M.Tech. / This unblinded, randomised pilot study was performed to determine and compare the effect of innervation specific lumbar spine adjustments and stretching on the flexibility of the rectus femoris muscles in asymptomatic subjects. Twelve asymptomatic subjects between the ages of 20 and 30 years were recruited by the use of advertisements placed around the University of Johannesburg, Doornfontein Campus. The inclusion criteria required that the patient had decreased rectus femoris muscle flexibility (testing positive on the rectus femoris contracture test) and no history of, or any current osteoarthritis or pathology of the hips or knees. The patients were randomly placed into one of three groups by drawing a group number from a closed bag. Group 1 consisted of four subjects receiving a single lumbar spine adjustment per treatment relating to the most restricted segment in the L2-L4 area as well as bilateral proprioceptive neuromuscular facilitation (PNF) of the rectus femoris muscles; Group 2 consisted of four subjects receiving bilateral rectus femoris muscle stretches (PNF); and Group 3 consisted of four subjects who received a single lumbar spine adjustment at the L2-L4 area to the most restricted segment found. One adjustment per treatment was performed. With the subject in the rectus femoris contracture test position, a goniometer was used to measure the knee range of motion bilaterally before and after treatments. These measurements were used as objective data. Each subject was treated twelve times over a four to six week period. The objective results indicated that there was a statistically significant improvement in rectus femoris muscle flexibility in both Group 1 and Group 3. In conclusion, it was shown that specific adjustments at the spinal level of the nerve innervation for the rectus femoris muscle resulted in an improvement of the flexibility of the rectus femoris muscle and with a greater effect on the leg ipsilateral to the side of the spinal adjustment. This gives support for the effectiveness of innervation specific spinal adjustments.