June 2003
THE
CrossFit Journal
IN THIS ISSUE:
Metabolic Conditioning - page 1
Interval Generator - page 5
"mess you up"
Pukie s Glossary of Metabolic Conditioning - page 6
Introduction
In the second issue of CrossFit Journal,  What is Fitness? we explored the nature of metabolic conditioning, or
 cardio , and highlighted some of the qualities of and distinctions between aerobic and anaerobic exercise, and
touched on interval training.
In this issue we ll reexamine metabolic and interval training in a little more detail.
Review
Let s begin with a review of metabolic training. Metabolic training refers to conditioning exercises intended to increase
the storage and delivery of energy for any activity.
There are three distinct biochemical means by which energy is provided for all human action. These  metabolic
engines are known as the phosphagen pathway, the glycolytic pathway, and the oxidative pathway.
The first, the phosphagen pathway, provides the bulk of energy used in highest-powered activities, those that last less
than ten seconds.
The second, the glycolytic pathway, dominates moderate-powered activities, those that last up to several minutes.
The third, the oxidative pathway provides energy for low-powered activities, those that last in excess of several
minutes.
You may recall that the first two pathways, the
phosphagen and glycolytic, delivering energy for 100
high and moderate powered activities, are known
collectively as  anaerobic whereas the third
pathway, the oxidative is known as  aerobic. The
significance of the term  anaerobic lies in the fact
that the phosphagen and glycolytic systems generate
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energy without benefit of oxygen where the oxidative
or  aerobic pathway requires oxygen for energy
production.
The subject of metabolic pathways and energy
production for human activity is known as
 bioenergetics and is loaded with details from
0
biochemistry and discussions of ATP, ADP, substrates,
0 60 130
reaction mechanisms, Krebs cycle and a lot of other
Time (seconds)
stuff that you tried, and probably succeeded, to avoid
learning in high school or college biology.
Phosphagen
Glycolytic
Oxidative
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Percent of total energy
June 2003
If you feel the compulsion to learn more on the biochemistry of bioenergetics here are two convenient starting points:
The N.S.C.A. s Essentials of Strength and Conditioning, an authoritative reference, has a chapter on bioenergetics by
Mike Conley with many of the gory details.
And, from the University of Connecticut here is a brief summary of bioenergetics.
Anaerobics and Aerobics Made Simple
Our purpose in this issue of CrossFit Journal is to avoid the complexities and nuances of molecular biochemistry and
render a useable foundation for understanding  cardio and specifically the CrossFit approach to conditioning.
To that end we will forgo considerations other that the sustainability of maximum efforts and, so, concern ourselves with
all out efforts of varying durations and ignore issues of power, pathways, and energy production.
We only need to remember that anaerobic exercise is metabolically unsustainable exercise whereas aerobic exercise is
sustainable. Sustainability is the key.
Generally, all out efforts of two minutes or less are anaerobic while efforts lasting more than several minutes are
aerobic.
Reducing the whole of bioenergetics to this level isn t just convenient it allows for examination at a level of granularity
that allows for maximum useful understanding of metabolic conditioning. Biochemists, while able to recite intricacies
of energy substrates and ATP production are all too often blind to the interplay of varying exercise protocols and their
resulting fitness.
A metaphor may aid in understanding our position on the science of bioenergetics. We are striving to give you a racecar
driver s sense of auto racing not a mechanical engineer s. Both have their place but only one drives the car on race
day.
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Anaerobic efforts are relatively high powered, and aerobic efforts are relatively low powered. This should be self
evident from our understanding that anaerobic work is unsustainable past several minutes. It would be hard to escape
the observation that power, or intensity, and duration of effort are inversely related. One hundred meter dash pace is a
considerably faster pace than a mile pace.
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June 2003
Aerobic exercise is nearly universally regarded as being heart protective, but there is compelling evidence that shows
that anaerobic exercise is at least as heart protective as aerobic exercise.
Though aerobic exercise is widely recognized as being the ideal vehicle for fat loss, recent studies have shown that
anaerobic exercise is a vastly superior protocol for fat burning.
Anaerobic exercise builds muscle; aerobic exercise burns muscle - period. On this point there is no intelligent debate.
Compare the look of sprinters to long distance runners  here a picture is indeed worth a thousand words.
The muscle wasting nature of aerobic exercise is both cause and symptom of the deleterious effect that endurance
work can have on anaerobic performance. Sadly, this lesson has been slow to spread to many anaerobic sports. It is still
common to find boxers and other martial artists who think that long slow endurance work  roadwork  is essential to
their fight endurance. Nothing could be further from the truth.
