Lower back pain remains one of the most common problems in public health throughout the industrialized world (Strine and Hootman) (Shiri, Solovieva and K.). The prevalence is about 39-54% annually and 60-65% in a lifetime (Hillman, Wright and Rajaranam) (Leboeuf-Yde, N. and Lauritzen). In the United States, lower back pain is the second most common cause of disability, and is the highest cause of disability among men (Center for Disease Control, 2009). An individual quantitative physical examination to detect muscle deficiencies would be very useful for proper placement of workers in demanding physical jobs where back injuries are common. Trunk muscle extensor endurance might be the best approach for this issue.