Friday, 25 March 2016

Performance Series: 'A'- Frame skiers: Part 1

You are most likely to have come across the term 'A'-frame if you have done a BASI or high performance course.  However, awareness of and ability to correct an A-frame position can have a positive effect on ski performance and help to decrease injury risk. 'A'-frame skiing is a fairly large topic, so I am going to divide it up over the next two weeks. In this weeks blog, I am going to talk about why the 'A'-frame position may occur and next week I will be talking about training methods to help improve this.

An 'A'-frame skier is 'knock kneed'.  They typically have their ankles further apart than their knees, as shown in the first picture below, rather than 'well-stacked' in parallel lines as the second picture shows.

               'A'-Frame position

In medical terms, we call this a valgus knee position (or more specifically Genu Valgum).  A person may be affected on one or both sides.  

In skiing, this position can make it very difficult to stand on the outside edge of the ski, it may cause the skis to diverge and the turn may feel jerkier and less controlled as a result.  It can also make turns in powder a challenge.

From a medical point of view, an 'A'-frame position can increase the strain through the inside of the knee joint, compressing the medial meniscus (inner knee cartilage) and increasing the strain and forces through the soft tissue.  Although there is no scientific evidence for it, some suggest that this position can increase the risk of early onset knee arthritis.

Below, I have discussed some of the reasons that an 'A'-frame posture may occur.

Postural and position awareness

Firstly, simply being aware of this position and aware of how you train off the hill may be a key element in correcting an 'A'-frame posture.  Many people are not aware of having a valgus knee position and why should you be unless you have had a knee problem, a personal trainer or are being treated by a physiotherapist?

If you have been told that you are an 'A-frame skier or if you would like to work out if you may suffer from valgus knees, the first thing to do is perform a double or single leg squat in front of a mirror. Repeat this a few times.  Are your knee caps well aligned over your 2nd and 3rd toes as you repeat this movement?  Do you knees drop inwards?  If so, can you correct this simply through awareness and the feedback of watching yourself in the mirror?

In the pictures below, a single leg squat is being practiced. In the first picture the knee is dropping inwards, however in the second picture this has been corrected.  If you are able to correct this position simply through being aware of where a well aligned position is, repeating this movement in front of a mirror on a regular basis over a 6 - 8 week period often helps to improve the position.   You will develop improved proprioceptive (bodily) awareness and improved motor patterns which should carry over when you put your skis on.

Weak hip abductors and external rotators (muscles which turn your hip out and away from the body)

During assessments of 'A'-frame skiers, one of our main findings is a weakness in the hip abductors and external rotators.  The gluteus medius muscle in the side of the hip is often a major culprit.  As you can see in the diagram below, a weak gluteus medius can cause the pelvis to drop on the opposite side. When this happens, the knee is also forced inwards and will inevitably result in a 'A'-frame ski position.

If you are able to correct your valgus knee position when performing squats in front of a mirror, but with repetitions you are unable to sustain the correction, perhaps a weakness in the hip is the cause.

There is a lot of evidence to suggest that weakness in the hip area can be a large cause of knee pain.  In fact, there are many physiotherapists that only treat the hip when treating patella femoral conditions.  I will talk more about this in the future.

Tight Adductor muscles

Your adductors are the muscles on the insides of your thigh and run from your pelvis down to your knee.  When they are tight, they can pull the femur (thigh bone) in and across your body, thus accentuating the 'knock kneed' position.  Tight adductors are often coupled with weak abductors. 

Tight ITB (iliotibial band)

If you have a weak gluteus medius muscle, this will often be coupled with a tight ITB which is likely to overwork to compensate for the weakness in the hip.

The ITB is a thick band of fasica that runs down the outside of the thigh.  One of its roles is to help stabilise the knee and therefore it is commonly tight in runners, cyclists and skiers from overuse. The ITB is made of thick connective tissue and has a relatively poor blood supply which means that is does not easily stretch.  When it is tight it can pull the thigh inwards and therefore cause skiers to be 'A'-frame.

One of the best ways to improve this fasical band is through foam rolling, however I will be talking more about this in next weeks blog.

Foot over-pronation

If you are a runner or advanced skier, you may well be aware of your foot position. Although the research is mixed as to whether an overpronated foot position may increase injury risk, we do know that it contributes to a valgus knee position. If your foot rolls in, so does your knee.

Figuring out why the overpronation is occurring is key to applying the correct treatment. Often, a progressive program to correct muscle imbalances in the lower limbs is sufficient, other times orthotics or foot beds are necessary.

Hip Joint

Occasionally, an 'A'-frame skier may not be able to correct their position because the cause is inherent within the ball and socket joint of the hip.  Femoral anteverison describes the inward rotation of the hip and this torsion is usually due to someones genetic skeletal make up and is unlikely to respond to treatment.  A physiotherapist should be able to gauge if this may be the cause, although an x-ray is the most accurate way of determining femoral anteversion but would only be required in extreme cases.  Newborn babies are routinely scanned for skeletal hip problems at birth, therefore people are often aware when they have a severe case.  

Osteoarthritis and Rheumatoid arthritis of the Knee Joint

Arthritic conditions can cause the inner aspects of the knee to wear down, which then has an overall affect on alignment and result in valgus knees.  This may be improved by specific exercises or the use of wedges to help the force distribution through the knee joints.  In extreme cases, surgery may be required, but this is usually more of a concern later in life.

Next week, my blog will go into more detail on off the hill exercises to help 'A'- frame skiers improve. Hopefully this will be of interest for not only skiers struggling to correct their position, but also to instructors and coaches who may be looking for ways to improve their clients performance and despite implementing some great drills, just aren't making progress.

We do not recommend that you introduce these exercises without consulting a physiotherapist if you have any current injuries or back issues. We do recommend seeking advise from a healthcare or fitness professional when starting new exercises.  
The purpose of this blog, is to provide general information and educational material relating to physiotherapy and injury management. Bonne Santé physiotherapy has made every effort to provide you with correct, up-to-date information.  In using this blog, you agree that information is provided 'as is, as available', without warranty and that you use the information at your own risk.  We recommend that you seek advise from a fitness or healthcare professional if you require further advice relating to exercise or medical issues. 
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