In Search Of The Ideal
Aerobics Routine
"Six to 8 very hard 20
second intervals with 10 second rest periods may be one of the best
possible training protocols" says Izumi Tabata, Ph.D., National
Institute of Health & Nutrition, Tokyo, Japan
Why does this very short interval
workout ( it is also discussed in article #10, Forget The Fat-Burn Zone)
work so well? Why does this protocol substantially improve both aerobic
and anaerobic capacity? Why is that a surprise? Is there a lesson in
this for bodybuilders and others interested in both strength and
endurance?
Overload and
Specificity
The answers to the first three
questions lie mainly in the principles of overload and specificity. The
overload principle says that training adaptations come about when the
body is subjected to unaccustomed stress. Specificity says the
adaptation depends on the nature of the overload imposed. In other
words, specific exercise overload brings about specific training
effects. For example, strength training induces specific strength
(anaerobic) adaptations and endurance exercise elicits specific
endurance (aerobic) adaptations - with essentially no interchange
between the two types of training. As you'll see, these two principles
explain both why the single protocol was not supposed to cause both
aerobic and anaerobic improvements and, interestingly, why both types of
adaptations did in fact occur.
As a follow-up to the study discussed
in article #10, Forget The Fat-Burn Zone, Dr.Tabata and his colleagues
conducted a second study "to evaluate the magnitude of the stress
on the aerobic and the anaerobic energy release systems" of the
high intensity protocol used in the previous study and, additionally, of
a second interval protocol. (Medicine and Science in Sports
and Exercise (1997) 29, 390-395) The two protocols in the
follow-up study differed in three ways: interval
duration, intensity and rest between bouts.
As in the previous study, young male
members of college varsity teams exercised on stationary bicycles. The
two protocols were given the catchy names 1E1 and 1E2. Protocol 1E1 was
the same as before: following a 10 minute warm-up, each
subject did one set of 6-7 bouts of 20 seconds at approximately 170% of
the subject's maximal oxygen uptake (VO2max), with 10 second rest
periods, to exhaustion. The 1E2 group did 4-5 bouts of 30 seconds at
200% of VO2max, with 2 minute rest periods, to exhaustion. For each
protocol, the criteria for exhaustion was that the subject was unable to
maintain a pedaling speed of 85 rpm. Expired gas was collected
continuously every 10 seconds to measure the oxygen uptake. As in the
earlier study, accumulated oxygen deficit was used to measure anaerobic
energy release.
The results were eye-opening. The 1E1
protocol taxed both aerobic and anaerobic capacity significantly more
than the 1E2 protocol. The peak oxygen uptake during the last 10 seconds
of 1E1 was "not statistically different from the subjects'
VO2max." But the peak oxygen uptake at the end of 1E2 "was
much less than the VO2max." Likewise for anaerobic output:
For 1E1, accumulated oxygen deficit was essentially 100% of the subjects
anaerobic capacity, but for 1E2 it was only 67%. In short, the 20 second
intervals, with 10 seconds rest, overloaded both aerobic capacity and
anaerobic capacity to the max, while the longer and harder interval
protocol, with two minute rest periods, did not. In both respects, the
stress produced by 1E2 fell well short of maximum.
This, of course, is why 1E1 improved
both aerobic and anaerobic fitness. In the words of the researchers,
"For most physical properties the more demanding the training is
the greater the improvement of the property." If you overload
aerobic capacity and anaerobic capacity maximally, you should get
maximum improvement in both capacities.
Yes, this study is good news for the
many athletes engaged in high-intensity sports which demand both aerobic
and anaerobic fitness and those who strive for total fitness. But why
did 1E1 work so much better than 1E2? (The explanation is a little long,
so bear with me.)
First, it has long been known that
intervals are an effective training method. With intervals, more total
work can be accomplished at a given intensity than when exercising
continuously. For example, few people can run a 4 minute mile, but many
more can complete a mile in 4 minutes of actual running, if the distance
is broken into segments or intervals separated by rest periods.
The Surprise
Exercise physiology textbooks tell us
that work interval duration and intensity, and the length of the rest
periods - the variables studied by Dr. Tabata - must be carefully
adjusted to meet the specific requirements for different performances.
