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PostPosted: Thu Dec 13, 2018 3:27 pm    Post subject: Reply with quote

I think that it is highly unlikely.

As I have dual and single sided PM, I know that I ride with a 50:50 balance, however, it was interesting to see that when I had piriformis syndrome in October, that my balance went to 52:48, even though it didn't appear to cause any discomfort on the bike
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Pedro Peru




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PostPosted: Thu Dec 13, 2018 3:53 pm    Post subject: Reply with quote

mattsurf wrote:
I think that it is highly unlikely.

As I have dual and single sided PM, I know that I ride with a 50:50 balance, however, it was interesting to see that when I had piriformis syndrome in October, that my balance went to 52:48, even though it didn't appear to cause any discomfort on the bike

I hope you complied with the 52 and implemented the will of your legs!
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explorerJC




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PostPosted: Thu Dec 13, 2018 8:49 pm    Post subject: Reply with quote

If you have spent time in the saddle before getting the PM, then probably not, but if your sole exposure to cycling is through a single measuring device, then it is possible..

..but, as we have seen with the new "coached" remote sessions, developing skills are secondary to immediate outcome...
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straightouttabrompton




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PostPosted: Fri Dec 14, 2018 4:40 pm    Post subject: Reply with quote

perhaps more of a risk if you do a lot of interval training (perhaps zwift training sessions, trainer road that kind of thing) where you are trying to ride at certain target power numbers for a given length of time?

example - your zwift session says you have to ride 300w for 20mins, but your body learns (not through consciously thinking about it) that if you work slightly (imperceptibly to you) harder with the leg that is measured by your PM, you can achieve this number on the screen, while feeling better for it.
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duckhen




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PostPosted: Sat Dec 15, 2018 7:26 am    Post subject: Reply with quote

My own experience with single sided was that at high cadence all worked well but at lower cadence, so simulated climbing, there would be an awareness that the Ďpowerí side leg was becoming more dominant.
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mattsurf




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PostPosted: Mon Dec 17, 2018 12:17 pm    Post subject: Reply with quote

Pedro Peru wrote:
mattsurf wrote:
I think that it is highly unlikely.

As I have dual and single sided PM, I know that I ride with a 50:50 balance, however, it was interesting to see that when I had piriformis syndrome in October, that my balance went to 52:48, even though it didn't appear to cause any discomfort on the bike

I hope you complied with the 52 and implemented the will of your legs!


Yes of course I did, and my power dropped by 20%
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PCP




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PostPosted: Mon Dec 17, 2018 5:14 pm    Post subject: Reply with quote

Why would you deliberately chase a number with one leg? Surely no-one would deliberately do this!
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jibberjim




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PostPosted: Mon Dec 17, 2018 5:49 pm    Post subject: Reply with quote

PCP wrote:
Why would you deliberately chase a number with one leg? Surely no-one would deliberately do this!


The whole point is that it wouldn't be deliberate.

If you assume your body is pretty much hard wired to be as lazy as possible, which makes sense from an evolutionary perspective, then it will try to achieve everything in as easy a way as possible. If you go out with an aim to get the highest possible watts, and you feedback to it that any work you do half the time is ignored, it is likely to learn that, and stop working that half the time.

I'd say it's just another reason not to chase a number or buy a single sided power meter, but I personally doubt the effect would be that significant either, because you're not really purely chasing a power number even in the most constrained scenario.
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Jorgan




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PostPosted: Tue Dec 18, 2018 9:40 am    Post subject: Reply with quote

I'd say there could be something in it. My first PM was an Ergomo, which I got not long after getting back into Triathlon; it's a single-sided BB system. Anyway, fast forward to 2014 when I bought a Power2Max and my left leg was stronger than my right. I would say after nearly 5 years, I've 'trained' that bias out now, but it certainly existed in the early days of having L/R power.
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explorerJC




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PostPosted: Tue Dec 18, 2018 9:48 am    Post subject: Reply with quote

Why do you have to produce equal power from both legs??? It may be ideal but there are a multitude of reasons why you may not be able to...
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Jorgan




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PostPosted: Tue Dec 18, 2018 10:25 am    Post subject: Reply with quote

Leg-length discrepancy is not uncommon, and I think that will have a bearing. I know mine are different.
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stenard




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PostPosted: Tue Dec 18, 2018 12:21 pm    Post subject: Reply with quote

explorerJC wrote:
Why do you have to produce equal power from both legs??? It may be ideal but there are a multitude of reasons why you may not be able to...

Of course. DCR makes reference to that frequently, and there is not yet any science that I am aware of that indicates 50:50 is in any way optimal.

But what is being hypothesised here is that your body could in effect subconsciously adapt such that you get no fitter or stronger overall, yet you have the appearance of progression because your single sided watts are growing. That's detrimental. It's creating an unnatural imbalance for no improvement in performance.

Strangely, to achieve that result, your left leg would have actually had to have got stronger to output more watts on just that side that then get doubled. The issue is that if there is no incentive for the right to also get stronger, as Jim says, your body will potentially take the easy option. Yet dual sided may have motivated an equivalent improvement in the right side as well, and hence you are overall able to output more watts, and therefore faster.
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