| You’re
familiar with the concept of cardiovascular conditioning, or
aerobics. Unless you’ve landed on this planet within the last
2 minutes, you know about strength training, muscle building,
weight lifting, resistance training, pumping iron and every
other term referring to anaerobic exercise.
Have you heard of metabolic conditioning? Actually, the
term “metabolic” describes two biochemical processes – anabolism,
which is the buildup of substances, and catabolism, the breakdown
of substances. Metabolic conditioning, therefore, is efficiency
in building up and breaking down, or generating the energy necessary
for muscle contraction
Relative to your exercise program, keep in mind: aerobic
training, anaerobic training, and metabolic conditioning. We’ll
see how these correlate.
In 1985, a couple of research findings reported in the newspaper
claimed that what was then termed “Nautilus training” did not
improve aerobic conditioning. The researchers indicated that
a rapid succession of strength exercises on a circuit of machines
elevated and sustained heart rate in the aerobic target zone,
but the training did not meet the requirement for oxygen uptake
– commonly referred to as VO2 max. This oxygen requirement was
established by the American College of Sports Medicine. I had
the opportunity to present an article disputing the VO2 max
requirement to the exercise physiologist most responsible for
the ACSM guidelines.
Another Ph.D-level physiologist, who had a much deeper understanding
of strength training than did the ACSM guideline writer, provided
the word-picture to make this easy to understand.
Imagine that your blood cells are box cars on a train, each
car loaded with packages of oxygen. During steady state, aerobic,
activity, this train circulates throughout your body unloading
oxygen at every working muscle. During strength training, where
the force of contraction creates intra-muscular compression,
the oxygen is unable to enter the working muscle. This is why
the activity is called anaerobic, meaning without oxygen, versus
aerobic, meaning with oxygen.
During strength training, the train circulates your body
the same as it would if the exercise was a bout of aerobics.
Were the contraction not so powerful, the oxygen could unload;
it would enter the working muscle. The cardiovascular system
is functioning, despite the oxygen’s inability to penetrate
the muscle cells. No, say aerobics advocates, there is the issue
of "pressor response," which is the amount of oxygen
delivered per heart beat. It has been determined that strength
training that elevates your heart rate to a specified level
will have a VO2 max that is about 15-25 percent lower than an
aerobic activity that achieves the same heart rate. Aerobics
advocates believe that because oxygen does not get into the
working muscle -- for whatever reason -- the training effect
is different.
My theory?
Exercise physiologists wrote the guidelines of 20 years
ago without understanding circuit strength training. Their guideline
on aerobic training effect had to include an indicator in addition
to elevated heart rate because things such as caffeine, stress
and fright can also quicken your heart. Physiologists, many
of whom were runners, were familiar with VO2 max, so they slapped
that requirement onto the guideline, I suspect.
I say the difference is a matter of open or closed doors
at the working muscle depots. The cardio system is being conditioned
during both types of exercise.
Rather than separating the aerobic and anaerobic metabolic
pathways, it is likely that many activities are a blend of the
two. I know of at least one study that shows
transition from one energy
system to another is gradual. The aerobic pathway has
greater energy production capacity, but the rate at which it
can produce energy is not fast enough to meet the demands of
forceful muscular contraction. Lactic acid, by the way, is not
a waste product. Lactate is a valuable energy substrate that
is oxidized by Type I fibers, heart muscle, the kidney, liver,
and brain.
As you get into better metabolic condition, you will notice
that you are able to start the next exercise as soon as you
can get to the next machine. The time to complete your workout
should decrease, unless you add more exercises. You will be
performing more work per unit of time.
A landmark study at the U.S. Military Academy at West Point
in 1975 showed cadets improving strength almost 60 percent in
just 17 workouts, and decreasing the average time of that workout
by approximately 25 percent.
Metabolic conditioning is more like basketball or hockey,
successions of maximal exertion with only little rest in-between.
Football, with approximately 7 seconds of all-out effort followed
by 30 seconds in the huddle, requires anaerobic conditioning;
unless, of course, one team is using a no-huddle offense.
Metabolic conditioning could give some teams a valuable
edge. For those of us not banging heads on the gridiron, the
by-products of metabolic fitness – according to research --
are improved lipid profile, greater glucose tolerance and insulin
sensitivity, reduced fasting serum insulin levels, lower blood
pressure, and decreased blood platelet aggregation.
These factors make metabolic conditioning an antidote to
hypertension, type II diabetes mellitus, hyperlipidemia, and
obesity.
Keep in mind that metabolic training requires minimal time
(no more than one minute, for sure and not more than 30 seconds
preferably) between
the last rep of one exercise and the first rep of the next.
It also presumes that each set is carried to volitional fatigue,
meaning another repetition in good form would not be possible.
Metabolic conditioning enables you to generate muscle fatigue
throughout your body in rapid succession. It’s something more
than aerobics, however, because I don’t believe a world class
distance runner could perform such a workout without previous
metabolic training. He or she might be able to run forever,
but give them rapid-fire strength exercises and they’ll peter
out. The energy production system is different.
I should also make it clear that I’m also in favor of traditional
aerobic training. To achieve aerobic benefit, you need “sustained
elevated heart rate training” at least three if not five times
per week. Circuit strength training should be conducted no more
than three times per week, preferably only twice after six months
of consistent training. So, another two or three times per week,
bouts of pure aerobics are helpful in achieving a well-rounded
fitness level. |