Just to further muddy the water in this debate, I had a serious ankle injury to my right ankle (same side as the knee problem), which stopped me from training for 6 months. The ankle doesn't hurt atm, but the foot is now tilted to the outside when standing flat footed, so that more of the weight is carried on the outside of the foot relative to the non-fucked ankle. Not sure there is any way to fix this, but ankle exercises are part of my standard warmup now. I also had hip-flexor problems on that side last fall.
Regarding the VM/VL debate, I noticed that when releasing the VL on either a foam roller or using a tennis ball results in immediate relief from my knee pain, leading me to give favour to a VM/VL balance issue as being a cuplrit in the pain itself.
I'm quite sure there could be several issues for PFS, as its a pretty broad term for knee pain.
Here is one of the studies that I referenced, in regards to VL and VM/VMO imbalance... I found the hard copy in my stack of journals that are collecting dust in my closet. Although I haven't searched for it online, this is where you can find it in print.
From the Journal of Strength and Conditioning Research, vol 24, no 5, may 2010
"The Effect of Closed-Kinetic Chain Exercises and Open-Kinetic Chain Exercise on the Muscle Activity of Vastus Medialis Oblique and Vastus Lateralis", by Sian E. Irish, Adam J. Millward, James Wride, Bernhard M Haas, and Gary L.K. Shum
Found it! So they found that %MVC in a couple exercises (especially double-leg squats with isometric adduction) is relatively high in VMO when compared to VL. My biggest question would be whether this actually produces a therapeutic effect (specifically, reducing pain, since we're talking PFS), especially since these subjects were asymptomatic. It's an easy assumption to make, but I'd like to actually see that connection made. They also used an unadjusted (I assume) least-significant difference test to determine significance, which is highly suspect, particularly when their significance level is only 0.05. Exercise order and the possibility of carryover weren't controlled for either, as far as I can tell. Maybe I just missed something on that last piece.
Originally Posted by blackmonk
So, basically, while it looks like this might be a decent baseline to show that selective firing of VMO is possible (though the LSD and testing order still definitely bother me), I'd like to see a connection to actual therapeutic effect before advocating this to a symptomatic individual.
Thanks for the citation, man! Would love to see more stuff along this line. And again, if you've got any anecdotal reports, I'd be interested to hear that as well.
Re: Knee and support structure mechanics
Anecdotally, I have seen knee injuries rehab very quickly with adduction and posterior chain exercises.
I'll keep looking through my other journals.
Originally Posted by ChenPengFi
I've seriously never heard this theory before, whereas I've seen hamstrings come up everywhere in the context of knee stability. A few examples:
-My old S&C coach tried to convince our running backs to bend their knees more when they cut so the hamstring would take over for the ACL (something along these lines)
-I opened up Starting Strength, and the first thing Amazon shows me is a diagram of the hamstring preventing anterior translation of the top of the tibia/fibula when squatting (Figure 2.9, if anyone's curious)
-Studies like "Effect of Gender and Maturity on Quadriceps-to-Hamstring Strength Ratio and Anterior Cruciate Ligament Laxity" and "The relationship of hamstrings and quadriceps strength to anterior cruciate ligament injury in female athletes" are pointing at relative hamstring weakness as a contributor to the high rate of non-contact ACL injuries in female athletes
-I've personally actually had my knees feel uncomfortably lax when doing wall ball shots after fatiguing my hamstrings.
Glutes, though... I just don't see it from a physics perspective, which is why I'm wondering if there's decent empirical evidence available.
Originally Posted by Emevas
It's not so much knee stability you're looking at here, but altered biomechanics. Altering the angle/movement of the hip during stance/gait/functional movement necessarily alters the angle of the knee. If you rotate your hip inwards and attempt a single leg squat for example, you'll find that your knee has to collapse inwards to compensate, and you'll probably be able to feel the stress on the inside of the knee. So the problem with glutes is going to be one of chronically altered biomechanics rather than direct stability of the knee joint.
Originally Posted by TheRuss
If we're going to argue for a chronic problem that then manifests acutely (ligament/cartilage damage), I would think that'd be easier to gather good statistics for than the "you're fine, boom, your ACL's gone" model, if only because you could measure the chronic damage rather than just waiting to count reconstructive surgeries.
Originally Posted by PsychoMongoose
Don't get me wrong; if a PT determines that someone has bad hip positioning and weak or inhibited glutes, fixing that is obviously and uncontroversially the right thing to do. A general/prophylactic application, though ("strengthen your glutes to protect your knees"), is a higher bar to meet, though.
