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Many authors have speculated that low back pain may occur as a result of excessive stress on the lumbar spine and sacroiliac joints due to an exaggerated anterior pelvic tilt posture (3,5,9,10,14,17). The degree of pelvic tilt and lumbar lordosis are frequently assessed as part of a postural evaluation. Treatments based on decreasing the amount of anterior pelvic tilt and concurrently reducing the depth of lumbar lordosis, or increasing the amount of anterior pelvic tilt and concurrently increasing the depth of lumbar lordosis, are often prescribed in an attempt to correct postural deviations and to treat pain and dysfunction related to postural syndromes (33-10). Despite the often-stated relationship between pelvic tilt and lumbar lordosis, little has been published to demonstrate how voluntarily altering pelvic tilt affects lumbar lordosis. The purpose of this study was to investigate the effects of altering the angle of pelvic tilt on lumbar lordosis in the standing position.Pelvic tilt (Figure 1) is defined as the angle between the horizontal plane and a line passing through the midpoint of the posterior superior iliac spines and the midpoint of the anterior superior iliac spines (12). Lumbar lordosis (Figure 2) is the curve assumed by the lumbar spine, where the lumbar spine forms an anterior convexity (2). The degree of lumbar lordosis is variable among individuals and is the result of many

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The damaging effect of transient loads on joints has been observed in vitro and in vivo, and may be an aetiological factor in osteoarthrosis. The events around heel strike, when the velocity of the foot is brought rapidly to zero, may be a source of such loads in normal activity. By modifying the rate at which the limb descends to the ground, quadriceps action influences the magnitude of the heel strike transient. Experiments were carried out to analyse the occurrence of these transients, and a two-dimensional mathematical model of the knee joint and lower leg was used to calculate the forces developed at the knee in response to them. Paralysis of the quadriceps resulted in a large increase in the heel strike transient.

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