FORGET
THE FAT-BURN ZONE
High Intensity Aerobics Amazingly
Effective
"Fat burn is greater when
exercise intensity is high."
Izumi
Tabata
I believe in high-intensity aerobics.
In Ripped 3, for bodybuilders, I recommended
"a variety of relatively short and infrequent aerobic sessions
interspersed with explosive muscular effort." In Lean
For Life, published six years later, I emphasized
high-intensity aerobics even more; I reduced the
frequency of aerobic sessions to two times a week (in Ripped
3 I recommended up to four) and substantially increased
the intensity. But it wasn't until recently, when my friend Richard
Winett, Ph.D., publisher of Master Trainer,
called my attention to new research findings, that I came to fully
appreciate the superiority of high intensity aerobics compared to the
usual prescription that heart rate be maintained between 60% and 80% of
maximum.
As explained in the nearby FAQ
(Low intensity aerobics?), high intensity aerobics burns the same amount
of fat as low intensity, but the expenditure of calories is
substantially greater; plus, intense aerobics produces
a higher level of fitness. Importantly, the more fit you become, the
more likely you are to use fat as fuel for any given activity. And now,
research in Japan and in Canada shows that short, very intense aerobic
sessions are amazingly effective for both fitness and fat loss.
Maximal oxygen uptake, or V02max, is
generally regarded as the best single measure of aerobic fitness. As the
rate of exercise increases, your body eventually reaches a limit for
oxygen consumption. This limit is the peak of your aerobic capacity, or
your V02max. As intensity increases beyond V02max, your body must shift
to anaerobic (without oxygen) energy production. An oxygen debt begins
to build at this point and blood lactate levels climb. In general terms,
one's ability to continue exercising in the face of rising oxygen
deficit and lactate levels is called anaerobic capacity.
This is important because many
high-intensity sports (including basketball, football, soccer and speed
skating) require a high level of both aerobic and anaerobic fitness.
Clearly, total fitness involves both high V02max and high anaerobic
capacity. A training protocol that develops both would be a godsend.
Izumi Tabata and his colleagues at the
National Institute of Fitness and Sports in Tokyo, Japan, compared the
effects of moderate-intensity endurance and high-intensity intermittent
training on V02max and anaerobic capacity. (Medicine and
Science in Sports and Exercise (1996) 28, 1327-1330).
Interestingly, the high-intensity protocol had been used by major
members of the Japanese Speed Skating team for several years;
it's a real-world training plan. As you will see, however, the protocol
is unique among aerobic training programs for its intensity and brevity.
Many studies have been done on the
effect of training on V02max, but little information has been available
about the effect on anaerobic capacity. That's because until recently
methods for measuring anaerobic capacity have been inadequate. This
study used accumulated oxygen deficit to measure anaerobic energy
release, and is one of the first to measure the effect of training on
both aerobic and anaerobic capacity.
Notice that the duration of the
moderate-intensity and the high-intensity protocols are drastically
different: (excluding warm-ups) one hour
compared to only about 4 minutes per training schedule
Tabata's moderate-intensity protocol
will sound familiar; it's the same steady-state aerobic
training done by many (perhaps most) fitness enthusiasts.
Here are the details (stay with me on
this): In the moderate-intensity group, seven active
young male physical education majors exercised on stationary bicycles 5
days per week for 6 weeks at 70% of V02max, 60 minutes each session.
V02max was measured before and after the training and every week during
the 6 week period. As each subject's V02max improved, exercise intensity
was increased to keep them pedaling at 70% of their actual V02max.
Maximal accumulated oxygen deficit was also measured, before, at 4 weeks
and after the training.
A second group followed a
high-intensity interval program. Seven students, also young and
physically active, exercised five days per week using a training program
similar to the Japanese speed skaters. After a 10-minute warm-up, the
subjects did seven to eight sets of 20 seconds at 170% of V02max, with a
10 second rest between each bout. Pedaling speed was 90-rpm and sets
were terminated when rpms dropped below 85. When subjects could complete
more than 9 sets, exercise intensity was increased by 11 watts. The
training protocol was altered one day per week. On that day, the
students exercised for 30 minutes at 70% of V02max before doing 4 sets
of 20 second intervals at 170% of V02max. This latter session was not
continued to exhaustion. Again, V02max and anaerobic capacity was
determined before, during and after the training.
In some respects the results were no
surprise, but in others they may be ground breaking.
The moderate-intensity endurance training program produced a significant
increase in V02max (about 10%), but had no effect on anaerobic capacity.
The high-intensity intermittent protocol improved V02max by about 14%;
anaerobic capacity increased by a whopping 28%.
Dr. Tabata and his colleagues believe
this is the first study to demonstrate an increase in both aerobic and
anaerobic power. What's more, in an e-mail response to Dick Winett, Dr.
Tabata said, "The fact is that the rate of increase in V02max [14%
for the high-intensity protocol - in only 6 weeks] is one of the highest
ever reported in exercise science." (Note, the students
participating in this study were members of varsity table tennis,
baseball, basketball, soccer and swimming teams and already had
relatively high aerobic capacities.)
