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CraigMahony

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 #1 
Hi All

I was hoping to get a second opinion on some Moxy feedback from a Track session I had a sprinter do. The section I am concerned with is the middle section of the 8 deeper SmO2 drops. This was the main part of the session and was 8 x 150m @ 80% effort, walk 50m to the next starting point and wait until her heart rate is down to 130 bpm then go again.

As you can see from this graph from Golden Cheetah, the overall tHB rebounded to about the same each time after each repetition. However, after the 5th repetition the SmO2 gradually rebounds less each time. We can see that the O2Hb also rebounds less each time and that the HHb reduces less each time causing the SmO2 figure to be reduced.
So my question is,'What is causing this?'. Is it increased blood pooling? If so why? Are there any other reasons people can think of that might cause this?
Hayley20170613-1.jpg

 
Attached Files
csv Hayley20170613.csv (101.84 KB, 6 views)

ryinc

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 #2 
Hi Craig

First, i see the THb slightly differently - to me it looks like a gradual upwards trend over the 8 intervals  rather than recovering to the same levels (the scaling on the GC graph for THb potentially masks it a bit). Second i am not sure i follow your comment "and that the HHb reduces less each time causing the SmO2 figure to be reduced." To me it looks like HHb increases with each consecutive interval both during the interval and during the recovery which would be consistent with a Sm02 drop.

My interpretation would have been that that this was due to gradually increasing CO2 within the muscle? This would lead to vasodilation (explaining upward THb trend) and reduce the blood's oxygen affinity (so lower Sm02 on peaks and minimum values).

The higher vasodilation might also increase venous return, increasing stroke volume, which then itself also increases THb etc, although this aspect seems less consistent with the Sm02 reactions.

What do you think of this as possible explanation(s)? 


Regards
Ryan

sebo2000

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 #3 
Hi Craig,

I think this is exactly what I would expect to see in any interval session when you are not going by Moxy but power/ HR etc.

I have very similar examples in cycling when I use power and fixed number of reps eg: 10x1min@100% of FTP, instead of using Moxy to determine when to start next rep.

Ryan explained this perfectly: CO2 buildup, if you scale tHb in GC you will see last 4-5 tHb peaks are higher from first 5



CraigMahony

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 #4 
@ryinc and @sebo

Thanks for your input.
Apologies, I was not clear with my explanation. During the intervals the HHB increases. During the recovery the HHB (blue line) does not drop back down, ie recover, as much during the last few intervals. I should have said that HHb recovers less each time.

The recoveries were not fixed time recoveries Sebo. I would have thought that by going by HR that the same level of homeostasis would have been reached during each recovery. I find on my own rides that heart rate matches the recoveries shown by a moxy on a non priority muscle.

From the raw data the tHb peaks after the intervals were 11.99, 12.07, 12.07, 12.06, 12.11, 12.05, 12.05 and 12.06 after which she lay down on the ground. So to me the tHb was fairly consistent with the exception of the 5th recovery. 

After you both suggested that it may be a respiratory issue with CO2 I went and looked at the data again in finer detail. I had originally discounted this as I did not see a delay in SmO2 recovery. Also the rest periods in the last 3 recoveries were between 2:30 - 3:30. I would have thought that for a non maximal work interval of 23 - 24 seconds that 3 minutes would have been sufficient for respiratory recovery. When I rechecked I found that there were very small delays of 2 seconds, a little longer on the first one. There was no delay on the last 3 intervals though. Mind you, the moxy was set on the default of 2 second update with smoothing. On some of the delayed recoveries the tHb had only increased 0.01 - 0.02 before the SmO2 started increasing as well. What is the error rate on the Moxy? There also must be some rounding of figures as well. So given that there were no delays of SmO2 recovery in the last three recoveries, it seems her respiratory system was working better and CO2 should not have been increasing. Why then were there higher HHb levels during recovery? Or do you think there was still CO2 build up at this stage?
ryinc

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 #5 

Hi Craig

Just to be clear, I am not sure our (my) interpretation went so far as to say it was necessarily a respiratory limitation. To demonstrate the difference, consider the start phases of a 5-1-5 we often see effects of vasodilation due to increased presence of C02, even though the respiratory system would not be in "trouble" at this early point in the assessment. 

