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Dr Matt

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 #16 
Yes, watched that video before. Just rewatched it, maybe bike fit impacting.

This could be interesting. Comparing two time trials on same course. On TT bike. Moxy sensor located on right hand quad (same location as previous tests).  Maybe relevant - maybe not?

TT.png 

Apart from being 6 months apart and potential differences in fitness, fatigue and exact sensor location, the main difference is in the June race I took a "beetit" shot 4 hours before the race.

I know nitrates decrease blood pressure, cause arteries to vasodialate among other things.  Result shows ThB up, HR up, SMo2 up (initially), power up a couple of watts overall. So better muscle oxygenation at expense of a higher HR. Hmmm.......

CraigMahony

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 #17 
Cannot really see the images. Instead of attaching a file, put it directly into the reply and the image will be much larger.

I think that you should trial a higher riding position, even just in the warm up of a ride, to see if you get higher SmO2 (possibly caused by a reduced build up of HHb).
Dr Matt

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 #18 

Here is another interesting result, maybe related, maybe not. This is a hilly ride I do once every week for many years. The hills are short and steep. This data covers 1 hour. Moxy sensors mounted on right quad and left hamstring.

hills.png 

The hardest climb is the one around the 2500 to 2700 mark, the climb ramps up in gradient. Even with a 39/28 combo cadence is low and power high.

hills_zoom.png 

This results in a very low SMo2 by end of climb in order of 6% and HR getting a few beats away from max.

The interesting thing is the quad ThB, I don't really see this trend in data normally.  initially just after the load is reduced it drops down then shoots up when load is removed completely, all while HR is dropping. Evidence of an outflow occlusion? Why would this only show up during high power intervals?


ryinc

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 #19 
Dr Matt

On your last post. Thb drop due to outflow restrictions normally have (1) an immediate tHB reaction and (2) are normally preceding by an increase in THb as the blood pools up.

I don't see either of those taking place here (THb drops well after Sm02 is already increasing) and THb does not seem to be rising either).

Did you perhaps change position e.g. standing to sitting etc, and that potentially caused it?

Regards
Ryan


Dr Matt

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 #20 
Sitting down the entire time -fairly sure. I actually rarely stand to climb, maybe that is the part of the problem reading some other posts on here, being I dont shift around enough......

That hill kicks up to somewhere around 15%+, so in general I would be sitting well forward (on the saddle of the nose) to "get over" the gears, gripping tight to the bars and when I reach the top and it flattens I would shift back and relax upper body.

So after reading some threads on here I am leaning towards your thinking that it could be a position and/or intermuscle coordination issue with the VL.

This post by Juerg is interesting  http://forum.moxymonitor.com/post/case-intermuscular-coordiination-with-nirs-8486252

My assumption is if the power is constant then the changes Juerg made are a combination of sitting upright vs really low, moving forward and backward on saddle, standing up vs sitting down, low cadence vs normal vs  high cadence? I will test these myself on VL, RF and RB anyway but any extra suggestions or leads appreciated. 

Dr Matt

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 #21 
Getting some interesting results with altering position on bike while altering cadence.

One interesting example is Quad VL & RF muscle response while standing and increasing cadence. I can make the two muscles desaturate a good amount while holding very low power and a fairly low heart rate - normally to get the VL to go to this level of oxygen my HR is about 170 and power is 350w+, can never normally get the RF to desaturate this much.

So first question - can I just confirm that from a physiological point of view these two conditions are the same?
1/ VL desaturing to 15% Smo2 under the condition of sitting, 90rpm, 350w and 170bpm
2/ VL desaturing to 15% Smo2 under the condition of standing, 90rpm, 190w and 150bpm?

Second question - out of interest, why does this condition happen standing but not sitting? Is this because when standing as leg speed increases the driving leg needs to devote more and more power to lifting the other leg + body mass as it can't be lifted fast enough? 


**********

Picture 1 - Sitting in normal riding position on road bike, increasing cadence. Using three Moxy sensors at same time on VL, RF and BF (hamstring). Interesting that HR remains stable, ThB drifts down for RF and BF but the biased oxygen chart shows increasing numbers.

sitting.png 

Picture 2 - Standing and increasing cadence. Using three Moxy sensors at same time on VL, RF and BF (hamstring). HR up and oxygenation down with increasing cadence. Very different response to similar power/cadece numbers from sitting position.

standing.png 

ryinc

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 #22 
Hi Dr Matt

Really fascinating experiment - this is what makes Moxy so fun.

It surely cannot be that all aspects physiologically VL@15% at 150bpm is identical to VL@15% at 170bpm.However  if we narrow the statement to training of utilisation of the local muscle, then i think these are notionally physiologically equivalent in that narrower interpretation.

