NASM essentials of sports performance training
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NASM essentials of sports performance training

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it pumps blood to the body. Normal sys-
tolic pressure ranges from 120 millimeters of mercury (mm Hg) to 130 mm Hg. The diastolic
blood pressure (lower number) signifies the minimum pressure within the arteries through a full
cardiac cycle. Normal diastolic pressure ranges from 80 mm Hg to 85 mm Hg. 
Blood pressure is measured using a sphygmomanometer, which consists of an inflatable cuff, a
pressure meter with an inflation bulb/valve and a stethoscope (this can also be done using a
digital device). To record blood pressure, instruct the athlete to assume a comfortable seated
position and place the appropriate size cuff on the athlete, just above the elbow (Fig. 3.6).
Next, rest the arm on a supported chair (or support the arm using your own arm. If done while
FIGURE 3.5 Carotid pulse.
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standing, secure the arm between your own arm and chest) and place the stethoscope over the
brachial artery (in the coronoid fossa of the humerus) using a minimal amount of pressure.
Rapidly inflate the cuff to 20 to 30 mm Hg above the point when the pulse can no longer be
felt at the wrist; most people inflate the cuff to around 200 mm Hg, but this can vary between
athletes. Next, open the valve on the bulb to release the pressure at a rate of about 2 mm Hg
per second, listening for the pulse while watching the pressure meter\u2019s reading decline. To de-
termine the systolic pressure, note the pressure when you first hear the pulse through the
stethoscope. Diastolic pressure is determined when the sound of the pulse fades away. For
greater reliability, repeat the procedure on the opposite arm. This procedure needs to be prac-
ticed to become proficient. In addition, there are standards regarding cuff size based on the
subject\u2019s arm circumference. Athletes with larger arms need to be tested with a wider cuff and
athletes with smaller arms need to be tested with a narrower cuff. Using the wrong size cuff will
give inaccurate results. A true measure of a person\u2019s blood pressure is done by a health-care
professional. If a person\u2019s blood pressure seems high, suggest that they see their personal
health-care provider where a clinically relevant blood pressure will be determined. 
FIGURE 3.6 Proper sphygmo-
manometer placement.
Blood Pressure Cuff Sizes
If arm circumference is Choose from the following cuff sizes
Up to 13.4\u201d 27\u201334 cm Adult cuff
13.7\u201317.3\u201d 35\u201344 cm Adult large cuff
17.7\u201320.4\u201d 45\u201352 cm Adult thigh cuff
Gathering body composition statistics about an athlete provides a measure of an athlete\u2019s start-
ing point. Repeated measurements of body mass, skin-fold thicknesses, circumferences, and
body mass index can be very motivating pieces of information for an athlete. Changes in the
athlete\u2019s body composition (decreasing body fat, increasing lean body mass) may also be re-
quired for their sport. In addition, it is a good indication of how well the training program has
been designed.
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An important piece of information is the athlete\u2019s starting body fat percentage. Lean body mass
is important for all athletic activities, so knowing one\u2019s body fat percentage can help determine
an estimate of the athlete\u2019s lean body mass.
Body fat can be measured in a variety of ways. The choice of method depends on the avail-
able tools and expertise. Below are common ways to assess body fat percentages:
1. Skin-fold calipers are used to measure the thickness of an athlete\u2019s subcutaneous fat
(the fat beneath the skin) at specific anatomical sites. When properly performed, the
thickness of a double layer of skin and the underlying fat is measured. The procedure
looks simple, but requires a lot of practice to be skilled and accurate. Taking a meas-
urement by as little as an inch from the appropriate site can mean a 25% error of
2. Bioelectrical impedance uses a portable instrument to conduct a minute electrical current
through the body in order to measure fat. This method is based on the hypothesis that
tissues high in water content conduct electrical currents with less resistance than those
with little water (such as adipose tissue). As such, this method is highly sensitive to wa-
ter content of the tissues and body. Take readings before and after a workout to see how
much the results can change. The devices come with very strict procedures to ensure a
valid measurement is obtained. 
3. Underwater weighing is a method of determining the proportion of fat to lean tissue
based on the method of Archimedes. The procedure compares the difference between
dry, land weight with underwater weight, correcting for air in the lungs and water density.
Because lean tissue is denser than fat, the leaner person will weigh more under water
(they sink). Those with more fat sink less. The results of underwater weighing determine
a person\u2019s overall density (compared to the water) and as such, are a composite of body
weight to body volume. As few people understand what it means when they are told they
are 1.083 g/cc, the density figure is converted to a percent body fat figure that is easier to
interpret, understand, and explain. The process requires practice by both the technician
and the athlete, as many people are uncomfortable going under water and being told to
completely exhale, and then remain still for a few more seconds while the scale is read.
Of course there are more elaborate tanks with digital scales and closed rebreathing sys-
tems that are more comfortable, but these are found mostly in research labs. For many,
underwater weighing continues to be the gold standard of body composition measure-
4. Whole body plethysmography involves air displacement in a closed chamber. The most
visible product, the Bod Pod, works along the same principle as underwater weighing and
can be found in research labs and many larger commercial clubs. In this process, air dis-
placement is measured instead of water displacement as in underwater weighing. The pro-
cedure is quite comfortable, but those with some claustrophobia might have problems.
The Bod Pod is expensive and may not be conducive to all environments.
5. DEXA scans use a small dose of radiation for measuring body compartments. A primary use
is in determining bone density, but is also used to determine body composition. This is
only found in research settings and is too expensive to be in common use commercially.
Most Sports Performance Professionals do not have an exercise physiology laboratory at their dis-
posal, so the skin-fold caliper method will usually be the method of choice when assessing body
compensation. To be accurate, you must be familiar with finding very specific anatomical land-
marks, be obsessive (and somewhat ruthless) about pinching the skin fold, be consistent in the
pressure used when pinching the skin fold, be careful regarding the placement of the caliper
(Should the skin fold be vertical, horizontal, diagonal? Should the calipers be placed above or
below your fingers? It matters!), be aware of how far the caliper is placed from the fingers pinch-
ing the skin, and the length of time the calipers are left on the skin all the while remembering to
read the meter and then open the caliper when removing (if not, you abrade the skin and get a
less than favorable response from the athlete!). Other factors also need to be consistent. For ex-
ample, the calipers should be placed on the skin rather than through the clothes. The reading
should be taken at the same time of day, preferably before a workout, and the caliber should be
carefully chosen because not all calipers are equal. Consistency and obsession with technique are