The results, of course, confirm the
well-known fact that the results of training are specific. The intensity
in the first protocol (70% of V02max) did not stress anaerobic
components (lactate production and oxygen debt) and, therefore, it was
predictable that anaerobic capacity would be unchanged. On the other
hand, the subjects in the high-intensity group exercised to exhaustion
,and peak blood lactate levels indicated that anaerobic metabolism was
being taxed to the max. So, it was probably also no big surprise that
anaerobic capacity increased quite significantly.
What probably was a surprise, however,
is that a 4 minute training program of very-hard 20 second repeats, in
the words of the researchers, "may be optimal with respect to
improving both the aerobic and the anaerobic energy release
systems." That's something to write home about!
What About
Fat Loss?
Angelo Tremblay, Ph.D., and his
colleagues at the Physical Activities Sciences Laboratory, Laval
University, Quebec, Canada, challenged the common belief among health
professionals that low-intensity, long-duration exercise is the best
program for fat loss. They compared the impact of moderate-intensity
aerobic exercise and high-intensity aerobics on fat loss. (Metabolism
(1994) Volume 43, pp.814-818)
The Canadian scientists divided 27
inactive, healthy, non-obese adults (13 men, 14 women, 18 to 32 years
old) into two groups. They subjected one group to a 20-week endurance
training (ET) program of uninterrupted cycling 4 or 5 times a week for
30 to 45 minutes; the intensity level began at 60% of
heart rate reserve and progressed to 85%. (For a 30-year-old, this would
mean starting at a heart rate of about 136 and progressing to roughly
170 bpm, which is more intense than usually prescribed for weight or fat
loss.)
The other group did a 15-week program
including mainly high-intensity-interval training (HIIT). Much like the
ET group, they began with 30-minute sessions of continuous exercise at
70% of maximum heart rate reserve (remember, they were not accustomed to
exercise), but soon progressed to 10 to 15 bouts of short (15 seconds
progressing to 30 seconds) or 4 to 5 long (60 seconds progressing to 90
seconds) intervals separated by recovery periods allowing heart rate to
return to 120-130 beats per minute. The intensity of the short intervals
was initially fixed at 60% of the maximal work output in 10 seconds, and
that of the long bouts corresponded to 70% of the individual maximum
work output in 90 seconds. Intensity on both was increased 5% every
three weeks.
As you might expect, the total energy
cost of the ET program was substantially greater than the HIIT program.
The researchers calculated that the ET group burned more than twice as
many calories while exercising than the HIIT program. But (surprise,
surprise) skinfold measurements showed that the HIIT group lost more
subcutaneous fat. "Moreover," reported the researchers,
"when the difference in the total energy cost of the program was
taken into account..., the subcutaneous fat loss was ninefold
greater in the HIIT program than in the ET program." In
short, the HIIT group got 9 times more fat-loss benefit for every
calorie burned exercising.
How can that be?
Dr. Tremblay's group took muscle
biopsies and measured muscle enzyme activity to determine why
high-intensity exercise produced so much more fat loss. I'll spare you
the details (they are technical and hard to decipher), but this is their
bottom line: "[Metabolic adaptations resulting
from HIIT] may lead to a better lipid utilization in the postexercise
state and thus contribute to a greater energy and lipid deficit."
In other words, compared to moderate-intensity endurance exercise, high-
intensity intermittent exercise causes more calories and fat to be
burned following the workout. Citing animal studies, they also
said it may be that appetite is suppressed more following intense
intervals. (Neither group was placed on a diet.)
The next time someone pipes up about
the fat-burn zone, ask them if they are familiar with the Tabata and
Tremblay research reports.
[You'll find high-intensity aerobic
workouts for bodybuilding in Ripped 3 and for
balanced fitness, strength and endurance, in Lean For Life;
both books are in the products
section of this site. Routines specifically applying Tabata-type
intervals are explained in chapter 5 of Challenge Yourself.
Keep in mind that VO2max can only be measured in the laboratory; you'll
have to estimate 170% of VO2 max. Don't try to make it too complicated.
Simply chose a pace that brings you near exhaustion on the final
20-second rep; you should become more fatigued with each rep. Increase
the pace as your condition improves. It's always better to underestimate
your ability at the start. Begin a little slower than you think you can
handle, and then adjust the pace from workout to workout. Don't
attempt high-intensity intervals unless you are in good condition;
they're not appropriate for beginners. Note the medical warning
which follows.]
Warning
The Tremblay group and Dr. Tabata, in
his e-mail response to Richard Winett, emphasize this warning:
"High-intensity exercise cannot be prescribed for
individuals at risk for health problems or for obese
people who are not used to exercise."
NOTE: This article was written by
Clarence Bass. Please check out
www.MakesYouFast.com for the latest cutting edge information on how
to benefit from this type of training.
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