(as an aside here is a thread with similar ideas but different exercise).
http://forum.moxymonitor.com/post/desaturation-at-low-intensity-8399431?&trail=15

In both cases, i found this type of idea on the forum fascinating - how you can train utilisation at low intensity without putting another system in difficulty. Basically what Juerg always says around any physiological manipulation in the lower intensity levels is possible because everything is in control. It's simply a function of knowing how to manipulate them, and perhaps now this is another ingredient to work with for you. There was an interesting discussion a while back where Juerg explained how with COPD patients they would do single leg drills because because this would help ensure that the cardiopulmonary system was not at its limit (since its unlikely that would be the limiter if only 1 leg was doing work).

Did you start picture 1 - warmed up already, or was this done as you got on the bike? I am wondering whether it may be possible that the increasing Sm02 is a function of the delivery system warming up rather than the cadence impact?

If not warmed up, i think it probably speaks to inter-muscular co-ordination, presumably as the cadence increases you use slightly more of the VL muscle, so Smo2 drops slightly on that muscle and rises on the others as they are used less?

In the standing case - I'm not sure whether it is the specific reason you mention (i.e. around one leg having to pull the other up) but perhaps it could be generalised to  some level of inefficiency in the muscle recruitment in the pedal stroke, and this becomes more and more exaggerated as cadence increases. Presumably Heart rate tries to compensate to increase delivery.

Now what would be interesting is if you incorporated specific high speed standing drills for say 6-8 weeks into a training programme and then at the end did the same experiment to see if anything changed. Quite a lot of effort in the name of science though!




Dr Matt

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 #23 
Thanks Ryan.

That is my plan to do lots of standing high cadence drills to really work the VL and RF muscle. Its a good time for me to do trainer drills as the new baby means not much road time :-)

Picture 1 does baffle me a tad and I have not had enough time to dwell on it. It seems odd that HR stays basically flat, the ThB drops in RF and BF but SmO2 increases in those muscles? So that must mean the overall oxygenation of the blood in my body increases. It does look like as cadence increases the VL is leaned on more and more.

Yes, both sessions warmed up as I wanted to remove influence of cold start. In picture 1 (sitting) I did 10 mins of slow warmup about 80rpm, 130-150w + trainer calibration. In picture 2 (standing) I also did a warmup about the same 80rpm, 130-150w + trainer calibration of 10min in length. I made a bit of a mistake in standing test that I went straight from sitting to standing at 640second mark when I should have rested 1min before starting but I dont think this impacts overall trend.

I should have mentioned that I sat down during each 1min recovery load during standing test. Sitting test was conducted 24 hours after standing test.

*****
sitting2.png 

standing2.png 

ryinc

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 #24 
Quote:
Picture 1 does baffle me a tad and I have not had enough time to dwell on it. It seems odd that HR stays basically flat, the ThB drops in RF and BF but SmO2 increases in those muscles? So that must mean the overall oxygenation of the blood in my body increases. It does look like as cadence increases the VL is leaned on more and more.


For RF and Hamstring, think about the different ways Sm02 could increase. Two hypothetical situations on the opposite end of the spectrum. A - utilisation stays the same but delivery increases. B - delivery stays the same but utilisation reduces.  How would A vs B most likely show up, particularly in THb, Oxy/Deoxy traces. Which seems closer to what you are observing? 

There are other options for Sm02 increases (e.g. respiratory manipulations) but not relevant here i think.
Dr Matt

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 #25 
A - utilisation stays the same but delivery increases. SmO2 stays level, ThB increases, therefore Oxy and DeOxy both increasing
B - delivery stays the same but utilisation  reduces. ThB stays flat but SmO2 increasing. Therefore Oxy increasing and DeOxy reducing

So B is closest scenario..... just seemed strange at first pass that the faster I pedal when sitting the less those muscles get involved as i would have thought opposite was true (as shown in standing example). But Power = Torque x rpm, so for same power the higher the rpm the lower the torque required, so when sitting maybe the VL can cover force delivery without needing to engage the RF and BF??
ryinc

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 #26 
For A - if utilisation stays the same why would Deoxy increase?

Keep in mind there are other scenarios - e.g. C - local delivery to specific muscle reduces, but utilisation reduces more than delivery reduces. Think how such a situation might show up in the various traces. I just used A and B as two examples.

CraigMahony

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 #27 
Another possibility to consider is reduced venous return return when standing. With my track and field athletes I have at time found that they had no desaturated as much as I though but rather deoxygenated blood was pooling and not being pumped back to the heart. This might be be happening in the standing position. (See some of the posts on this) It might become clearer if you graph Oxy VL v Deoxy VL, similarly for hamstrings.
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