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thigger

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 #1 

Moxy-6x1k.png I've promised myself I would start using Moxy more this season, and have been having some success using it with ramp tests for zone setting. However, I'm curious about a 6x1k (treadmill) running session today - specifically the tHb reaction on the 5th interval.

Laps 1&2 are the warmup
3,5,7,9,11,13 are 1k intervals at a hard pace (slightly increasing from 1-3, 4th and 5th same as 3 but "broke" during the 5th and jogged to the end. 6th hard but much slower than the others)

 

My interpretation

1st (lap 3) - sudden SmO2 drop - probably not fully warmed up (also, SmO2 still rising during the warmup and doesn't hit its later peaks). Fairly minor tHb reaction but increases nicely during the interval suggesting appropriate cardiac/respiratory response.

2nd (lap 5), 3rd (lap 7) - more "normal" response (properly warmed up now). Smooth SmO2 drop and tHb rise suggesting intervals having their desired effect.

4th (lap 9) - SmO2 graph looks OK, but much deeper tHb drop this time and later recovery. Is this the start of the limitation that killed the next interval? Interestingly HR was only at 95%HRMax by the end of that interval, though I've been working night shifts which never helps! Low tHb suggests a cardiorespiratory limitation coming in

5th (lap 11) - this is the one where I failed. SmO2 curve looks OK but tHb plummets to a much lower value than any previous interval and shows no signs of coming back up until I stop. Again HR was only up to 95%HRMax, but the low tHb suggests cardiorespiratory limitation?

6th (lap 13) - this one was only at ~95% the speed of the others (and effectively after a longer rest), so it's no surprise that the SmO2 doesn't go down so much. However again the tHb drops and stays low for the entire interval.

Low tHb during intervals
This is my main query - is this simply a cardiac/respiratory limitation that needs training (or just resting away from night shifts!). Or are there alternative explanations? On nights my nutrition goes a bit messy so I was wondering if you'd see something similar if I'd burned up too much glucose on the first four intervals.

Alternatively could this just relate to muscle recruitment?


Grateful for any thoughts!


bobbyjobling

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 #2 
Moxy placement location?
I do night shift too and my last meal is about 9pm as it makes me feel better during the 12 hour shift. My training perceived effort is always higher after a night shift, but it could be that I only manage to get about 5.30 hours of sleep during the day.
Hiblbauer

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 #3 
* for better interpretation it is useful to also plot HR 
* I do not see any ventilatory limitation
   - smo2 keeps returning + getting higher that previous value, also higher than basal         
     (starting) smo2, the slower recovery is perhaps caused by motion of measured muscle
     group during recovery
   - to clearly see ventilatory limitation during recovery it is neccessary to avoid any motion
      of measured musle group.
* Lap 11 - in the middle of the bout you achieved arterial muscle occlusion, your cardiac
   output was not high enough to overcome the sum of pressure in the muscle capilaries (the
   venous outflow was not impacted as you do NOT see elevation on HHb )
   - reason for that: harder to guess without HR trend, but either cardiovascular limitation or
      muscle exhaustion leading to recruitment of more motor units (but due to lower
      desaturation not very probable)
* Lap 12, 13 complete loss of ability to sustain or recover homeostasis

Conclusion: cardiovascular limitation, training should had been stopped after lap 9, futher bouts only led to "cardivascular catastrophe" and if applied repeatedly may lead to overtraining.

Jan
bobbyjobling

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 #4 
Thb rebound after each load period gets progressively lower. Maybe blood pressure protection. But SmO2 on rest periods is increasing even with a decreasing tHb, blood flow velocity higher or left shift of O2 dissociation curve.
MoxyPhysiology

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 #5 
I agree with @Hiblbauer but could this be partially due to dehydration? I know I have a tendency to sweat a lot more when I am running on a treadmill, if you are already starting moderately dehydrated, and not rehydrating throughout the workout then blood volume is going to go down, which is indicative by the decreasing THb rebound signal during rest and since you are already maximizing stroke volume, by being at 95%HRmax, this might mean you just aren’t delivering adequate blood to the working muscle. 

Stuart percival

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 #6 
Where did you place the moxy ?
thigger

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 #7 
Really sorry - I didn't get any notifications until just now! Thanks for all the responses

I've uploaded a new chart including HR, speed and run cadence
I've also had a look back at previous times I've done this session and the tHb response behaves itself throughout (ie a sharp dip at the start of the interval before a slow rise during it)

@Stuart percival / @bobbyjobling - Moxy was on RF. I moved it there for cycling a while back (from VL), and I've just tended to stick with it for running for consistency. Cycling results on VL showed some really severe desaturations (below 10%) which is why I switched over.

@MoxyPhysiology - dehydration certainly seems plausible - night shifts in an air-conditioned hospital aren't great for staying hydrated! It seems possible that SV could go down in dehydration if HR is already near max, leading to a drop in tHb. Though not sure how that would explain the low tHb in the last interval (lap 13) where I was going a fair bit slower.

@Hiblbauer - obviously in retrospect there's something different about lap 9. Unfortunately the software I use (Perfpro) shows tHb live on a 10-12 scale so it's really difficult to see subtle differences like that. Are you suggesting that the slightly lower tHb in lap 9 would be cause to terminate the session even though the shape is fairly normal (ie dip followed by slow rise)? I agree that the shape in laps 11,13 is quite different. I'm interested in seeing how Moxy can be used to guide sessions rather than the way I've been using it so far mostly as an analysis tool.
Moxy-6x1k-b.png 

Hiblbauer

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 #8 

I was speaking of lap 11, although in the 9th lap you may find some signs that should raise alert - not being able to desaturate as low, the shape of th tHb is little bit different (delayed and blunted raise) eventhough the HR trend was pretty much the same as in the previus bouts (regarding the same "wattage" (speed x cadence) I could think of additional motor units recruitment in the 9th lap- but that is to much thinking = overinterpreting - with moxy it can happen easily, that you see more then there actually is to be seen)
there is no use in looking at absolute values of tHb, look for trends of the curves and shapes, and compare starting and ending points within th bout and with other bouts [wink]

PS I would go for VL in cycling 

MoxyPhysiology

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 #9 
To echo @hiblbauer, this could be a number of different things, (i.e. fiber recruitment shift, etc.) but it's more important not to get lost in the woods with interpretation. Look at the trends, from lap 9 and lap 11 you are no longer able to desaturate and during lap 11 THb follows a similar trend as in lap 9 (before you stopped the interval). This is indicative of some decrease in blood flow to the RF, if you aren't dehydrated, that blood has to be going somewhere else. To parse this out you could try to go back to the VL and do a similar workout, however, nutritional, and/or hydration status, could differ greatly. It could also just mean that your RF is not capable of maintaining that level of force output, even though you did slow down on the subsequent interval (your RF could be gassed).
CraigMahony

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 #10 
I am assuming you were doing a slow jog between the intervals. Might the effects seen also not occur due to prolonged foot contact on the treadmill due to fatigue? Therefore longer muscle compression reducing blood flow to the muscle during recovery.
thigger

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 #11 
@Hiblbauer - I used to use VL for cycling but I could easily get the SmO2 below 10%, and once it hits zero it starts behaving very oddly. RF gives me results that look a lot more like other people's

@MoxyPhysiology, CraigMahony - seems very plausible. I've done this workout loads of times though and the pattern is normally much more like the first couple of intervals (ie gradual rise in tHb during the interval) - this is the first time I've seen this response. (also I don't normally quit!)
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