On the other hand anaerobic training is of enormous benefit to endurance athletes. Not only does it support and build
muscle, but it gives the  kick needed to win close races. Importantly, not only does anaerobic work benefit aerobic
performance, but anaerobic training can be used to develop high levels of aerobic fitness without the usual muscle
wasting. This is accomplished through interval training and is an integral part of sports training for most sports.
Interval Training
Interval training alternates bouts of high intensity work with rest in repeated timed intervals. The general idea is to
perform a high volume of high intensity work in a limited time. Ultimately, it is nothing more than anaerobic training
with controlled rest periods.
The benefits of interval training are to both anaerobic and aerobic systems. The obvious question is how much benefit
and to which system?
We can orchestrate intervals so that they predominantly stress either aerobic or anaerobic systems. The table below
gives interval strategies to target desired metabolic systems.
Sprint -
i E Phophagen Glycolytic Oxidative
10 - 30 30 - 120 120 - 300
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30 - 90 60 - 240 120 - 300
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1 : 3 1 : 2 1 : 1
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25 - 30 10 - 20 3 - 5
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June 2003
But, even more interesting is the prospect of a
hybrid interval that would greatly stress and thereby
Exerpt from NSCA s Essentials of
substantially condition both anaerobic and aerobic
systems simultaneously. Finding such an interval and
Strength Training and Conditioning
demonstrating its dual potency would be a great find.
Thomas R. Baechle - Editor
It may have been done.
Chapter 5 Bioenergetics - pages 78, 79
Some authors have suggested that aerobic training
Tabata Interval
should be added to the training of  anaerobic athletes
Dr. Izumi Tabata experimented with intervals and
(a process that can be termed combination training)
published in the journal Medicine in Sports and Exercise
to enhance recovery (101) because recovery primarily
the results of an experiment in which he produced
relies on aerobic mechanisms. However, aerobic train-
excellent improvements in anaerobic and aerobic
ing may reduce anaerobic performance capabilities,
conditioning in a group of accomplished athletes with
particularly high-strength, high-power performance
a four minute (3:50) protocol of 20 seconds of all out
(52). Aerobic training has been shown to reduce an-
work followed by 10 seconds of rest repeated 8 times.
aerobic energy production capabilities in rats (128).
Additionally, combined anaerobic and aerobic training
Significantly, Dr. Tabata s 4 minute high intensity
can reduce the gain in muscle girth (24), maximum
group got better V02 max improvement than the control
strength (24, 46, 52), and especially speed-and power-
group, which followed a 60 minute moderate intensity
related performance (28), although the exact mecha-
regimen.
nism is not known (114). It does not appear that the
opposite holds true; some studies and reviews suggest
Clarence Bass , and Peak Performance both give great
that anaerobic training (strength training) can improve
accounts of Dr. Tabata s research and understand the
low intensity exercise endurance (53, 54, 114). Al-
important implications.
though oxidative metabolism is important in recovery
from heavy anaerobic exercise (e.g., weight training,
sprint training) (12, 109) care must be used in prescrib-
Tabata Applications
ing aerobic training for anaerobic sports. In this con-
Dr. Tabata s research subjects exercised on stationery text it should be noted that specific anaerobic training
bikes; we decided to test other applications. can stimulate increases in aerobic power and enhance
markers of recovery (114, 116, 129). Thus, extensive
Our favorite and most effective application has been aerobic training to enhance recovery from anaerobic
the  Tabata squat  a 20 seconds on, 10 seconds off events is not necessary and may be counterproductive
repeated 8 times squatting effort scored by the lowest in most strength and power sports.
number of reps performed in any of the eight intervals.
This single drill tests for and develops elite athletic
capacities. Rankings for this drill accurately predict
ranking performance on a wide variety of fundamental
athletic skills and performance.
Don t
Another of our crew s favored applications is to use the
hold
Tabata interval in a workout where an athlete moves
your
from the Concept II Rower to squats then pull-ups, sit-
breath
ups, and push-ups. Each exercise is performed like the during
anaerobic
Tabata squat  20 on/10 off X 8. Adding the weakest
efforts!
link from each exercise tabulates a final score. The
Rowing is scored in  calories and the other events by
reps. We allow a minute s break between exercises.
