I was originally going to do a little write-up on Vladmir Janda’s prone hip extension (PHE) test, but I found that Dr. Greg Lehman has already done a great job with the topic on his blog. As Dr. Lehman mentioned, we really don’t know what to take from this test from a research perspective. Clinically, many have seen that this test does demonstrate test-retest changes with a successful outcome in a treatment. In fact, I have observed a clinical example in which a patient with hip pain had been participating in numerous closed and open chain exercise interventions that involved hip extension and hip abduction to address their hip pain with no improvement. Yet, ultimately a single prone exercise which emphasized conscious effort to perform isometric gluteal contraction completely resolved her year long struggle with hip pain. Despite this clinical evidence, little research regarding injury and the gluteus maximus has been performed. I thought I’d do a quick blurb on some of the few studies which have shown some correlation between gluteus maximus activation and any injury.
Bullock-Saxton, Janda, and Bullock demonstrated a correlation between ankle sprain injury and an increased delay in gluteal activation2. Similarly, Bruno and Bagust demonstrated an increased delay in gluteal activation in low back pain (LBP)1. One concern with both of these studies were that they utilized the PHE test, in which Dr. Lehman already pointed out previous research showing inconsistencies in activation patterns including the relevance of the gluteus maximus delay. Further yet, since the PHE is performed in “prone”, we have remember, as Gary Gray likes to point out, everything changes once the foot hits the ground. Vogt and his team examined muscle activation patterns in both an LBP and asymptmatic population during walking. In their study, they demonstrated that both the gluteus maximus and the erector spinae were active for a prolonged period of time in an LBP population and that, oddly enough, the glut max fired earlier (although so did the erector spinae and hamstrings) in the gait cycle than the asymptomatic population5. Likewise, during standing extension from a full flexed position, Leinonen et al. demonstrated that in a LBP population, the glut max fired earlier than the erector spinae4. So wait, aren’t we trying to get the glutes to fire earlier as a result of our treatment, or possibly even longer, in the thought of protecting the spine? However, research seems to indicate the body is already trying to do it for us.
So here in lies our enigma regarding gluteus maximus activation and our beliefs regarding its role in musculoskeletal dysfunction. Clinically we’re seeing results with what we perceive to be our gluteal emphasized exercise prescriptions, but it might not be for the reasons we think. As Dr. Lehman mentioned, we may be looking at the wrong variable of gluteal function, perhaps it is peak amplitude or glute max endurance3? Or perhaps our treatments are effecting something else entirely, and simply performing a neuromuscular extensor pattern in the “region of dysfunction” is enough to get a therapeutic benefit (a good future blog topic!). Regardless, we need to be open to alternative explanations for the gluteus maximus enigma, in particular if those explanations come with improved outcomes.
1. Bruno PA, Bagust J. An investigation into motor pattern differences used during prone hip extension between subjects with and without low back pain. Clinical Chiropractic. 2007;10(2):68-80. doi: 10.1016/j.clch.2006.10.002.
2. Bullock-Saxton JE, Janda V, Bullock MI. The influence of ankle sprain injury on muscle activation during hip extension. Int J Sports Med. 1994;15(6):330-334. doi: 10.1055/s-2007-1021069.
3. Kankaanpaa M, Taimela S, Laaksonen D, Hanninen O, Airaksinen O. Back and hip extensor fatigability in chronic low back pain patients and controls. Arch Phys Med Rehabil. 1998;79(4):412-417.
4. Leinonen V, Kankaanpää M, Airaksinen O, Hänninen O. Back and hip extensor activities during trunk flexion/extension: Effects of low back pain and rehabilitation. Arch Phys Med Rehabil. 2000;81(1):32-37. doi: 10.1016/S0003-9993(00)90218-1.
5. Vogt L, Pfeifer K, Banzer W. Neuromuscular control of walking with chronic low-back pain. Man Ther. 2003;8(1):21-28.