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CB
ATHLETIC CONSULTING TRAINING REPORT -
www.cbathletics.com
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ISSUE
#79
INSIDE
THIS ISSUE...
-
"A Lesson in Body Fat Testing"
- "An Even Better Equation for Determining
your Metabolic Rate"
- "Is Weight Training Safe?"
1
- BODY FAT TESTING Q&A
Q:
"I've often had my body fat tested. Sometimes the trainer
has used calipers, and other times used something called
a BIA machine. What method is more accurate? Is there anything
else that I can have done?"
Answer:
You
can trust the caliper method (when performed by an experienced
trainer) and a machine called a DEXA (Dual Energy X-ray
Absorptiometry). The Tanita and BIA (Bioelectrical Impedance
Analysis) scales are less accurate. According to lecture
notes collected from Dr. Mark Tarnopolsky of McMaster University,
even he agrees that visual observation is better than using
a BIA.
You
know something is not right when a "contest-ready" bodybuilder
is measured at 16% body fat by the BIA machine! In fact,
CB ATHLETICS has yet to record a reading of less than 10%
when using the BIA machine, even though a "top-of-the-line"
BIA machine was used. Certainly you would expect a lot more
accuracy from this model! You don't expect 16% body fat
readings when the subjects included competitive bodybuilders
and lean 18-year old junior hockey players.
If
you have a good trainer available, they should be able to
reasonably estimate your % body fat just by looking at your
uncovered midsection. If not, a quick skinfold test (combined
with a good predictive equation) will give you a decent
estimate. One sign of a good trainer is that this won't
cost you a cent.
Q:
"How does a BIA machine determine your body fat?"
Answer:
The
BIA machine sends an electric current through the body.
Fat provides a greater impedance to the current than muscle
(BIA = Bioelectrical Impedence Analysis). The impedance
value is then compared to normative values from a large
data pool, and your body fat is estimated. NOTE: If you
enter a different age, gender, or height, you will get a
different answer!
These
machines estimate body fat percentages using "Regression
equations". The machine takes into account your age, weight,
height, and "impedance value", and puts all of that information
into a mathematically derived equation to help predict your
body fat. A regression equation is based on a large amount
of data. In this case, researchers have determined % body
fat for people of all ages and gender, and then reduced
the data to a predictive equation.
Therefore,
when you change a variable such as your age, the machine
expects a different "body composition" based on "normal"
values. This will result in the regression equation giving
you different values. You will get a difference no matter
what variable you change. For example, if a male enters
his statistics and then inputs female as the gender, the
% fat will increase. Add height to your input and your body
fat will decrease. Inflate your age and % fat will increase.
The
regression equation is also the downfall for testing very
muscular individuals (i.e. athletes). The values are terrible
because athletes don't fit the "normal" data. Once again
though, body fat estimation with the calipers are superior
(when good calipers used by an experienced trainer).
Q:
"Where can I get a DEXA performed?"
Of
the other methods currently available, the most accurate
method is the DEXA. Unfortunately, your chances of getting
one are slim, unless you volunteer for some kind of study
at your local hospital. Outside of research, the waiting
list in Canada for a DEXA is several months long for females
seeking a bone-scan to identify osteoporosis. Many researchers
must schedule DEXA scans outside of 9-to-5 hours in order
to have access to the machine. Of course, this test costs
up to $300!
Q:
"So what method should I use to determine my body fat after
using the GET LEAN program?"
Answer:
Provided
you use the same method for a follow-up test, any method
will be reliable. That is, it will provide an estimate of
how your body changed in response to the fat loss program
you have been following for a given length of time.
2
- THE INFLUENCE OF BODY FAT ON ENERGY EXPENDITURE
After
the last issue, Dr. Digby Sale, Kinesiology Professor at
McMaster University wrote in with this more accurate equation
of energy expenditure. The advantage of this equation is
that it takes fat mass into account and thus more accurately
estimates energy requirements in overweight individuals.
Accounting for fat mass can help an overweight individual
scrupulously design the correct nutritional and exercise
program for fat loss.
To
estimate resting daily energy expenditure (RDEE) the following
equation can be used:
RDEE
= 370 + (21.6 x FFM)
FFM
= Fat-free mass
(Fat
free mass must be expressed in kg)
(For
conversion: 1 kg = 2.2 lbs.)
Example:
For a male weighing 90.9 kg (200 lbs.) with 21% body fat.
FFM
= 90.9 -(90.9 x 21%)
FFM
= 90.9 - 19.2
FFM
= 71.7 kg
RDEE
= 370 + (21.6 x 71.7)
RDEE
= 1919 kcal
Therefore,
a 200 lbs. individual with 21% body fat will have a resting
daily energy expenditure of 1919 kcal.
In
contrast, had the same individual used a more general equation,
the result would have overestimated the caloric needs of
the individual. Using an inaccurate number may impair body
fat loss because calorie intake will remain at weight maintenance
levels. For example, some trainers recommend using Bodyweight
(lbs.) x 11 to estimate RDEE. Using this equation, you will
get:
RDEE
= 200 x 11
RDEE
= 2200 kcal
Even
that is only a difference of just under 300 kcal this overestimation
of calorie needs can severely hamper the fat loss efforts
of many individuals. Furthermore, a recent study suggests
that lean and obese women significantly underestimate their
daily energy intake (Weber et al., 2001). Lean women under-reported
total energy intake (TEI) by 23-30% and obese women under-reported
TEI by ~39%. Inflated calorie requirements and excess calorie
consumption are two strikes against a successful fat loss
program. More accurate food monitoring is a simple step
in the prevention of obesity.
