This is based on muscle testing comparing those with chronic LBP and healthy, matching controls, where the gluteus maximus, gluteus medius, and TFL are tested. “A significant decrease in gluteus medius strength was observed for the affected side (MMT grade ± SD, 3.35 ± 0.73) compared to the unaffected side (4.56 ± 0.66, p\0.001) or control group (4.46 ± 0.50, p\0.001). TFL strength was significantly greater on the unaffected side (4.93 ± 0.26) compared to controls (4.48 ± 0.50, p\0.001), but not the affected side (4.81 ± 0.44). There were no significant differences in gluteus maximus strength.”
While there is a correlation between glute medius weakness and chronic low back pain, it doesn't necessarily mean that the former is a causation and we can call it a day. Rather, it is likely that pain is the cause of weak hips or any other muscle group.
“To assume the gluteals are dormant is a lot to assume,” said Rick Merriam in an online interview with Massage & Fitness Magazine, who teaches anatomy and kinesiology at the Parker University in Dallas, Texas. “For many years, many people have been told that if they just strengthen their core musculature, they'll avoid back pain or an injury. But yet, every year, billions of dollars are spent on back pain. The missing piece to a complex puzzle that's not being looked at enough is the ability for a professional to figure out which muscles aren't capable of playing their role.
“It's not just one muscle that's dormant. It's many! And the amount or combination of muscles varies, which is why it's important to look at each person as being unique in the way that they're moving as an individual.”
“For example, at the end of the day, many women experience a tight and tired feeling between their shoulder blades. It's something that they don't feel in the beginning of the day. So why are they experiencing that sensation?
“Muscles are fatiguing out. Said another way, there's a tug war going on, gravity is winning, and muscles are losing. When that is the case, the muscles that aren't capable of playing their role or pulling their weight, in which they are under-performing.
“When I say under-performing, I'm saying muscles aren't capable of working in all the ways in which the anatomy books tell us they do. That's where the disconnect starts! For years, professionals have been taught all of these things about how muscles work. And the part that's been left out of the story is, just because they're present doesn't mean they're receiving an optimal amount of feedback from the brain and spinal cord.”
One study rarely justify a support (or refutation) of a claim. Pooling research and data that ask a specific question can give us a better picture of the issue. It's not a perfect system, but it's better than just one plot on a graph.
A 2014 systematic review published in the British Journal of Sports Medicine reviewed 24 papers that examine the relationship between hip strength and knee pain — more specifically, patellofemoral pain syndrome (PFPS). Michael S. Rathleff, Ph.D., from the Department of Health Science and Technology at Aalborg University in Denmark, and his colleagues found “moderate-to-strong evidence from prospective studies indicates no association between isometric hip strength and risk of developing [PFPS].” (3)
While Rathleff and his colleagues found “moderate evidence” from cross-sectional studies that adults with PFPS have lower isometric hip strength than those with no pain, there is some evidence suggesting that adolescents with PFPS don't have hip weakness. Some prospective studies also show that there may be no association between hip strength and risk of developing knee pain.
“Therefore, hip weakness may not be the cause of knee pain — in fact, it is more likely to be a result,” Rathleff stated in an online interview with Guardian Liberty Voice.
“I think adequate strength is important and we should not neglect strength. But the questions is how many with poor hip strength would develop knee pain while lying in their couch watching Netflix?” (4)
Rathleff also mentioned that good hip strength might help people cope better with more knee loading before developing knee pain. For example, it's possible that a runner with general good hip and knee strength might be able to handle more load within longer duration than another runner with lesser hip and knee strength. While this makes intuitive sense, the evidence indicate that poor hip strength is not a high risk factor. (4)
“Because several risk factors for PFPS were described in single studies, these risk factors and other risk factors with conflicting evidence need further investigation in a variety of populations known to have high incidence of PFPS,” the authors concluded.
So the evidence behind weak butts causing knee pain is very weak, but what about hip and low back pain? While there are currently no systematic reviews that examine low back pain or hip pain in relation to having weak hips that is as detailed as literature for knee pain, it is possible to extrapolate the reasoning and principles behind the knee pain literature to other types of pain.
Considering that pain is multi-factorial — biological, psychological, sociocultural — there is rarely one factor that contributes to specific kinds of pain.
“When it comes to pain and injury, it's not about one dormant muscle being the be-all and end-all. Instead, it's a certain combination of muscles that aren't capable of playing their role at a certain time,” Merriam said. “Looking at the bigger picture on how muscles create a pulling force to begin with, you could also say that it's not a about muscles at all. After all, they're just dumb pieces of steak.
“Instead, pain and injury comes down to an insufficient amount of neurological input from the brain and spinal cord. Having asked these questions for 15 years, I can tell you that it's never just about one muscle being dormant or under-performing. It all depends on the individual. It could be any combination of muscles that aren't capable of holding up to their end of the deal. Not because they don't want to, but rather, because they aren't receiving the appropriate amount of feedback from the area that controls everything (i.e., the brain).
Overall, although there is a correlation between pain and hip weakness, the latter isn't necessarily a causation for pain. Strength training, however, is still an essential part of any rehab or physical conditioning program. A plethora of literature indicates that strength conditioning, regardless of the type of exercise, can reduce pain and the risk of getting pain (low back, hip, knee, etc.).
Rathleff still suggests that clinicians should treat the hip or glute musles, but they should not think they have “cured” the cause of their pain just by increasing the patients hip strength.
“This is clinically important because finding the cause of someone’s pain will help you treat the cause and help the patients avoid that the pain returns,” he said. “If we all go around thinking that poor strength is the root of all evil, we will rarely start looking for additional causes of their knee pain.”
1. Press release. Dormant Butt Syndrome May Be To Blame For Knee, Hip and Back Pain. Wexner Medical Center. Ohio State University. May 26, 2016.
2. Copper NA, et al. Prevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controls. Eur Spine J. 2016 Apr;25(4):1258-65. doi: 10.1007/s00586-015-4027-6.
3. Rathleff MS, Rathleff, CR, Crossley KM, Barton CJ. Is hip strength a risk factor for patellofemoral pain? A systematic review and meta-analysis. Br J Sports Med 2014;48:1088–1088. doi:10.1136/bjsports-2013-093305
4. Ng, N. Hip Weakness Not the Cause of Knee Pain. Guardian Liberty Voice. July 4, 2014.
5. Lankhorst NE, Bierma-Zeinstra SM, van Middelkoop M. Risk factors for patellofemoral pain syndrome: a systematic review. J Orthop Sports Phys Ther. 2012 Feb;42(2):81-94. doi: 10.2519/jospt.2012.3803.