Field measurments during skiing experiments simultaneously recorded the complete excitation of the toe and heel of one foot, the absolute spatial orientation of the pelvis and the foot, muscle activity at the hip, knee, and ankle, and the complete rotation of the femur in relation to the tibia across the knee in three test subjects. Analyses of field data show that the magnitude of the loading applied to the lower extremity during normal skiing often exceeds the expected, quasi-static, ultimate strength of the tibia. Anterior-posterior bending of 580 N multiplied by (times) m has been recorded during skiing, without binding release (release setting less than 300 N multiplied by (times) m) or injury to the test subject. The standard heel binding design which controls the heel hold-down force cannot effectively control the bending moment in the lower extremity during skiing. The verticle force at the toe was found to provide a good measure of bending in the tibia. Longitudinal rotation across the knee was in phase with, though not proportional to, the applied torsion at the foot by the ski. These results indicate the increased complexity of the injury and protection problems.