THE EFFECT OF FATIGUE ON MULTIJOINT KINEMATICS, COORDINATION, AND POSTURAL STABILITY DURING A REPETITIVE LIFTING TEST

Because of the inability of strength tests to accurately discriminate between low back pain patients and healthy subjects, a multifactorial evaluation of low back pain patients is warranted. It is postulated th at measurements of endurance, kinematics, postural stability and coord ination, in addition to strength, are necessary to fully document the patients' functional capabilities. This research study was conducted i n order to understand the effects of fatigue on the above factors. Twe lve healthy male subjects performed a repetitive lifting test in which a submaximal load was lifted at a maximal rate. Knee, hip, and trunk motion was measured using videography and electrogoniometry, postural stability was measured using a forceplate, and coordination parameters were determined using phase-plane analysis. Fatigue was documented by a 31% reduction in lifting power. At the end of the endurance lest, t here was less knee and hip range of motion and greater spine peak flex ion, while the coordination measures demonstrated that there was great er hip and lumbar spine extension earlier in the lifting phase. The po stural stability declined as the test endured. Utilization of these me asures may guide physical therapists in their rehabilitation of low ba ck pain patients.