How to reduce the risk of ACL injuries in skiers. Part 2

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In Part 1 of how to reduce the risk of ACL injuries in skiers we introduced the principals behind ACL injury reduction strategies.  We looked at what the ACL is and what it does.  We also looked at the most common mechanisms that cause an ACL tear in skiers, along with risk factors for injury.

In ‘how to reduce the risk of ACL injuries in skiers: Part 2’ we will be looking at different physical components along with exercises and ideas for training .  Whilst reading this blog, it is important to remember that there is no ‘one size fits all’.  Everyone will be at a different starting point and have different strengths, weaknesses and needs.

Do you remember that in part 1 I mentioned the chap that ruptured his ACL skiing into a tree?  Well, as I said before, no amount of training will prevent some unfortunate accidents occurring.  However, training in a smart way for your skiing gives you the very best chance of staying injury free.

Ideally, you want to start to incorporate the following suggestions into your training program 2 – 4 times a week for 6 – 8 weeks before you hit the slopes.  If you are skiing all season, you can continue with most of these exercises.  However,  you will need to strike a delicate balance between making the exercises progressive whilst not fatiguing yourself before you ski.

Biomechanical positioning and alignment

Being ‘well-stacked’ on your skeleton will put you in a much stronger skiing position. This means that you will use your bones to lever from and therefore you will use less muscular energy.  This will make skiing more efficient and thus reduce the risk of fatigue related injuries.

An example of not being ‘well-stacked’ is in skiers who demonstrate an ‘A-frame’ or knocked-kneed position. This can affect skiers at all levels and can put a lot of strain through the knee joint.  This can also inadvertently make this ACL more vulnerable.

A-frame skier

An example of an ‘A’-Frame )or knock-kneed skier

The ‘A’-frame position may occur due to numerous reason and it is not always easy (or always possible) to correct.  It may arise due to a problem with boot set up or foot position, it may be an inherent position of the hips or a weakness in the gluteal muscles, specifically the gluteus medius.

Regardless of the cause, when you are skiing, if your knee is dropping inwards (‘A’-frame) then the ACL is potentially under extra strain. This position may cause an element of friction of the ACL against a bony notch and over time this may fray and weaken. Imagine a rope that is constantly under tension and rubbing against a rock. All the little fibres will begin to split and the rope frays.  If your ACL is weakened in this manner and trauma then occurs, the chances of the ACL rupturing are a lot higher.

If this position sounds like something that you may be dealing with, an assessment to work out why is highly recommended. In the meantime, many people benefit from strengthening their gluteals and you can try the suggestions below.

Alignment Squats

To check on your alignment stand in front of a mirror. Perform a single leg squat and watch the position of your knee. The middle of your knee should be directly over your 2nd and 3rd toes. If your knee falls inwards then you may need to work on your alignment.

Sometimes, just having awareness of a how to correct a squat is enough to improve it.  If you’ve noticed that your knee drops in during a single leg squat, repeat the movement whilst holding onto something for support.  Now, see if you can squat with your knee in a more optimal position.  You do not need to go very deep to start with but as the position improves you can increase the depth of your squat.

If you can correct this (and not everyone can), then over time, practice and repetition will help you to develop a better movement pattern.  To challenge yourself further stand on an uneven surface such as a wobble cushion or bosu ball.

ACL injuries in skiers

Good alignment in a single leg squat

Monster walk

The monster walk is a great dynamic exercise to get your hips and gluts working.  Place a taught length of strong theraband around your knees, ankles or forefeet.  The further down, the harder it will be – or place band around both your knees and your feet!  Bend your knees so you are in a ‘mini’ squat and side step across a room or along a corridor.  Then repeat in the opposite direction.  Continue this until your hips feel fatigued.  You can vary the depth of your squat but try not to over flex at the waist.

monster walk

Monster walk with theraband resistance

Neuromuscular and proprioceptive factors

Neuromuscular control refers to the transfer of information from nerves to muscles. In other words it is the subconscious connection between the body and the brain. It incorporates balance, strength, reflex responses and functional movement control.  We will break this down further into plyometrics, sports specific drills, strength and flexibility.

Neuromuscular training can help with muscle recruitment. If a skier is well trained they will have better strength and power to produce particular movements. Good neuromuscular control helps to generate joint movement, at the right motion, in the correct alignment at the right time. This has to be discipline specific. For example someone training for bumps will need a different program to a giant slalom skier.

Because neuromuscular training is so person specific, it is best to contact a sports physiotherapist or fitness trainer in order to have a program tailored to your individual needs.

Proprioception refers to the combination of balance, coordination and agility in order to enhance joint position and joint motion. Obviously, the better your balance, the less chance you have of falling and injuring yourself.

You can do a simple test yourself to see if you have good proprioception and balance. Ensure that you are in a safe environment. Start by standing on one leg and maintain this position for at least 20 seconds without wobbling. If this is easy repeat this with your eyes closed.  Again try and stay in a steady position for 20 seconds.  If this is hard to do, then you will need to practice further.  However, if this is easy you will need to challenge yourself with more difficult and more dynamic drills.

Skiing is not a static sport and you will need to practice fairly high level dynamic balance drills to really help make a difference.  You can incorporate single leg squats, wobble boards and wobble cushions into your training.  Lateral or side to side dynamic balance drills are particularly beneficial for skiers.