Both of these simple workouts are very demanding and
surprisingly potent. Trying either will convince you of
their potency. Our experience is that improvements in
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June 2003
scores for both Tabata workouts suggest strongly that
an athlete is likely to show substantial improvements
wherever we test them.
Interval Generator
Try the Tabata workouts, experiment with varying
interval design, and repeat noticeably difficult protocols
There are no bad intervals, only weak efforts. Variety and
from time to time. Trust that particularly challenging
intensity will ultimately determine preparedness. Here is a
efforts speak directly to your opportunities for physical
scheme to give variance to your anaerobic work.
gains, and that improved performance in those efforts
is the best measure of those gains. Chase the toughest
Intervals generated by this experiment will certainly be
anaerobic yet are certain to pack a substantial aerobic
intervals.
punch.
The most important point to remember is that high
Play with these intervals before or after your regular
intensity efforts can produce dramatic aerobic benefit
workouts or on  rest days.
without the muscle wasting seen with endurance
training.
Dr. Stephen Seiler on Intervals and
Endurace Work
Dr. Seiler is a renowned exercise physiologist and
rowing coach. In a piece entitled  Understanding
Intervals Dr. Seiler explains that there are winning
rowing programs that train all intervals as well as
those that do some, and programs that do none. Each
approach has been shown to produce winners.
Dr. Seiler has concerns about the wisdom of programs
that do too much interval work only because intervals
may produce what he calls first and second wave
adaptation to endurance training but not third wave
Roll single die (or three dice) and for first roll multiply
adaptations. Third wave adaptations are largely
number by 10 for work interval.
specific to the training modality, and have nothing to do
with aerobic conditioning but endurance performance.
Then roll second die and multiply by 5 for the rest
The difference is critical. But do we want third wave
interval.
adaptations?
Roll again and multiply by 2 total for number of
intervals.
Third wave gains in endurance performance are
entirely specific to that sport and have training effects
disadvantageous to much of other sport performance.
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Dr. Seiler s admission that elite aerobic performance
Number
can be trained by high intensity intervals and his
Work Rest of Intervals
concerns that intervals don t produce third wave
2
5
10
adaptations form a terrific rationale for avoiding steady 1
4
state aerobic work. 10
20
2
6
15
30
3
The idea that later adaptations to endurance work are
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20
40
4
highly specific to the training modality and portend
10
25
50
5
little impetus to further cardiovascular development
12
30
60
6
hints at the possibilities for generating additional
cardiovascular benefit by means of shifting training
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June 2003
modalities sufficiently to avoid  third wave adaptations
and focus instead on 1st and 2nd wave adaptations
Pukie s Glossary of Metabolic Conditioning:
from a multitude of protocols and modalities. Our hope
and suspicion is that this broadens the cardiovascular
stimulus.
CrossFit Position
As ridiculous as the idea that extended endurance efforts
optimally confer cardiovascular and fitness benefits is
the notion that a stressor like a bike is good  cardio
whereas a Kettlebell, obstacle course, or CrossFit-like
workout performed at similar exertion levels carries a
lesser cardiovascular benefit! I want to help with some of the basic terminology of
metabolic conditioning, so here s Pukie s guide to easy
bioenergetics complete with commentary
Ultimately the CrossFit position on metabolic
- Pukie
conditioning, or  cardio , is summed in two points:
V02 max:
" Anaerobic training can match endurance training
Maximum amount of oxygen that can be used continuously
for aerobic benefit.
divided by body mass. Long the gold standard of aerobic
" Metabolic training with varying and mixed
fitness, the slight advantage that endurance athletes have
exercise modalities avoids specificity of
over anaerobic athletes in V02 max can be attributable to
adaptation allowing for additional first wave the low body mass of endurance athletes. I can use a similar
definition of strength  by dividing lifts by weight - to show that
 cardiovascular/respiratory adaptations, and
little guys are stronger than big guys.
increased functional strength.
Aerobic:
The clincher is that CrossFit athletes have demonstrated
Low powered, low intensity, long duration  more than several
minutes. This is the easy stuff. Introduced to real efforts these
improved endurance performance without endurance
guys crumble!
training, and even more amazingly, in clinical trials
CrossFit s high intensity regimen has produced
Anaerobic:
improvements in endurance measures that rivaled
Higher-powered, higher intensity, shorter duration efforts
those achieved through programs comprised largely of those less than several minutes. Anaerobic is Greek for  worth
while. Pukie wants to know why there are 1 million recreational
endurance efforts.
traiathletes but only 7 recreational 800 meter athletes.