According
to Dr. Sale, the reason FFM is used to calculate RDEE is
that fat is so biologically "inert" that it can be ignored.
That is, fat does not burn energy at rest, while muscle
does. Muscle contributes a significant portion (20-25%)
of the RDEE. If the male in the above example increased
his FFM to 76 kg with a weight training program, his RDEE
would increase to 2012 kcal, a 5% increase in metabolism!
Score another one for weight training as a method to help
lose body fat. In contrast, changes in body fat have virtually
no effect on RDEE.
Dr.
Sale also provides an example of the metabolic power of
muscle using the estimate that muscle represents 50% of
total body mass. This is a reasonable estimate for healthy
young males with "normal" body composition (~10-15% body
fat). For females and obese individuals, the percentage
of total body mass that is muscle would be lower because
of their higher % body fat.
In
our example, muscle mass would be ~45 kg in a 90 kg male.
Muscle
mass = 90.9 x 0.5
=
45.45 kg
In
ISSUE #78, it was estimated that muscle
contributes 25% to total RDEE. Therefore, muscle mass would
contribute 480 kcal to the man's daily energy expenditure.
RDEE
= 1919 x 0.25
=
480 kcal
This
works out to 9.6 kcal/kg muscle/day (4.4 kcal/lb). This
is a far cry (one-tenth!) from the estimate that each pound
of muscle burns 50 kcal. Chalk that up as another health
and fitness myth.
The
"resting" metabolic rate of muscle can be transiently elevated
after exercise. This is particularly true after high intensity
exercise, including resistance exercise. Carrying extra
fat increases energy expenditure during load-bearing activities,
but this occurs due to increased requirement of muscle work,
not due to an increase in fat tissue energy expenditure.
Dr. Sale concludes, "the best way to increase resting energy
expenditure is to increase muscle mass and perform regular
intense exercise".
References:
The
RDEE calculation was taken from McArdle, Katch, and Katch's
exercise physiology textbook (4th edition, 1996, page 154)
where they cited:
Cunningham,
J.J. Body composition and resting metabolic rate: the myth
of feminine
metabolism.
Am. J. Clin. Nutr. 36: 721, 1982.
Weber,
J., et al. Validity of self-reported energy intake in lean
and obese young women,
using
two nutrient databases, compared with total energy expenditure
assessed by
doubly
labeled water. Eur. J. Clin. Nutr. 55: 940-950, 2001.
3
- TRAINING SAFETY
Q:
"Sometimes when I do heavy leg presses I end up having to
cut my workout short due to headaches. Other times, I develop
a headache after training that persists for hours. What's
going on?"
Answer:
Exertion
headaches are very common during exercises such as the leg
press. In fact, in CB ATHLETIC research conducted at McMaster,
a male subject dropped out of the study because his doctor
diagnosed him with exertion headaches (due to the intense
leg press exercise protocol). It's not surprising though,
considering McMaster professors Dr. Digby Sale and Dr. Duncan
MacDougall had previously shown increases in systolic blood
pressure of up to 350-400 mmHg during heavy leg press exercise
(NOTE: resting systolic blood pressure is only 120mmHg!).
For
people that suffer from exertion headaches, they should
first consult their doctor to determine if there are any
additional concerns. Barring other problems, the lifter
should reduce the intensity and volume of the exercises
that lead to headaches, or remove them completely from training.
There is little reason to push to the onset of headaches.
Simply find a substitute exercise for the leg press.
Furthermore,
after pushing yourself that hard on the leg press, take
your time returning to the standing position. Your blood
pressure will rapidly decrease to normal and the movement
of blood away from the head (as you stand) could lead to
dizziness and fainting. This is definitely not something
you want to occur in the weight room when you are surrounded
by iron and other lifters.
Q:
Wow. Based on that response, is weight training considered
dangerous?
Answer:
While
controversial, the answer to that question is, "no". Relatively,
weight training is not dangerous, as the injury rate is
much lower than that in other common sports such as hockey,
football, or even soccer. However, it is possible to be
injured while lifting weights, but one must understand that
these injuries are most often due to improper technique
or poor equipment.
For
example, a close friend recently dislocated his shoulder
while training. It was a serious injury and it set him back
nearly a year of progress, which was very frustrating because
he was making great gains up to that time. Most importantly,
it didn't have to happen. After all, he trains with proper
technique (not perfect, but well enough that no injury should
occur) and he was using a familiar exercise. Unfortunately,
he just didn't take into account the limitations of the
equipment.
Here's
how it happened: He completed a set of incline bench presses
and was attempting to rack the weight when he overestimated
the distance to the rack. His arm extending back under a
heavy load, thus dislocating his shoulder. First off, this
is evidence that supports the recommendation that everyone
should always train with a spotter. Second, this situation
suggests that you should become very familiar with the set-up
you are about to use.
Ask
yourself a few questions before you begin your next workout.
Is your equipment going to be your downfall, despite your
perfect technique? Is there any safety mechanism that will
prevent the weight from falling on top of you in the case
of a missed lift? Is the equipment stable and well taken
care of? Get familiar with your gym and always use a spotter
for heavy or fatiguing lifts!
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