Metabolic efficiency testing

DaveyL

http://www.saris.com/athletes/PermaLink ... 39f65.aspx

Interesting piece on the Cycleops website. They can measure the % of fat and carb you are burning as you ramp up through the Watts in a test, efficiency also seems to fall out from it as well as they measure the number of calories being burned as you go.

I guess I would need more info as I didn't really get the bit at the end where they talk about using it to train in specific areas in and around the "crossover point" where you switch from a majority of fat for fuel to carbs for fuel. I guess raising this point to as high a power as possible is a very beneficial thing.

Sounds interesting though - and I think a few folk in the UK offer this. Anyone done one?

Alex_Simmons/RST

Since FFA metabolic process is a wholly aerobic, then the best training to lift the absolute and relative power levels at which you are still utilising a substantial proportion of FFA (and therefore sparing glycogen for when it really counts) is to train to lift you aerobic abilities, i.e. threshold and maximal aerobic power, which ironically involves efforts that are almost entirely fueled by glycogen (but not exclusively at these levels of course). IOW good progressive doses at all levels above recovery will promote this adaptation.

DaveyL

Thanks Alex.

Just wondering if it maybe helps to know quite specifically the power at which cross-over occurs, e.g. for setting zones. Might it be beneficial to make sure you do long steady rides in that zone, and at the upper end of it, to maximise buring of fat, and minimise that ravenous hunger you can get when you come back from a long ride?

I also found it interesting (though it was difficult to see the detail) how the two riders in the videos seemed to differ in just how far (or close in the latter case) their crossover points were in relation to where thay had to abandon the ramp test.

jibberjim

DaveyL wrote:

Just wondering if it maybe helps to know quite specifically the power at which cross-over occurs, e.g. for setting zones. Might it be beneficial to make sure you do long steady rides in that zone, and at the upper end of it, to maximise buring of fat, and minimise that ravenous hunger you can get when you come back from a long ride?

minimising the hunger is best done by EATING whilst on the ride. No point in seriously depleting your glycogen levels then having a big recovery meal when you get home, don't let them get that way in the first place and start refueling even before you run out.

DaveyL

Yes, but I am just wondering if there might be some mileage in knowing where to ride to maximise "fat burning" and minimise glycogen depletion during the ride, if the "crossover" point is somewhere in the zone you would do long rides in.

jibberjim

DaveyL wrote:

Yes, but I am just wondering if there might be some mileage in knowing where to ride to maximise "fat burning" and minimise glycogen depletion during the ride, if the "crossover" point is somewhere in the zone you would do long rides in.

Unlikely, being either side of a crossover point isn't going to make much difference, at the relatively light intensity you're talking about the difference is pretty minor between either side (48% FFA's vs 52% FFA's isn't going to make any material difference) And you won't be able to track changes in the percentages as your fitness changes unless you're endlessly hooked up to a gas exchange monitor.

Also, given that the tests are pretty much always done indoors on a trainer, at a fixed cadence / increasing force situation the fuel usage is likely not going to be identical where you're varying cadence and force much more. Perhaps if you're doing a 100mile TT, but then again, you're going to want to complete it as quickly as possible and not in some way optimise fuel usage.