The subject should be standing upright with weight evenly distributed on both feet, the right arm bent 90 degrees at the elbow, and the right palm facing up.
1. Mark the spot.
Measure the upper arm length, from the uppermost edge of the shoulder blade down to the tip of the elbow bone. Mark the midpoint.
2. Pinch the skin. Using your thumb and index finger, grasp a fold approximately 2 cm above the mark. Make sure that the skinfold goes down along the arm.
3. Position the caliper: Ensure that the mark remains centered between the caliper tips and that the jaws sit perpendicular to the length of the skinfold.
General rules: taking skinfold measurements.