From: smay@boi.hp.com (Scott Smay)
Subject: Re: VO2 MAX - Can it be used in planning training?
Date: Mon, 16 Nov 1992 20:24:21 GMT
Organization: Hewlett-Packard / Boise, Idaho
X-Newsreader: TIN [version 1.1.4 PL6]

Julia Collins (jac@noaacrd.colorado.edu) wrote:
: In article <1992Nov13.155049.12840@mlb.semi.harris.com> mvm@epg.harris.com (Matt Mahoney) writes:
: >In article <BxME55.62v@mach1.wlu.ca> sche7135@mach1.wlu.ca (Scott Schelter u) writes:
: >>          I have this nagging question in my mind. I'm wondering what
: >>exactly VO2 max is. My understanding is that it is maximal oxygen
: >>consumption before the body starts to work anaerobically.
: >
: >No, that is called anaerobic threshold.  Your body starts to accumulate
: >lactic acid at 60% to 90% of VO2 max, depending on your fitness level.
: >You cannot maintain a level above anaerobic threshold for more than a
: >few minutes because of muscle fatigue.
: 
: Actually, you can maintain a workload at or above the lactate threshold 
: for longer than a few minutes, depending upon your pain tolerance.
: "Anaerobic threshold" is a misnomer, because there's plenty of O2 around.
: At that level of intensity, though, anaerobic (glycolytic) processes
: are increasingly called into play to provide energy, because the aerobic
: processes can't provide the energy fast enough. Lactate begins to 
: accumulate faster than it can be cleared at this work intensity.
: 
: >VO2 max is your maximum oxygen uptake.  A value of 40 milliliters per
: >kilogram of body weight per minute is typical.  Elite athletes may
: >have a VO2 max of 75-80 ml/kg/minute.  At VO2 max, you will quickly
: >accumulate lactic acid and be forced to slow down after 1 or 2 minutes.
: 
: No, lactate accumulation begins at the lactate ("anaerobic") threshold.

Don't you mean,"yes, although accumulation begins at etc, etc."

: 
: >
: >Both VO2 max and anaerobic threshold can be increased with aerobic
: >exercise near their respective limits.  The reason that anaerobic
: >threshold is not 100% of VO2 max is because the fast twitch muscles
: >(which produce lactic acid) start to fire before all of the slow
: >twitch (oxygen using) fibers fire.
: >
: I think you mean the fast twitch fibers start to fire before all of the
: slow twitch fibers cease firing?  This gives a somewhat inaccurate 
: picture of the process - as if you use one type of fiber, then the
: body switches to another.  In reality, it's a smooth continuum. At no
: time is the body completely "aerobic" or "anaerobic".  But the harder
: the exercise intensity, the more anaerobic glycolysis will be called
: into play, and the greater the lactate accumulation.  Also, both
: types of fibers are able to produce lactate (which is converted to 
: lactic acid).  The fast twitch fibers have very little machinery to 
: perform the energy-producing aerobic oxidation processes, so they tend
: to be best at producing energy via anaerobic glycolysis.  They are also
: the power fibers, and used more as work intensity increases.  Thus
: the connection between [more work] --> [lactate].
:

Both processes, as written, describe a continuous transition between aerobic
and anaerobic processes (ignoring the suggestion that slow twitch fibers
cease firing as exertion intensity increases). Again, I think the attempt
at correction is saying essentially the same thing as the original reply,
i.e., that lactate accumulation rises sharply as fast twitch fibers are
recruited.
recruited. 

Excuse me for posting with no new information or insight, but I am confused
by the second reply which claims to disagree with the first reply, but seems
to corroborate it.

cheers,
scott