Prone Hip Extension Test (PHE): The test is made to assess the pattern of muscle firing and thus muscle imbalances (Bruno, 2011).
The test is performed with the patient lying prone on the treatment table, the arms are at the side and the head is in neutral position, if possible. The examiner puts one hand above the ipsilateral gluteus maximus and the other hand on the lumbar spine region, in such a way that the hand is touching both erector spinae at the same time. The patient is asked to extend the leg up and the examiner has to notice the pattern of recruitment of the muscles. Hamstrings are the first followed by the gluteus maximus, the contralateral erector spinae and finally the ipsilateral erector spinae.
The imbalanced pattern correspond to the delayed activation of the gluteus maximus, so using more the spinal muscles. The worst faulty movement is when the thoracolumbar extensors are starting the movement or even the shoulder muscles. This pattern is easily recordable when anterior pelvic tilt and hyperlordosis are present and it is sign of hypertrophic spinal extensors and weak counteracting abdominals. Another pattern that can be found is the flexion of the knee while the hip lifted. This is sign of hamstring prevalence or hypertrophy over the gluteus maximus (Page et al. 1967). To conclude this test is useful because as Page et al (1967) states “it is generally agreed that a delayed recruitment or a weak activation of the gluteus maximus induces compensatory overload stresses on the lumbar spine that are accompanied by simultaneous thoracolumbar erector spinae overactivity”.
Bruno et al (2011) conducted a research on the validity of the PHE test with the following findings: Sensitivity 63.6%, Specificity 81.3%, Positive predictive value 53.8%, Negative predictive value 86.7%, Likelihood ratio of a positive test 3.394, Likelihood ratio of a negative test 0.448.