This test method covers the measurement of certain angular motions of the lower extremity during running, specifically, the frontal plane projection of the pronation and supination of the lower leg relative to the foot ("rearfoot motion") and methods by which the effects of different running shoes on rearfoot motion may be compared. As used in this test method, footwear may refer to running shoes, corrective shoe inserts (orthoses) or specific combinations of both. The effects of orthoses may vary from shoe to shoe. Therefore, comparisons involving orthoses shall be qualified by the specific style of shoes in which they are tested. This test method is limited to the measurement of the two dimensional, frontal plane projection of the relative angular motion between the lower leg and the foot ("rearfoot motion"). It is not a direct measure of pronation or supination, which are three dimensional motions. This test method is limited to running motions in which the heel makes first contact with the ground during each step. This test method is applicable to measurements of rearfoot motion made while subjects run on a treadmill or while they run overground under controlled conditions. The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.