Subcutaneous body fat can be measured using a device called a skinfold caliper. In an average person, approximately 50% of body fat is distributed just below the skin. For this reason, body composition can be easily measured using the right tools and formulas. Skinfold Formulas are derived from calculations based on extensive research derived from Hydrostatic weighing. In general, the skinfold caliper method produces a measurement that is _+2.0 to3.5% of that obtained in Hydrostatic weighing. Further, measurement error as range as high as to 6 to 8 % if the trainer is inexperienced or using poor technique, if the man or women are obese or extremely thin, or if the caliper is not properly calibrated. Before conducting skinfold measurements, you must familiarize yourself with the exact site locations and proper grasping technique.
Given the variability in fat distribution from site to site, it is recommended that multiple sites be analyzed. Most research supports using at least three sites when assessing body fat. The sites are also different men and women. For men, the Jackson and pollock three-site skinfold locations are as follows(jakson&pollock, 1985):
Chest: A diagonal skinfold taken midway between the anterior axillary line(crease of the underarm) and the nipple
Thigh: A vertical skinfold taken on the anterior midline of the thigh between the inguinal crease at the hip and the proximal border of the patella
Abdominal: A vertical skinfold was taken 2 cm(~1 inch) to the right of the umbilicus
For Women, the Jackson and Pollock three-site locations are as follows (Jackson & Pollock, 1985):
Triceps: A vertical fold on the posterior middle of the upper arm taken halfway between the acromion (shoulder) and olecranon (elbow) processes.
Thigh: A vertical skinfold taken on the anterior midline of the thigh between the inguinal crease at the hip and the proximal border of the patella.
Suprailium: A diagonal fold following the natural line of the iliac crest taken immediately superior of the crest of the ilium and in line with the anterior axillary line
Skinfold caliper, property calibrated (e.g.‚ Slim Guide, Lange, or Harpenden)
Marking pencil (optional) Pre-test procedures:
To ensure testing accuracy, the client should be optimally hydrated and always be measured prior to exercise. Since this particular test can feel intrusive to a first-time client, then you should make sure the client is familiar and comfortable with the protocol. If a marking pencil is to be used, it should be washable; an eyeliner pencil works well.
To ensure accuracy in assessing body composition using the skinfold caliper method, it is important to measure each skinfold in the appropriate location and use standardized techniques:
All measurements are taken on the right side of the body while the client is standing
Skinfold locations should be properly identified using anatomical Landmarks and measurements. The use of a marking pencil will help ensure precise Landmarks and consistency.
Hold the calipers in the right hand, grasping the skinfold site with the left hand. (Left-handed calipers are available, which reverses the hand position.)
The thumb and index finger of the left hand are opened to about 8 cm («3 inches) and positioned 1 cm («Va inch) above the measurement site. Grasp or pinch the skinfold site, making a told line (double told of skin) that corresponds to the site instructions.
To accurately assess subcutaneous fat, the skin and underlying fat are simultaneously pulled firmly away from the underlying muscle tissue.
The pinch is maintained while the calipers are positioned perpendicular to the site and on the site location (1 cm below the thumb and index finger), midway between the top and the base of the fold.
Slowly release the caliper trigger, reading the dia! to the nearest 0.5 mm approximately two or three seconds after release.
After taking the skinfold reading, gently squeeze the trigger to remove the caliper before releasing the skinfold pinch.
Moving on to the next site, repeat the above steps. Each site should be measured a minimum of two times to ensure consistency between measurements. If subsequent readings produce a difference greater than 2 mm, a third measurement is necessary and the average of the two acceptable scores should be taken (i.e., within 2 mm of each other). It is recommended that the trainer wait 20 to 30 seconds between measurements to allow the skin and fat to redistribute.
Use Siri (1961) Equation to calculate Marci’s percent body fat
Determine body composition is essential for a personal trainer who is designing a personalized exercise program, especially if the primary goal is either weight loss or weight gain. Reducing excess adipose tissue is also important for any person trying to decrease his or her risk of major disease and dysfunction. To enhance the program’s effectiveness, appropriate exercise should be used in conjunction with evidence-based dietary recommendations. Body-composition values can also be used to determine a goal weight. This calculation is based on the assumption that throughout the fitness program, lean body weight or mass will not change. However, it should be noted that with any weight loss or gain, there is typically a change in the amount of both lean body mass and fat mass.
Consider a 47-year old man who weighs 212 pounds (96kg) and has an estimated body-fat percentage of 21.3%. His goal is to reach a body-fat percentage of 14 to 17%, which is the range for men desiring optimal fitness. To calculate this man’s weight for the desired range, his lean mass must first be calculated. Since 21.3% of his body weight is fat mass, 78.7% of his weight is lean mass (100%-21.3%=78.7%). The decimal form of the percentage figures is used to derive a lean mass of 167 pounds (76kg).
Step 1: 100%-Bodyfat percentage=lean mass percentage
Step2: Bodyweight × Lean mass percentage=Lean mass
212 pound × 0.787=167 pound (76kg).
Step3: 100-desired body-fat percentage= Desired lean mass percent
upper limit: 100-17%=83%
lower limit: 100-14%=86%
Step4: Lean body mass/desired lean body mass percentage=desired body weight
167/0.83=201 pound (91kg)
167/0.86=194 pound (88kg)
The weight range corresponding to a desired body-fat percentage of 14 to 17% is 194 to 201 pounds (88 to 91 kg). With regular aerobic activity, resistance training, and dietary management, this man would need to lose a minimum of 11 pounds (5kg) of fat weight (212-201=11 pounds;96-91=5kg)