I note your point about Thb Peaks on recovery, but:

  • I think sometimes “small” THb differences are actually quite large. I have actually started a separate thread about this a day or two ago in the questions and answers section. 
  • Look at the mark-up below. I see a general increasing THb trend, (that actually already starts prior to the 150m intervals), even if the maximums are only very slightly higher as you point out. I realise that these lines are somewhat subjective - just showing you how "i saw" it.

THb trend.jpg  On a side note, what was happening at about 18-20 minutes? That section looks interesting with HHb just steadily rising (but ThB and O2Hb up and down).

CraigMahony

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 #6 
Thanks again ryinc.

At the 18 - 20 min mark the athlete was warming up doing some acceleration strides. These finished at an intensity similar to the 150m reps but were only about 60m in length so the SmO2 did not desaturate as far.

As a side note, this athlete has a very high resting heart rate. Unfortunately, the files from the garmin watch that was worn were deleted so I only had the Moxy files to use.

So if it was a increase in CO2, do you think that it was a respiratory problem or just insufficient recovery time?
ryinc

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 #7 
I am not sure Craig, sorry. The recovery of 2.5 to 3.5 min seems fairly long to me. Also in at least a few of the intervals it looks as though smo2 plateaus and is not going much higher even if you waited (although to be fair in others it seems a further delay might have allowed further rebound)

You say that the athlete lay down after the intervals - was this because they felt they have to i.e. because they felt they had to or was it always part of the plan?

One other different consideration i thought about. Is it possible that the duration of standing still vs walking 50m for each interval changed progressively, and had an influence?
bobbyjobling

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 #8 
It could be a number of things:
  1. Increase of Co2
  2. Decrease of Ph
  3. Increase of muscle temperature
  4. Increase of 2,3 DPG caused by an increase of glycolysis
2,3 DPG is a very important mechanism for hemoglobin to release O2 to the tissue.



CraigMahony

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Posts: 161
 #9 
@ryinc
She did not really need to lie down after the intervals, she just did for about 30 seconds then sat up and changed shoes. As a 100m sprinter she finds this type of work difficult, especially since she has had various intermittent health issues from last August through to March this year so is not as fit as she could be.
You could be correct about the proportion of walking to standing. The next time she does a similar session I intend to get her to walk back to the original start point. This should give a bit better venous return.

@bobbyjobling Thanks for that.
sebo2000

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 #10 
Hi Craig,

When she was lying down was her body completely flat or legs bent? Was each time the same position same place? lying slightly on the downhill (head down) could skew the readings a bit.


CraigMahony

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Posts: 161
 #11 
@sebo

She only laid down at the completion of the main set. Between intervals she walked 50m to the next start point then waited in a standing position for her HR to come down. She will do the same session next week but I will get her to walk back to the original start point and see if that improves venous return and lowers her HHb more during recovery.
CraigMahony

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Posts: 161
 #12 

I thought I would follow up with graphs of a similar session done 11 days later. The main difference was that instead of walking forward 50m to the next start point half way around the bend then waiting for her HR to drop, ie do laps, she walked back to her original starting point each time. The time between the reps was approximated the same, ie 3min+. The reps start at about 33 minutes. Prior to that is all warm up. 

Points to note though, on the original one she had done a session the day before, this she did not. This time during warm up she did not feel that good. She described it her muscles all felt tight and she could not move well. She is often a bit sore but is usually right to go by the finish of the warm up. This time she felt somewhat improved but still not great. As this was considered a low intensity session we went ahead with it anyway but her reps were a little slower than last time. This time you can see from the graph that she desaturated about 25% whereas originally she desaturated about 30%. Her 1st, 6th and 8th reps were her fastest.

Having said all that, you can see that the SmO2, O2Hb and HHb are all quite different. This time the SmO2 peaks higher bewteen reps each time as does the O2Hb. Whereas the HHb drops lower each time during recovery. The slight rise in HHb during recovery was when she stopped her walk back to turn around and say something to me.

So it would seem to me that doing a full walk back reduced her HHb levels as opposed to the 50m walk and rest. She also seemed to get more oxygenated, at least in the VL where the Moxy was. I will try this again when she is feeling as muscularly tight so as to see if it was the  walk back that made the difference or the slightly lowered intensity. I will also do it when she has a similar session the day after a speed session like in the first set of results. 
HayleySmO220170624.jpg 


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