Hi, I am currently writing my dissertation on the effects
of Sports Supplements on Body Fat % and the comparison of tools
as a measure. I have thoroughly enjoyed using your website as
a source and was interested how your body fat % calculator works.
The skinfold calculator
identifies both 3 and 7 site calculators BUT I have found many
websites and equations require waist and forearm circumferences.
Could you please explain how that is not required by your calculator.
If possible any reading on this matter would be greatly appreciated.
I look forward to your response. Once again a great resource!
These formulas have
been around for many decades. The references are provided near
the bottom of the mentioned calculator. You can look those studies
up on PubMed. They will give you a comprehensive understanding
of the science involved in these formulas.
When I was in college (KSU), many soldiers from Fort Riley,
who where considered overweight when measured by circumference
measurements, would set appointments with our lab and pay money
to have their body composition (with lung volume) tested because
it was much more accurate than measuring girths as they do in
the Army. But obviously that requires a specialized laboratory,
equipment, and a higher level of expertise to administer such
In a clinical setting, skinfold measurements offer a more
practical alternative in estimating body composition and is more
accurate then the alternatives like bioelectrical impedance,
near inferred, ultra-sonic, MRI, and circumference measurements,
etc. In my experimental methods class, I also conducted a study comparing
skinfold measurements with a formula using waist circumference
in college men who weight trained. In this study, we found that
if men had an enlarged musculature of the midsection (i.e. developed
ErectorSpinae, Obliques Rectus Abdominis), that circumference
measurements would under estimate lean body weight therefore
increasing the estimated percent body fat.
In a clinical seating, you will need to look at the changes
of body composition occurring over time since there is a degree
of measurement error with skinfold and even circumference measurements.
For this reason these indirect measurements have not been considered
accurate enough for academic research examining body composition
changes over time. Wilmore, et. al. (1970).
You can also do more research in this area on PubMed. I can
also recommend certain textbooks from the Fitness
Testing section of the ExRx.net store.
Wilmore JH, Girandola RN, Moody DL (1970). Validity of
skinfold and girth assessment for predicting alterations in body
composition, Journal of Applied Physiology, 29 (3), 313-317.
If I understand the instructions right the second line
is the length of the lower leg thus when the back knee touches
the ground the knee be touching the front heel. The picture has
about a 6 inch gap. What am I missing?
Notice the rear ankle is dorsiflexed AND the toes are hyperextended
accounting for most of the the distance you see from top of knee
to back of the heel of opposite foot. In addition, the tip of
the toes are behind the line, not the bottom of the foot. Do
the measurements yourself seated with the low leg positioned
horizontal. You'll discover a similar difference when you perform
Lunge as instructed.