unCoachJasonTM
VO2max
The
monthly newsletter of RunCoachJason.com
Jason
Karp, professional coach, consultant, freelance writer
August,
2005
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In
this issue:
Integrating
Science with Application—Summer Mileage
Lactate
and Fatigue
VO2max
Estimation
In
Press
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Integrating
Science with Application—Summer Mileage
Many
runners, from those in high school getting ready for cross country season to
those getting ready for a fall marathon, use the summer to build an aerobic
base by running lots of miles.
Running
lots of miles increases muscle capillary and mitochondrial densities,
increases red blood cell and hemoglobin concentrations and total blood volume,
increases your muscles’ ability to extract oxygen from the blood, and
enhances your muscles’ ability to store carbohydrate and rely on fat as
fuel.
Research
has shown that runners who perform greater volumes of endurance training tend
to be more economical, which has led to the suggestion among scientists that
running high mileage (>70 miles per
If
you’re going to increase your mileage this summer, increase it slowly (about
5 to 10 miles per week) for a few weeks before backing off at a lower mileage
for one week. This will allow your
legs to adapt to the work you’ve been giving them and prepare them for your
next increase in mileage.
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Lactate
and Fatigue
(excerpted
from Karp, J.R. My Love Affair With Lactate.
Track Coach. 171: 5463-5465,5468, Spring 2005.)
Fatigue
is a difficult thing to pin down. Because
there are so many things happening simultaneously inside muscles when they are
working hard, it is difficult, if not impossible, to determine the exact cause
of fatigue. It’s like trying to
find out what causes cancer. Fatigue,
like cancer, has many different faces. The
fatigue associated with the marathon is not like the fatigue associated with
the 800 meters, any more than breast cancer is like prostate cancer.
Scientific inquiry typically begins with the formation of a hypothesis
and the design of a research study to test that hypothesis.
One of the key attributes of a well-designed study is the controlling
of confounding variables, things that can interfere with the outcome.
It is only when these confounding variables are controlled that a
scientist can determine if the observed outcome is an effect of the treatment
that was given. It is similar to
determining why you ran well or poorly on a given day.
After all, there are many things that influence athletic performance.
Things like the weather, the training program, the athlete’s level of
fatigue, the pacing of the race, the athlete’s degree of anxiety or
nervousness, stress from other areas of the athlete’s life, all could have
influenced the athlete’s performance on Tuesday.
But how does the coach know which is the cause?
Such is the case with determining the cause of fatigue.
From
the time Nobel Prize winners A.V. Hill and Otto Meyerhof discovered in the
1920s that lactic acid is produced during fatiguing muscle contractions in the
absence of oxygen, lactic acid has been the exercising community’s scapegoat
for fatigue. But why?
Why does lactate get all the blame?
There has never been any experimental evidence that has shown a
cause-and-effect relationship between lactate production and fatigue.
While lactate increases dramatically during intense exercise, so do
other metabolites, most notably hydrogen ions, which are considered the major
threat to the muscle’s acid-base balance.
Lactate doesn’t even reveal all of herself unless the exercise uses
anaerobic glycolysis as the predominant metabolic pathway.
So in events like the 100 meters, the marathon, or any of the field
events, speaking about lactate is like speaking about your mistress in the
presence of your wife.
When
anaerobic glycolysis is the predominant energy system being used, hydrogen
ions, like lactate, accumulate in muscles and blood.
However, it is the accumulation of hydrogen ions, which are produced
from the breakdown of ATP during muscle contractions and from other chemical reactions of glycolysis, that decreases
muscle pH, causing metabolic acidosis and, ultimately, fatigue.
But even hydrogen’s role in fatigue has been questioned by some
scientists, who lay the blame on yet other metabolites.
Because of lactate’s concomitant increase with hydrogen ions and the
simple method of measuring her concentration, blood lactate is used by
scientists only as an indirect measure of acidosis. Although
it has been widely accepted by the scientific community for a long time that
lactate is innocuous and is not the cause of fatigue during intense exercise,
lactate still takes the blame and still is regarded by runners as the enemy.
Scientific terminology is, unfortunately, slow to change, and lactate
has been the chief sufferer.
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VO2max Estimation
In
the May newsletter, we talked about how VO2max is measured.
But what if you don’t have access to a lab?
There are a few indirect tests you can use to estimate your VO2max.
Here’s two of them:
Cooper
Test:
Named
for Ken Cooper, one of the pioneers of aerobic exercise.
Run as far as you can in 12 minutes.
The test is usually performed on a track, so you know the exact
distance. You can predict VO2max
(in ml/kg/min) with the equation: VO2max = (35.97 x distance covered in miles)
– 11.29.
3-Minute
Step Test:
A
submax test that predicts VO2max using recovery heart rate following 3 minutes
of stepping exercise. For this
test, you need a 16.25-inch step and a metronome set at a rate of 96 beats per
minute for males (24 steps/min) or 88 beats per minute for females (22
steps/min). Take each step to a
4-beat count, always leading with the same leg: up-up down-down.
After 3 minutes, stop and count your pulse for 15 seconds. Multiply
that number by 4 to get your heart rate (HR) in beats per minute.
You can predict VO2max with the following equations: Males: VO2max =
111.33 – (0.42 x HR at end of test); Females: VO2max = 65.81 – (0.1847 x
HR at end of test).
Many
of you in the running community may be familiar with Jack Daniels’ use of
race performances to estimate what he refers to as VDOT, his performance
equivalent of VO2max (The DOT refers to the dot that is typically placed above
the V in scientific writings to denote that it is measured as a rate of oxygen
consumed per minute). His book, Daniels’
Running Formula, has tables where you can look up your VDOT based on
your time for a recent race.
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In
Press...
Two
of my articles appear in the July/August, 2005 issue of
Midwest Running:
Endorphins,
an essay on the constant search for but fleeting experience with endorphins
while running.
Chin-Ups,
Push-Ups, and Hills, an essay on the
lessons about relative strength learned from training for my junior high
chin-up record.
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view past newsletters, go to http://www.runcoachjason.com/newsletter
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©2005
Jason Karp.
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