Can GC help me identify LT1?

[Gene Raphaelian]

This may be a stupid question, but that has never stopped me before ;-)

I realize the best way is to conduct a lactate "test" but I'm curious if there is an easier way. So to that end is there a chart or a method by which I can use GC (analyzing power data) to approximate LT1? For those that have done a formal lactate test do you see LT1 occurring at a certain point of MAP?

Thanks in advance for any help or insights you might have.

Best,

gene r 

[Mark Liversedge]

On Thursday, 22 September 2016 19:42:48 UTC+1, Gene Raphaelian wrote:

This may be a stupid question, but that has never stopped me before ;-)

Its a really good question. 

Just so we're using the same terminology:

There are at least 4 types of points in the intensity continuum (in blue above), and a whole collection of measures that are in the same sort of ballpark (in black above). 

To be clear, in the diagram the grouping is not to say each measure is directly equivalent, nor suggest anything about the relative distance between them. It is to highlight the varying intensity indexes and how they are roughly grouped. Indeed, in each individual the relative distances and relationships between all the measures will differ, and crucially, will change with training. And tracking them gives insight into the impact of your training !

So, just to confirm your terminology;

LT1 - is largely equivalent to the point at which lactate rises 1mmol above baseline in a lactate test, which in turn is roughly the same as the GET.

LT2 - is largely equivalent to the point at which lactate rises faster than it can be cleared, roughly the same sort of intensity as CP, MLSS, etc 

Your question was about estimating LT1 (not LT2), so actually, NO, there is no way of doing this with GC*

The reason it is a good question is about how we choose intensities to workout at. Currently we index zones from CP making broad assumptions about the relationships between all the intensity levels. It would be much better if we had estimates for LT1 since its commonly used to delineate between light recovery and moderate intensity (L1, L2). Additionally, being able to track changes to LT1, LT2, Max Aerobic, Max Power in an individual would also give insight into the effects of training. 

So, If anyone has any insight into estimating LT1 with power data (or test protocol using power data) from the literature then we'll implement it in a flash !

Thanks

Mark 

* apols for so much waffle to say no, but this diagram needed explaining to stop folks misinterpreting it

[Ale Martinez]

IIRC from a previous discussion on estimating power @ LT1/VT1 as the boundary between polarized zones I and II we settled on 85%CP, but I don't know if there is a better estimate without measuring lactate or VO2.

[Mark Liversedge]

On Thursday, 22 September 2016 23:21:19 UTC+1, Ale Martinez wrote:

IIRC from a previous discussion on estimating power @ LT1/VT1 as the boundary between polarized zones I and II we settled on 85%CP, but I don't know if there is a better estimate without measuring lactate or VO2.

Yes, exactly. It would be really interesting to be able to estimate it from SMO2, power or HR data ... even if the estimate wasn't wholly accurate it would be fun to watch it change over time and compare and contrast with the PD models.

Mark 

[Stefan]

An estimation from SmO2 was a main selling point when I got a BSX. But then they dropped the estimate. Now they just report 75% FTP. At the time of the change they said this is just temporary. Does not seem they've come any further with this. It seems BSX is more occupied with developing new products. Do the Moxy people make any progress on that?

Looking at the few research papers on SmO2 and Thresholds I can always see this clear breakpoint for LT2. Not sure if it is even possible to extract LT1 from the data.

One of the main problems for a customer: while you can easily validate LT2 with a simple all out test (or at least approximately), this is not feasible with LT1. So there is always a doubt.

Having a proper field test or other method to derive LT1 would be amazing. Especially for the long distance folks out there.

Stefan

[Mark Liversedge]

On Friday, 23 September 2016 11:55:09 UTC+1, Stefan wrote:

An estimation from SmO2 was a main selling point when I got a BSX. But then they dropped the estimate. Now they just report 75% FTP. At the time of the change they said this is just temporary. Does not seem they've come any further with this. It seems BSX is more occupied with developing new products. Do the Moxy people make any progress on that?

Yes, I sent a note to Roger at Moxy yesterday, will update. Agree re: usefulness to long distance folks !

Mark 

[Andrew Seitz]

Do any of the points in your figure correspond with inflection points in the HrPw plot? I can't seem to find the specific page I had previously read (and I haven't yet performed a ramp test to see what my own data looks like) but I do remember reading that during a ramp test to failure there are typically (2) inflection points for the HrPw plot. Do either of those points correspond (even roughly) with any of the points in the figure?

andy