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The Hamstrings!

The hamstrings are one of the most misunderstood muscles in the body and the explanation of them shortening when we bend the knee or lengthening when we straighten the knee is a huge simplification. To also view them simply as a sagittal plane beast does a disservice to the power that they hold in other planes of movement.

The first question is why are there three and why do they attach in different places?  The attachment of the biceps femoris on the lateral fibula straight away gives us control in the transverse plane. As the lower leg goes into internal rotation the hamstring is able to eccentrically control this motion.  This is similar to the gluteal attachment on the femur that allows it to control hip internal rotation. If we look at the universal function of gait and how much of the gait cycle is spent in internal rotation, due to ground reaction and gravity, it becomes easy to understand why.

The semimembranosus and semitendinosus are on the medial side of the femur attaching into the pes anserinus and onto the medial tibia. From this position they will have much more control of external rotation of the lower limb, either femur on tibia or tibia on femur. If we look at the pathomechanics of ACL injuries for example, the ability to control real femoral internal rotation, thus creating relative external rotation at the knee, is hugely important. Add to this the eccentric control that these muscles will exert on valgusing of the knee, especially with its close proximity to the MCL, we can see the multi plane importance of having these two distinct portions of the hamstrings. In fact should we even lump them together as a single entity??

The might Gary Gray described them as the like the reins of a horse which is a pretty accurate description.  This multi dimensional ability though is rarely noted.

The fibre arrangement remains fairly longitudinal in the sagittal plane. This gives the unique ability to control the range of movement through the other planes. Reduced ability for the fibres to move and lengthen in directions away from the fibre arrangement gives it an inherent stiffness to control motion.  A function related example of this would be how the hamstrings can help control foot pronation through slowing down tibial motion in the frontal and transverse planes at the proximal end.

The fact that the pelvis and the tibia/fibula are both connected to the hamstrings mean that the hamstrings can lengthen when the knee is bent and shorten when the knee is straight. This is all dependent on which section is rotating faster, something that is key to a bi-articular muscle. This means that if the tibia is rotating forward faster than the pelvis then the hamstrings will lengthen. We see this in the front foot phase of gait. The tibia’s distal end is rotating posterior while the superior portion of the pelvis rotates anterior. The tibia closest to the ground has to deal with more force so is rotating quicker creating knee flexion but lengthening of the hamstrings. If the pelvis rotated faster we would spend a lot of time looking at the floor!!! Add into this the anterior translation  of the femur due to gravity and connection to the tibia and we also get a lengthening force on the hamstrings at both the distal and proximal ends.

Equally during the up phase of a squat if the pelvis is rotating posterior faster than the anterior rotation of the distal section of the tibia then we will get shortening of the hamstrings, even though the knee is extending!

The two attachments of the hamstring can be important for understanding hamstring injury.  Many times we see hamstring injuries as lower limb dominant. However a top down drive e.g. pelvis driven, can make a huge impact. If the hamstrings are already under a large amount of tension as we may see during swing phase (large hip flexion of swinging leg) of sprinting. Then any additional tension caused from movement of the head affecting the pelvis may be too much for the hamstrings to handle.  This could be more sagittal plane tension or rotational tension from looking side to side.

In the video clip below we see Fernando Torres as he is sprinting for the ball.

[youtube=http://www.youtube.com/watch?v=d6rhDpELsSg]

He is looking behind him.  This would create some posterior rotation at the pelvis. As we drive the leg (femur) up into hip flexion this posterior rotation would reduce force created through additional eccentric tension on the hamstring that is generated from the anterior rotation of the tibia of the swinging leg. The problem comes when the ball drops and his head comes forward creating more anterior rotation of the pelvis. Now the hamstrings are being lengthened in opposite directions from both attachments. Under extreme force such as sprinting this can cause the hamstring to close down to resist this extreme force. The tissue confused from a proprioceptive standpoint and unable to lengthen will be at far greater risk of being damaged.

So why is it important to know all this about the hamstring?? Well it helps us create an authentic strategy with which to treat and train the hamstring. If the hip or ankle lacks internal rotation and therefore does not allow the hamstrings to lengthen in the transverse plane, then by understanding this need for multi-plane flexibility, created in different ways, we can factor this into our programs or techniques we use.

 

 

 

 

 

 

 

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Knee pain-Patellofemoral. A functional approach.

Knee pain is very, very common. Although there are many types of knee pain affecting the various bursars, tendons and ligaments in that area, one of the most common is patellofemoral pain.

Rather than delve too deep into the minutia in this blog post it maybe much better to have a conceptual understanding of what is needed for successful patella femoral mechanics.

The patella is attached to the femur and tibia via the patella tendon.  In fact it sits in the groove or Condyles that are both medial and lateral on both bones. This means that for successful movement of the patella, these grooves need to stay pretty close. A great way of describing it would be “in sequence”.  Otherwise the patella can smash into the groove causing pain.

We have two pretty important bits of the body attached to these two bones.  Namely the hip which attaches to the femur and the foot attaching to the tibia. That means the sequencing of the grooves can be affected by excessive movement or limitations in movement at either end, the hip or foot.

