The total number of normal/able-bodied participants will be collected from 4 independent research centers in the U.S. and Canada with an expected maximum of approximately 60 individuals per center. A sub-group of 32 randomly assigned able-bodied volunteers will be scheduled for a second MPR test approximately 7 days after their initial testing to examine the reliability of the MPR evaluation tool. In the selection process, every effort will be made to avoid bias toward a non-working population (i.e. testing only in the morning or afternoon) and to obtain representative proportions of the age and race classes existing in North America.