Duel emission x-ray absorptiometry is the absolute gold
standard for body composition assessment of living tissue. (The only way to
directly measure body composition is post-mortem ether analysis which involves tissue
liquefaction. So far, no clients have been interested in this one-time evaluation.)
With DXA scanning two types of energy
are passed through the body, each one absorbed by different tissue densities.
The two images are then subtracted from each other, and it is possible to
ascertain fat mass, lean body mass, and bone mass/density.
I have done two scans in 2012 at Dexa Fit Chicago, and I must say, aside from
some of the news being unwelcome, it is a revelation. My first scan, which established
a baseline, was in January. Right off the bat, I had to adjust my understanding
of the results. DXA scanning will provide a much higher body fat percentage
than other methods as it is able to measure all fat in the body. The majority
of methods, including the standard benchmark method of skinfold
calipers, tend to focus on subcutaneous fat, the fat that lies between the
muscle and the skin. DXA
scanning can also measure the intramuscular fat (think of marbling in a slice
of beef) and the visceral fat which lies deep within the intestinal cavity.
Was I happy about my results? Not at all. The truth can be, well,
inconvenient. I took it on the chin, turned my cheek, and set my goals. Six
months later this past July, I had a follow up scan. I had expectations, and
they were realistic based on where I knew I was. (I knew I wouldn’t quite be where
I hoped to be when I originally set my goals.) Wait, what? A trainer that didn’t
meet his goals? How is this possible? Well before I explain, let me tell you
what the DXA scan revealed.
Results : Body fat
As hoped, my bodyfat percentage had dropped, and as
expected, it was less of a drop than I wanted or should have been able to pull
off. So; should have been, could have been better. Certainly will be better in
the next scan three months from now, new goal set!
Results : Muscle mass
Any lowered bodyfat percentage, even modest, is always good,
but this one was tempered with a drop in lean body mass as well. That is, of
course, NOT good. So what happened? Rather than panic, I looked at the wealth
of data my scan provided.
DXA scans divide the body into regions, allowing you
determine where the changes are taking place. The high level of precision is
carried over to each arm, each leg, left and right sides, torso, etc. This is
incredibly important, and as a trainer, this is the data that most interests
me. So that did happen to my body over the last six months? Well, most of the
fat I lost was android fat, the fat around the midsection, and in the
midsection my fat lost was significantly higher than my overall average. Great
news! Where did I lose my lean muscle mass? Upper body, arms, and trunk were
all stable, I lost the muscle mass in the legs. This is not a good thing, not
at all, but information is power, and the clarity the DXA scanning brings to my
analysis is why I am so pleased with the results.
Analysis
Here is how it happened. This summer has been a new life for
me. I am cycling around the city to client sessions and classes; on average 20
miles a day, and rowing at the boat club; up to two hours a day. I have been
spending up to 6 hours a day outdoors, often in brutal heat, and up to 5 hours each
week working out. This has increased my demand for nutrient and hydration to
levels I have never had to maintain. I realized only recently that I had to
watch electrolytes with a precision unlike anytime in my past. I had been
propping up my flagging energy with carbohydrates, probably more than
necessary.
Fat mass
Maintaining a low carb diet to get ripped under above
circumstances would in incredibly taxing, but now that I know most of my energy
loss was due to electrolyte mismanagement I can reduce the carbs to favor fat
loss while sparing muscle mass.
Muscle mass
Both cycling and rowing favor muscular endurance (so called
density) over hypertrophy (size). Both develop slow twitch muscle fibers over
fast twitch. This means that this shift in training resulted in a reduction in muscle
mass through the legs. This is why I am so pleased with the results of the DXA
scan. I am now fully aware of what has happened, don’t need to panic, and have
the knowledge of what to alter in my current regimen. I also need to remember
that it will be an uphill battle during the water season to pull this off, but
I will increase my weight lifting to keep hypertrophy in the mix. I will also remember
to take the long view and focus on leg mass come winter when it will
be a piece of cake. Absolute proof of the principle of periodization.
This was a long post, and I thank you for your patience if
you made it to the end. If you are one of my clients, I highly recommend you
consider a DXA scan. I will be happy to schedule one for you at Dexa Fit Chicago
with Matt Ulrich.
Check out their link to learn more: http://dexafit.com/350
You can see how I am
able to leverage DXA scans to improve my own training; imagine how I can leverage
your results in designing a program for you.
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