I don't mean this to be snarky like it sounds, but where did this idea of "there's a wave of athletes with weak/inhibited glutes" come from anyways?
Originally Posted by Emevas
Indirectly related to the argument, but addresses (to a degree) methodology on activating the adductors, which are said to have a role in preventing and rehabbing knee injuries.
Journal of Strength and Conditioning Research, vol 24, no 10, 2010
"Influence of Hip External Rotation on Hip Adductor and Rectus Femoris Myoelectric Activity During a Dynamic Parallel Squat." by a bunch of d00dz
And here are a few quotes from "Squatting Kinematics and Kinetics and Their Application to Exercise Performance", by Brad J. Schoenfeld...
On the topic of calves and the knee:
"The gastrocnemius has been the primary ankle joint muscle studied in squat performance. It is believed that the medial head of the gastrocnemius acts as dynamic knee stabilizer during squatting, helping to offset knee valgus moments as well as limiting posterior tibial translation."
And about the hammies:
"The hamstrings (biceps femoris, semitendinosus, semimembranosus) are technically antagonists of the quadriceps, opposing knee extensor moments. In closed-chain exercise, however, they behave paradoxically and cocontract with the quadriceps. This synergistic action has important implications for enhancing the integrity of the knee joint in squat performance. Specifically, the hamstrings exert a counter-regulatory pull on the tibia, helping to neutralize the anterior tibiofemoral shear imparted by the quadriceps and thus alleviating stress on the ACL."
The application to knee injury or prevention is, of course, inferred, but it addresses why squatting can play an important role.
Gonna kick some life back into this thread, if y'all don't mind.
Originally Posted by TheRuss
Where did this idea come from? Studies like this might have helped:
Wilson et al. Gluteal muscle activation during running in females with and without patellofemoral pain syndrome. Clinical Biomechanics (2011); 26:7.
"Females with patellofemoral pain demonstrated delayed (P = 0.028, effect size = 0.76) and shorter (P = 0.01, effect size = 0.88) gluteus medius activation than females without knee pain during running. The magnitude and timing of gluteus maximus activation was not different between groups. Greater hip adduction and internal rotation excursion was correlated with later gluteus medius and gluteus maximus onset, respectively."
(40 subjects, all running 10+ miles per week.)
Ott et al. Hip and knee muscle function following aerobic exercise in individuals with patellofemoral pain syndrome. Journal of Electromyography and Kinesiology (2011); 21:4.
"In the current study, we had patients with and without PFPS perform an aerobic exercise and hypothesized it would cause a decrease in knee extension torque and quadriceps activation and an increase in gluteus medius activation in PFPS patients when compared to healthy controls. When PFPS patients were categorized according to change in pain, different muscle responses were observed for the gluteus medius, VMO and VL, during the single leg anterior reaching task. In patients who reported greater perceived pain following the exercise, inhibition of the VMO and VL was observed, whereas patients who reported lower levels of perceived pain following the aerobic exercise had decreases in gluteus medius muscle activity. These results suggest that the gluteus medius may be a source of altered neuromuscular control during exercise."
(40 recreationally-active subjects.)
I can also throw you an RCT pilot study (Avraham et al., 2007) showing improvement in PFPS when hip abductors are incorporated in treatment exercises; a cohort study (Tyler et al., 2006) focusing on hip flexion strength and iliopsoas/IT band stretching showing excellent improvement in PFPS; and the entire curriculum vitae of Christopher M Powers, PT.
Snippets from Powers:
"Greater hip adduction, hip internal rotation and knee abduction are associated with higher levels of pain and reduced function in males and females with patellofemoral pain." (International Journal of Sports Medicine, 2013)
"A review of the biomechanical and clinical studies in this area indicated that impaired muscular control of the hip, pelvis, and trunk can affect tibiofemoral and patellofemoral joint kinematics and kinetics in multiple planes. In particular, there is evidence that motion impairments at the hip may underlie injuries such as anterior cruciate ligament tears, iliotibial band syndrome, and patellofemoral joint pain. (Journal of Orthopedic Sports Therapy, 2010)
Lastly, there's a marvelous international research retreat in 2009 that Powers headed which addressed proximal, distal, and local factors in PFPS. Basically, it's still a complex problem, but it could because of dysfunction in the foot, dysfunction in the knee, or dysfunction in the foot. Dense but fascinating stuff.
Does that help give an idea as to why PT's have started to adopt this multifaceted view towards PFPS and other forms of knee pain?
If anyone wants me to message them the full texts to any of the above (including the supplements and notes to the research retreat), let me know.