Interval training is a
method of training where you increase and decrease the intensity of your
workout between aerobic and anaerobic training. The protocol for interval
training is to push your body past the aerobic threshold for a few moments and
then return to your aerobic conditioning level with the objective of improving
your performance (speed, strength, and endurance). The aerobic threshold is the
intensity where your body switches from burning a greater percentage of fat to
a greater percentage of carbohydrate and is generally 85% of your maximum heart
rate (train below 85% and it's aerobic; train above
85% and it's anaerobic). Anaerobic exercise is where the body is exercising at
such a rate that the blood stream cannot supply oxygen to muscles fast enough.
Anaerobic exercise is essentially exercise without
oxygen. This happens during high intensity and cannot be held for long periods
of time. A product of your muscle exercising in an oxygen deprived environment
is large amounts of lactic acid. Lactic acid begins building up inside the
muscle at a rate faster than it can be cleared creating muscle failure. Anaerobic exercise refers to anaerobic muscle respiration
and not respiration as a whole. The muscle still receives oxygen, just an
insufficient supply to meet the demands of the activity. During the recovery phase the heart
and lungs work together to "pay back" this oxygen debt and break down
the lactic acid. It is in this phase that the aerobic system is in control,
using oxygen to convert stored carbohydrates into energy.
The premise of interval training is
simple. When you vary your effort by mixing periods of high
and low intensities during your workout, your fitness will improve faster and
more dramatically. During your session, you’ll alternate between high-intensity
intervals and lower-intensity recovery periods. You'll know when you’ve reached
an anaerobic intensity because you'll start feeling a burn in your working
muscles. Remember, the point is to push yourself just beyond your comfort level, but not to
the point of complete exhaustion or injury. This
repetitive form of training leads to the body's ability to adjust to increased
or decreased physical demands. It is also one way we learn to coordinate muscle
movement. Additionally, it makes an athlete very efficient and allows him to
expend less energy doing the same movements. The body begins to build new
capillaries, and is better able to take in and deliver oxygen to the working
muscles. Muscles develop a higher tolerance to the build-up of lactate, and the
heart muscle is strengthened. These changes result in improved performance
particularly within the cardiovascular system. Interval training also helps
prevent the injuries often associated with repetitive
endurance exercise, and they allow you to increase your training intensity
without overtraining or burn-out. Interval
workouts can gradually help you tolerate oxygen debt. When muscles are overloaded, they cannot
process enough oxygen to burn fuel efficiently, hence the term oxygen
debt. As your interval workouts
increase, you can increase your body’s capacity to handle this oxygen debt.
Imagine
that your muscles are engines that burn fuel (fat and carbohydrate) to keep you
going, and in that engine there are two energy systems, aerobic (more
fat-burning) and anaerobic (more carbohydrate-burning). Individuals
who participate in endurance events that include hills or a sprint at the end,
require that the muscles switch quickly between both systems. For example, say
you're on a long-distance run and you come to a large hill. Along the flat road
your heart rate is at the low end of your training range and you're working
aerobically and burning lots of fat, but then you hit a very large hill. Now
your heart rate increases and you start breathing harder (the work interval of
your interval session), and so your muscles must make the switch to the
anaerobic system where you burn more carbohydrate than fat. If you've put your
time in with interval workouts, then at the top of the hill you'll catch your
breath quickly and be ready to go. But if you haven't been doing intervals,
your recovery will be sluggish (your muscles don't make the switch back to
aerobic metabolism) and your performance will be compromised. In a nutshell,
interval training trains your muscles to switch quickly between the two energy
systems to keep you going, and the results are awesome.
Unless you want
shatter your body into a million pieces, please, warm up before doing these
intervals. The warm ups bring blood and energy into the muscles, the muscles
realize they are being called on and prime themselves for doing work. Our warm
up consists of a mile of light jogging. It
is also an excellent idea to do a few stretches after your warm up. Do not
stretch cold; you will just pull a muscle.
You do not want to pull a major non-warmed muscle during your first
interval burst.
In interval training the cool
down is also important. It starts your recovery off on the right foot. Cool
down with a mile of light jogging winding down your body from the intervals. If
you stop abruptly, the lactic acid in the blood pools and you’ll feel stiff the
next day. No matter how tired you feel,
keep moving. I also recommend stretching
afterward because the leg muscles will be tight after an intense session. Quad,
hamstring, calf, and low-back stretches will help.
How fast is fast?
Intensity is measured on a
scale from 1 to 10. 1 is pretty much standing still, 5 is a light jog and 10’s running as if a lion was chasing you for dinner. Going
from sitting on a sofa for ten years to all of sudden belting it like you made
the 100 meter Olympic final may not be the best thing for your body, hold
yourself back a little; perhaps aim at getting to an 8.5 for your first few
excursions. This will let your body ease into pace of an interval sprint. Be
kind to your body and learn to distinguish what it feels like between pushing
it hard and pushing it over its limit.
These are the main reasons for speed injuries:
Inadequate warmup or cool
down. Be sure to
follow a thorough warmup procedure. By gradually getting the muscles active, you
can avoid the trauma incurred when cold muscles go to maximum exertion. Likewise, it’s crucial to gradually ease off
in a thorough cool down.
Running too hard on easy days. The speedwork and
the long runs will take you to your goal.
You must have easy running days in between these stress days to recover.
Sprinting. Never run at
top speed for there is great risk of injury.
Inadequate transition. Some runners try a “shortcut” up the pyramid
by minimizing or eliminating hill work/speed work the first few sessions. This forces the body to move too quickly from
long slow running to intense speedwork. Jolting the muscles this way tears them down
and makes the rebuilding long and difficult.
Each hill and speed workout is part of a gradual program, a series of
stepping stones in which you gradually apply stress and then recover.
Intervals are
tough but worth the effort. Give it a try and see what you think. Good luck
with your training!