Beginner's aerobic info.Part1

by Lyle McDonald

Hi again. Well, I realized after posting the list of general
exercise terms that I had failed to explain a few things
adequately, like heart rate reserve and VO2 max. So, in
this post, I will delve further into determining exercise
intensity for aerobic exercise.
VO2 , or oxygen uptake, is merely a measure of the
amount of of oxygen you body is processing at a given time.
It is generally represented in units of ml oxygen / kg body weight / min.
VO2 max is the maximal amount of oxygen your body is capable
of processing at a maximal exercise level. The VO2 max for
an average untrained individual is about 35 ml/kg/min while
some elite athletes have values as high as 70 or more.
This means that the athletes are able to perform at a higher
level than an untrained individual which makes sense.
In any case, unfortunately, measurement of VO2 requires
an exercise lab and rather expensive equipment. However,
one measure of exercise performance, namely percentage
of heart rate reserve, has been found to correlate highly with
a percentage of VO2 max. The old method of determining
exercise intensity was percentage of maximum heart rate but
heart rate reserve has been found to be more accurate as it
takes level of training into account.
Heart rate reserve is found by taking the maximum heart rate
and then subtracting resting heart rate. Max heart rate is generally
estimated by 220 - age. Understand that this is only an estimate
and can vary by up to 10%. For most purposes, however, it is
sufficiently accurate. From this value, subtract the resting heart
rate. The resulting value is the heart rate reserve. Multiply this
value by .6 and .8 to get 60-80% of the reserve and then add
the resting heart rate back in. These two values represent
the Target Heart Range (THR) for aerobic exercise.
So, using myself as an example: I am 23 with a resting heart
rate of 48.
So,
Max heart rate (MHR): 220-age = 220 - 23 = 197.

Heart rate reserve: MHR - resting heart rate = 197 - 48 = 149.

60% = 149 * .6 = 89
80% = 149 * .8 = 119

Adding resting heart rate we get
60% = 89 + 48 = 137
80% = 119 +48= 167.
So my THR is from 137 to 167 to make aerobic improvements.

Let me explain how to take your pulse at rest and at exercise.
The most common places to take pulse are at the brachial artery
at the wrist and the carotid artery in the neck. Using your first
two fingers (not your thumb) press lightly at the selected sight.
Every thump you feel is a heart beat. Count for 10 seconds with the
first count being zero. Multiply the resulting value by six to get
your heart rate in beats per minute. When measuring at the carotid
artery, do not press too hard or you risk causing a pressure response
which could result in fainting.
For resting pulse, I would recommend sitting quietly for a few
minutes before measuring. During exercise, you should probably
take your pulse every few minutes following a five to ten minute
warmup while increasing the intensity (either speed or resistance)
until you reach your target heart rate. While exercising, continue
moving while taking your pulse. Otherwise, you risk fainting due
to the pooling of blood in your legs.
Ok, so now let's examine the components of a good cardiovascular
workout. First and foremost should be a warmup. This should be
five to ten minutes of very low intensity activity to increase heart
rate and raise body temperature. This can be followed by some light
stretching in desired. Then, you should try to spend 20-60 minutes
in the target heart range. This should be followed by a cool down of
5 to 10 minutes of lower intensity exercise. The cool down is important
for a feew reasons. First and foremost is safety. Going from exercise
to a dead stop without a transition period can cause fainting. During
exercise, muscular contraction is one of the primary methods of returning
blood to the heart. If these contractions stop suddenly, there can be
a large drop in blood pressure which may cause fainting. Secondly,
the cool down will help the body dispose of waste products generated
by exercise, especially lactate and may help prevent soreness.
This cooldown can be followed by more stretching in order to
increase flexibility. The stretching prior to exercise was merely part
of the warmup. I will describe proper stretching principles in another
post.
With regard to frequency, the minimum to see aerobic benefits
seems to be twice per week. For body composition changes (i.e. fat
loss), three times seems to be the bare minimum. ACSM recommends
performing 20-60 minutes of work in the target heart range 3-5
times per week.
That wraps it up for now. As always, question/comments to
lyle…@delphi.com.

Lyle

source: misc.fitness newsgroup, 25 Nov 93.

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