Post Lab 10
The Composition of the Body
The main purpose of this lab is to learn a detailed, in depth description of the
hydrostatic technique for determining body composition. This is so that any individual may
utilize this information to construct a system to quantify human body-fat tissue. The second
purpose of this lab is to also learn the theoretical implications and assumptions used when using
the hydrostatic technique in determining body composition.
Before measuring and weighing is commenced, the individual should not eat, drink,
smoke, or engage in strenuous activity.
The individual should come in prepared wearing his/her bathing suit and bringing his/
her own towel
The following equipment will be needed for the lab:
Scale, Tare, Thermometer, Hydrostatic tank, computer, towel, CBC software, and
Record, height, weight, and age on the provided data sheet. When recording the
weigh, the individual should be in the attire to be worn during the weighing.
Record the tare weight and the temperature of the water
Remove all jewelry prior to entering the tank.
The subject enters the hydrostatic tank. He/she should be completely immersed in the
water with all the air bubbles removed from skin and hair.
Complete underwater weighing according to the instructions provided by the teaching
assistants, by discussion in pre-lab lecture, and by demonstration.
The subject’s lungs must be as nearly deflated as possible, maximal
expiration, with a correction made for the air remaining in the lungs called
After completing 5 successful weight readings, the subject may leave the tank.
Subtract the tare weight from the underwater weight to receive the real underwater
weight of the subject.
Enter data into CBC program to calculate the % fat
% fat can be found using the Rathbun and Pace, Siri, or Brozek at al % fat
equations. But the Siri is used the most because it yields a midway value for