As indicated above, adaptations are specific to the speed and duration
of workout. Generally, short hard intervals with long rest periods are
recommended to improve anaerobic capacity; and many sets and repetitions
of longer less intense intervals with short rest periods are suggested
to overload the aerobic system.
In other words, the interval protocols
traditionally prescribed to engage the aerobic system are usually quite
different from those suggested for anaerobic training. This is simply an
application of the specificity principle, with little or no interchange
predicted between the two types of training.
That, of course, is why it was a
surprise when Dr. Tabata's earlier study found that the 1E1 protocol (20
second bouts with 10 seconds rest) "may be optimal with respect to
improving both the aerobic and anaerobic energy release systems."
As readers of my earlier article will remember, Dr. Tabata told Dick
Winett in a personal communication "that the rate of increase in
VO2max [14% in only 6 weeks] is one of the highest ever reported in
exercise science." Recall also that anaerobic capacity increased by
a whopping 28%.
The Key
Factor
Like Goldilocks' porridge, it seems
that Dr. Tabata has come upon an interval protocol that is "just
right." As shown in the follow-up study, 1E1 overloads both aerobic
and anaerobic capacity maximally - with the predictable result that both
systems benefit optimally. As the original research report stated:
"1E1 may be one of the best possible training protocols...."
But why? Why did the 1E1 protocol
stress both aerobic and anaerobic capacity maximally, when the more
intense (200% Vo2max vs. 170%) and longer (30 seconds vs. 20-s) bouts of
the 1E2 protocol did not? The researchers believe the key factor was the
difference in the rest periods.
The relatively long 2 minute rest
periods in 1E2 allowed oxygen uptake to fall considerably and,
therefore, when the next exercise bout started there was a delay before
the oxygen uptake increased and began again to approach maximum. On the
other hand, the short 10 second rest periods in 1E1 allowed only slight
recovery, and therefore oxygen uptake increased in each succeeding bout,
reaching maximum capacity in the final seconds of the last bout. The
same was true for anaerobic energy release. The long rest periods in 1E2
stopped the buildup of lactate and allowed the re-synthesis of
phosphocreatine (see creatine article on this website) to occur. Again,
the short rest periods in 1E1 caused the oxygen deficit to continue
building from rep to rep, reaching maximum anaerobic capacity at the end
of the exercise.
Dr. Tabata's 1E1 protocol may not be
perfect, but he and his colleagues seem to have found a sweet spot where
aerobic and anaerobic capacity peak simultaneously.
The Lesson
It seems to me that the lesson in this
for bodybuilders and other fitness enthusiasts is that more aerobic
training is not necessarily better. Many athletes and coaches believe
that gains in aerobic endurance are proportional to the volume of
training. In fact, noted exercise physiologists Jack H. Wilmore and
David L. Costill, in their text Physiology of Sport and
Exercise (Human Kinetics, 1994), state flatly:
"Because volume is the key to successful aerobic training,
[athletes] must perform a large number of [intervals]." (They do
caution that there's an upper limit.)
Importantly, the two studies by Dr.
Tabata's group strongly suggest that volume is not necessarily the key.
Recall that the moderate-intensity
group in the first study trained 5 days per week at 70% of VO2max, 60
minutes each session, and increased aerobic capacity only 10% and
anaerobic capacity not at all. And in the second study, the 1E2 group
exercised both harder and longer; they did more total
work than the 1E1 group. Clearly, these studies indicate that gains are
not necessarily dependent on volume or total work performed.
If the goal is improved aerobic and
anaerobic capacity, the Tabata research suggests that intensity,
carefully applied to produce maximum overload - not volume - is the key
to success.
At A Price
Progress by this method, of course,
comes at a price. Tabata's 1E1 protocol is physically and
psychologically taxing. It requires considerable motivation. Dr. Tabata,
in a personal communication, warned Dick Winett:
"This protocol [was] invented to stress the cardiovascular systems
of top Japanese [speed] skaters who got medals in the Olympic games.
Therefore, the protocol is very tough. The subjects lay down on the
floor after the training." Tabata wondered how many people would
"feel eager to do this type of exercise."
Still, for those who are fit and
healthy (if you have questions about your health by all means check with
your doctor) and up to the challenge, Tabata offered this encouragement:
"From the theoretical point of view, the higher the oxygen uptake
obtained in a specific training protocol, the higher the improvement of
VO2max."
Good luck.
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