A common approach is to try to limit the movement at the hip and foot by tracking the knee in the sagittal plane, in effect reducing the variability of motion. The wondrous nature of a ball and socket joint is the huge freedom and variety of movement it gives us.  In fact this freedom and variety could be described as tri plane. An attempted reduction of motion into the sagittal plane will reduce the load to the hip musculature that displays a distinct tri plane nature. Look at the glute and its oblique fibre orientation. Without frontal and transverse plane motion of the femur it will not work effectively. In fact the glute will control the femurs motion into adduction and internal rotation.  Deviations away from the sagittal plane, that occur frequently in functional weight bearing movement, of knee valgus (femur adduction) and femoral internal rotation will need to be slowed by eccentric activation of the glute and hip musculature. This maintains the optimum sequencing between femur and tibia for healthy patellofemoral mechanics

Equally the operation of the foot will affect the sequencing of the tibia. This will also disrupt the patella in the groove. Using gait as an example (and universal function) a rearfoot or forefoot varus will have an acceleratory effect of the tibia following the foot into pronation, creating increased tibial internal rotation and abduction. The sequencing of pronation will also affect the sequencing of the patella femoral mechanics. Late rearfoot pronation will decrease the external rotation of the tibia that along with femoral external rotation keeps the grooves closely sequenced. In fact we may get opposite rotation of femur and tibia. The patella attached to both, as my friend Gary Gray says, “gets caught in the middle with no place to go’.

A lack of motion in sagittal plane such as ankle dorsi flexion may also increase pronation affecting the knee.  This is why people may complain of feeling their knee more when using the stairs. Increased dorsi flexion is required when ascending or descending the stairs. If this dorsi flexion is not available at the talo-crural joint the body may use increased pronation at the Sub-talar and mid-tarsal joints to create more flexion. This increases the frontal and transverse plane forces on the tibia and therefore patella. So increasing the sagittal plane demand as traditional exercise aimed at dealing with patellofemoral mechanics does, may actually cause an increase in the motions that cause pain! An understanding of why dorsi flexion maybe limited could be a more successful approach rather than just try to force more sagittal plane knee motion!

Functional tri plane assessment of both of the hip and ankle are required to understand what maybe causing knee pain rather than generic one size fits all exercise. So many structural foot dysfunctions are present in the general population that without understanding functional biomechanics and structure we cannot effectively treat these problems. A knowledge of how the knee acts when weight bearing rather than just on a plinth is vital as tri plane motion occurs mainly when weight bearing.

Something that always confuses me is the dissociation between foot pronation and knee motion. We classify pronation as movement into dorsi flexion, abduction and eversion and is well documented. This will create tibial internal rotation following the talus. This tibial motion connected to the femur will create internal rotation of the knee. How then can the knee work as a simple hinge joint when weight bearing moving exclusively in the sagittal plane??? Equally the abduction of the tibia at the distal end will result in the proximal end falling in towards the midline of the body creating a valgus at the knee. Again how can we see the knee simply as a hinge???

It is vital that close association of both the femur and tibia occurs in all 3 planes for functional success. This means assessing the foot and ankle in weight bearing and dynamic positions! At Cor-kinetic we always use this thought process when dealing with these types of problems!

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Its all about practice!!

I am writing this sitting over looking a beautiful bay in Crete. I now know why writers such as Hemingway and Greene got inspiration from tropical surroundings! Although I cannot rival their writing I will offer you a window into my soul (for what it is worth)!

One of the books I chose to bring with me was Bounce by Matthew Syed. Bounce is really about practice vs innate talent. It has very much struck a chord with me and given me both positive and negative thoughts on the subject of practice.

In the book Matthew talks about the formula for becoming an expert. This has apparently quite accurately been put at 10 years. In fact with an average of 1000 hrs practice per year this gives us the figure I have oft heard quoted of having to put 10 000 hrs in to become an expert. This reminded me however of a quote oft used by my friend Christian "have we had 10 years experience or 1 year 10 times??". So really an expert should have grown the knowledge they had originally adding to it as they practiced.
The fitness industry is a wonderful thing. It allows us to practice what we love doing daily. One of my students turned round to me and said "I have learned so much from the clients recently". I found this a beautiful comment. He was the expert in the relationship with his client but still found wonderment in how much he got outside of the financial transaction. That is the mark of someone who will continue to learn and grow into an expert. His desire to practice is admirable.  Something that I find invaluable in teaching is still treating and training on a daily basis. The more people you work with the more you learn and the more you can pass on. I think this side of what I do is integral to all the others and reminds me of why I have a passion for this business. All of the people I have learned from and respect in the industry have something to pass on from their 10 000 hrs. In fact this is what has driven them to educate as it has shaped there understanding of the body, adding to what they know rather than just passing on what they have learned elsewhere.

I certainly think that this reduces the number of experts in the industry. Learning something does not make you an expert. Practicing and adding to it year after year does. In fact I think that it would be strange to be able to follow a training system for so long and not experience things for yourself that would lead you to adapt or change it with your own personal experience. Many so-called experts seem to have very little personal opinion (Some would say I have far to many opinions!!) born from only educating themselves via one route or person, that means that their expertise is not from personal experience but from another. If this still makes you an expert or not I am not sure however! That is always in the eyes or ears of the individual making the judgment.

I for one will continue to try to add to my 10 000 hrs although I would regard myself as no expert! I daily still feel dumb when confronted with the wisdom of others but this I think is healthy as he who thinks he knows all probably knows nothing anyway!

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