From: apas614@chpc.utexas.edu (Andy Heekin)
Subject: Re: Aerobic Capacity
Summary: better definition of AT, a VO2 max data point
Organization: The University of Texas System CHPC
Date: Fri, 8 Jan 93 17:43:20 GMT

In article <C0JFDo.MF8@watserv1.uwaterloo.ca>, praetzel@marconi.uwaterloo.ca (Eric Praetzel) writes:
> Round 2:
> 
> In article <1993Jan8.012411.24566@nosc.mil> derion@VAX309.NOSC.MIL writes:
> >In article <C0I7J4.7pn@watserv1.uwaterloo.ca>, praetzel@sunee.uwaterloo.ca (Eric Praetzel) writes:
> >>  I have gotten data from people who had no such deflection point.
> >>I propose a standard.  Ie your "AT" is defined as what you can sustain for
> >>1 hour.  
> >
> >Anaerobic threshold is simply the point at which the relationship between
> >V'E (ventilation) and V'O2 deviates from linearity.  It couldn't be


   I'm not sure what the best definition of AT should be, but in the
   exercise physiology literature it is usually defined as the workload
   at which the blood lactate concentration reaches 4mmol.  This does not
   always coincide with the break in the VE - VO2 curve mentioned above.


   Incidentally, the  ventilation threshold isn't completely due to lactate
   accumulation in the blood.  There are people who lack the enzyme to convet
   pyruvate into lactate so they cannot make lactic acid.  they are called
   McArdle's patients.  Yet they show a typical ventilation threshold like
   everyone else.  Makes you wonder what all is really going on.  Obviously
   it is quite complex.

>   Pretty well every chart I have seen shows a break in the plot.  It is
> usually going from one slope to a higher slope.  The AT tends to be at about
> 75% to 90% of V'O2 max while the VT (ventricle threshold) that you mention
> is at about 60% of V'O2 max.
> 
> >Your measure of "fitness" is the ratio of your V'O2 at the AT and
> >>your V' O2 max.
> > 
> >V'O2 max will increase with training, and you will reach your
> >anaerobic threshold at a higher % of your max with training.
> >I'm not sure what that ratio would tell you.


    It might tell you whether you need to do more hard interval work if
    your AT is at a low percentage of your maximum VO2.


>   Some people will be able to shift their AT point higher up the V'O2 vs
> power curve but generally the heart rate at the AT seems to decrease with
> increases in fitness.  Since people vary so wildly in the AT as a percentag
> of VO2 max I am hopefull that a ratio of the two would give a better indicator
> of how "trained" a person is.
> 
> 
> >> A high V'O2 max guarantees you nothing. 
> >


    I agree.  All things being equal it IS better to have a higher VO2 max.
    But it is a poor predictor of performance.  It can tell you what your
    potential is.  My max is 4.7 liters/min.  It hasn't changed in 8 years.
    I will never be able to cycle at 5.0 liters/min which some people can.
    My AT was 69% of my max about 3 years ago.  I could still cycle at 86%
    percent of my max for an hour.  Last year I rode at a heart rate of
    170 bpm for an hour.  My max is 175 bpm.  Therefore, I must have been
    riding in the neighborhood of 95-96% of my max VO2.  Obviously my AT
    has gone up or something has happened.  I plan to get tested again this
    year.   Over the past eight years I have gradually improved my 40K time
    about 20 minutes.  Much of it is due to better equipment and bike 
    position, but not all of it, as I still improved during periods where
    nothing changed but my training habits.  But everyone IS different.
    My efficency was poor ( < 18% ), I have over 71% fast twitch muscle
    in my quadriceps, mediocre capillary density, etc - so maybe I had more
    room for improvement than the average person.

    The other area of importance is mechanical/metabolic efficiency as
    mentioned earlier in this thread.  Thats how low VO2 max athletes
    get away with great performances.  I personally think that is the area
    to concentrate on as it is difficult to get physiologic adaptations
    to occur after a certain point.
> 
> >> You may be interested to know that my V'O2 max does not change between the
> >>summer (and my height (?) of fitness) and january.  Perhaps this can be
> >
> >It most certainly can change with training!!!  Improvements in V'O2
> >max usually range from 6-20% depending upon initial fitness level.
>   Yes it can.  Some people can keep increasing theirs for 3 or 4 years.  But
> when I consider that I will need a 30% improvment to keep up with my friends
> I am not hopefull because I see no changes over 5,000 km of training.  Each
> person is different.  Recent studies have shown that some people respond
> amazingly to training while others do not. Unfortunately I have not found
> paper copies of those beause I am curious to see what sort of people they
> used.
>   After looking at a bunch of data I am of the opinion that a fit person
> could do a summer of training and have a good idea of what calibre he is.  In
> my case I have seen no improvements even compared to my first year which had
> only 1,500 km of riding (compared to 10,000 km this year).  Yes there are large
> differences in endurance but for the 15 km TT (our clubs short course, out and
> back on flat sheltered ground) I can't see anything.  As encouragement all that
> I can say is if you have it you will keep it. I get my ass kicked weekly by
> 50 year olds that are still doing 40km in 57 min to my 1-07.
>                                            If anyone has hard V'O2
> data I would love to see it.  I am esp. interested in good caliber riders.
>   - Eric 

    - Andy Heekin, UT Austin