From: jac@noaacrd.colorado.edu (Julia Collins)
Subject: Re: VO2 MAX - Can it be used in planning training?
Organization: NOAA Climate Research Division
Date: Mon, 16 Nov 1992 16:16:49 GMT

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.

>
>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].

To answer the original question, your VO2max isn't good for much except
helping you to estimate your lactate threshold (as mentioned above,
usually 65% - 85% (or higher) of VO2max, depending on training level).  
If you know your max heart rate is 190, then estimate a threshold range 
(say, 75% of max, or 143 bpm). Interval workouts should get your heart rate
above this threshold value.  Tempo runs or rides should be done at this
threshold heart rate.

Julia
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