Police training programs in Florida have found that
Lactate Threshold:
CrossFit produced better distance run times than prior
The point as work intensity increases where lactic acid levels
in the blood rise faster than can be controlled. Lactic acid is a
programs comprised largely of distance runs.
waste product of anaerobic work. Also known as  anaerobic
threshold , the lactate threshold marks the point in intensity
CrossFit athletes live in a steady state of physical
where work has become largely anaerobic. This is also the
preparedness that leaves them primed for specialized
 pussy rest-stop .
training and unknown physical challenges regardless of
Interval training:
whether the demands are aerobic, anaerobic, or both.
Exercise protocol of set periods of high intensity rest and
work. This is how anaerobic athletes develop tremendous
There are cars that get 100 miles to the gallon. They are
levels of aerobic fitness  through intervals. I want to meet
low powered, slow, and fuel-efficient. Others cars are
the scientist who invented this. How else could you do high
intensity work?
high powered and fast while being less fuel-efficient.
CrossFit is building powerful fast athletes not slow, low
Heart rate monitor:
powered, fuel-efficient athletes.
It s all about the performance. Forget heart rate. The heart
rate monitor is a fun toy, though. Mix dehydration, beer, steep
Athletes that train predominantly anaerobic pathways in hill, bicycle, hot humid day and see who can get the highest
number. I ve seen seven people over 200 at once on the same
a wide range of intervals and modalities have at least the
hill. What can you and your friends do?
cardiovascular or aerobic fitness of endurance athletes.
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June 2003
References - NSCA s Essentials of Strength Training and Conditioning
12. Brooks, G.A., and T.D. Fahey, Exercise Physiology; Human Bioenergetics and Its Applications. New York: Wiley. 1984.
24. Craig, B.W., J. Lucas, R. Pohlman, and H. Stelling. The effects of running, weightlifting and a combination of both on growth hormone release.
J. Appl. Sport Sci. Res. 5(4):198-203. 1991.
28. Dudley, G.A., and R. Djamil. Incompatability of endurance- and strength-training modes of exercise. J.Appl. Physiol. 59(5):1446-1451. 1985.
46. Hadmann, R. The available glycogen in man and the connection between rate of oxygen intake and carbohydrate usage. Acta Physiol. Scand.
40:305-330. 1957.
52. Hickson, R.C. Interference of strength development by simultaneously training for strength and endurance. Eur. J. Appl. Physiol. 215:255-263.
1980.
53. Hickson, R.C., B.A. Dvorak, E.M. Gorostiaga, T.T. Kurowski, and C. Foster. Potential for strength and endurance training to amplify
endurance
performance. J. Appl. Physiol. 65(5):2285-2290. 1988.
54. Hickson, R.C., M.A. Rosenkoetter, and M.M. Brown. Strength training effects on aerobic power and short-term endurance. Med. Sci. Sports
Exerc. 12:336-339. 1980.
101. Plisk, S.S. Anaerobic metabolic conditioning: A brief review of theory, strategy and practical application. J. Appl. Sport Sci. Res. 5(1):22-34
. 1991.
109. Scala, D., J. McMillan, D. Blessing, R. Rozenek, and M.H. Stone. Metabolic cost of a preparatory phase of training in weightlifting: A
preactical observation. J. Appl. Sport Sci. Res. 1(3):48-52.1987.
114. Stone, M.H., S.J. Fleck, W.J. Kraemer, and N.T. Triplet. Health and performance related adaptations to resistive training. Sports Med.
11(4):210-231. 1991.
116. Stone, M.H., K. Peirce, R. Godsen, D. Wilson, D.Blessing, R. Rozenek, and J. Chromiak. Heart rate and lactate levels during weight training
in trained and untrained men. Phys. Sportsmed. 15(5):97-105. 1987.
128. Vihko, V., A. Salmons, and J. Rontumaki. Oxidative and lysomal capacity in skeletal muscle. Acta Physiol. Scand. 104:74-81. 1978.
129. Warren, B.J., M.H. Stone, J.T. Kearney, S.J. Fleck, G.D. Wilson, and W.J. Kraemer. The effects of short-term overwork on performance
measures and blood metabolites in elite junior weightlifters. Int,J.SportsMed. 13(5):372-376. 1992.
Editor-In-Chief Editorial Director
Greg Glassman Lauren Glassman
Design
Art Director Lauren Glassman
Photography
Chief Photographer Greg Glassman
Picture Editor Lauren Glassman
Technical Advisors
Derek Wray
Danny John
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