Wednesday, December 19, 2007

Racing not always the best training...

It's been my personal belief for some time that for time trials, which means FTP, that you need to ride long periods of time at your lactate threshold and/or VO2MAX. Not just short intervals, but lonnnggg ones....

Dr. Coggan commented on a related topic to this in wattage today (thread here), providing a summary of what muscle recruitment you need and the required adaptations.

> And if all of those logical jumps are correct, then the implication
> is that in a time trial, you are recruiting all of your type 1 and
> type 2 fibers.

As a percentage of VO2max, maximal lactate steady state/critical power/
functional threshold power occurs at the point at which, based on
various measurements (e.g., PAS staining of muscle samples, EMG
measurements), significant recruitment of the most fatigable type II
fibers begins (I'd refer to them as type IIb/IIx, but after training
they are converted to type IIa, even if they still remain part of that
final "pool" that is hardest to recruit/most fatigable).

> So if your type 2 fibers fatigue quickly, it will hurt your muscle
> endurance for time trialing, and your ability to jump out of a corner
> 40 times. So that fits both of our profiles, as described above.
> So what governs fatigue resistance of type 2 fibers?
> What sort of training stress is required to improve it?
> I have no clue about the physiology.

I do. ;-)

The factors that govern fatigue resistance in type II fibers are the
same as in type I fibers, as are the mechanisms by which said fibers
adapt to increased use so as to minimize fatigue resistance. These
include, although are not necessarily limited to, an increased ability
to generate energy aerobically (e.g., increased mitochondria,
increased capillarization), as well as a reduction in ATP demand (by
replacing faster type IIx myosin with slower type IIa). Either way,
the way to go about inducing these adaptations is to continuously
recruit these motor units for a sufficient duration so as to induce
the above adaptations, something that can be accomplished numerous
ways (e.g., "aerobic" intervals, long rides). What I would
*hypothesize* is of limited benefit (because the motor units aren't
"switched on" long enough), at least by comparison, would be - ta da!
- criterium racing (or really any group ride that is too short to
force extensive recruitment of type II motor units, due to fatigue of
the primarily-recruited type I motor units). IOW, I believe that
racing is *not* always the best training...

Andy Coggan
My improved FTP over the summer was (IMHO) a result of doing lots of short, hard, time trials. E.g. the Ryder 8k TT (with about 60m of climbing..) 11-12 minutes in VO2Max. I was able to take more than 30 seconds off both the Ryder 8K TT and VeloVets 10k TT times by the end of the summer.