An example would be side to side touches.  Stand on one leg and reach out to touch the ground to one side of you.  Return upright and remain on one leg, then reach out to touch the ground the other side.  Vary the distance that you reach each side and vary the speed with which you perform the exercise.

Lateral touches

Side to side touches

Plyometrics and Sports Specific Skills

Plyometrics or re-bound training is exercise that is designed to produce fast, powerful movements. Good plyometrics is essential for helping joints to absorb shock. In skiers this is ideal for those that ski in the park, freestyle skiers, variable terrain and bumps where there is generally more impact than on the pistes.  Good plyometric and rebound ability can help the knee joint absorb stresses in such a way as to not stress the ACL.

Plyometric training should be sports specific. Within skiing it should be discipline specific. For example, bumps skiers will need to practice different drills to slalom skiers.

Side to side jumps

A starting point for slalom skiers would be side to side jumps with feet hip width apart (ski distance). Aim to produce a fast rhythmic jump.  You can perform this on the spot, or travel forwards whilst rebounding side to side.  Introduce a small bench to jump over for a further challenge.  Progress to performing this drill on one leg.

Tuck jumps

For bumps training, practising tuck jumps will help with fast hip and knee motion. When practicing tuck jumps think about how you perform them. Symmetrical legs, a tight tuck and a good knee bend on landing will all help to improve plyometric performance.  You will also need to avoid breaking at the waist.  Keep your torso upright as you draw your knees up to your chest.

Muscular strength and recruitment patterns

If you are not physically fit and fatigue sets in then positioning and alignment may falter, which will increase the strain on the ACL and increase the risk of falling. The stronger you are, the better your joints will be able to withstand stresses. Commonly, skiers are very strong in certain muscle groups and weaker in others.

Typically, skiers have very strong quadriceps muscles and much weaker hamstrings. In order for the ACL to work in an optimal position and to avoid an uneven tug of war between these two groups of muscles the hamstrings must be trained. There is also a reflex arc between the hamstrings and the ACL.  The hamstrings help to reinforce the ACL and therefore it is essential that they are strong in skiers.

Two of the main roles of the hamstring muscles are to extend the hip and flex the knee.  When training the hamstrings it is important to work on both aspects.

There are numerous exercises that you can do to strengthen your hamstrings including:

  • Hamstring curls
  • Deadlift variations
  • Kettlebell swings
  • Bridging
  • Nordic hamstrings

I will write about specific hamstring training in a future blog.  However, when you are training your hamstrings, think about doing a variety of different exercises.  Change the resistance and the intensity so that you are doing higher repetitions with lower weights for endurance, and low repetitions with high weights for strength gains.

Flexibility and mobility

Good flexibility and mobility allows the joints to move freely in order to meet the demands of skiing. If joints are restricted it may lead to resistance to movements and inefficient skiing.

Good flexibility of your quadriceps (the muscles at the front of your thigh) is particularly important with regards to the ACL . If the quadriceps muscles are extremely tight they can put a yank through the shin bone which causes an anterior shear force of the knee. Under this stress the ACL is at much more risk of injury.

The jury is still out regarding the science of stretching.  Research is still needed to ascertain when and how often to stretch for the most benefit.  However, I would still recommend stretching for recovery after sports and exercise.

You can stretch your quadriceps in a number of ways, but always make sure that you are warm before you start stretching. The most common way to stretch the quadriceps is to stand on one leg and take hold of your foot or ankle and draw you foot up to your buttock. Take this as far as comfortable. You should feel tension in the front of your thigh but not pain. Make sure you hold this for at least 30 seconds.

You can also stretch you quadriceps dynamically before you ski. To do this step forward on one leg and kick the heel of your opposite leg up to your buttock. Repeat on the opposite side.

In Summary

There is limited evidence for programmes designed to reduce the risk of ACL injuries in skiers.  A lot of my recommendations are based on applying the principals of injury reduction programmes from other sports to the biomechanics of skiing.

For all of the above components to ACL injury risk reduction it is recommended that you seek professional advice from a physiotherapist or trainer. Training is person specific and what works for one individual may be different to the next. If you have had previous leg injuries or if you are currently recovering from injury then it is best to seek professional advise before trying any of the exercises mentioned.

To summarise, for the huge physical, mental, emotional and economic costs it is well worth implementing ACL strategies into pre-season training. Make sure you have good flexibility, especially in your quadriceps, ensure you hamstrings are strong and make sure that you have optimal lower limb alignment.

References:

  • Ettlinger CF, Johnson RJ, Shealy JE. A method to help reduce the risk of serious knee sprains incurred in Alpine skiing. Am J Sports Med. 1995;23:531-537
  • Pujol N, Rousseaux Blanchi MP, Chambat P. The Incidence of Anterior Cruciate Ligament Injuries Among Competitive Alpine Skiers. A 25 year Investigation. Am J Sports Med 2007;35(7): 1070 – 1074

       

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ACL injuries in skiers

How to reduce the risk of ACL injuries in skiers. Part 1

This post may contain affiliate links which means that if you click through to a product or service and then buy it, I receive a small commission. There is no additional charge to you.

Years ago, I wrote an article for a British ski magazine on how to reduce the risk of ACL injuries in skiers.  I had some great feedback, bar one lovely gentleman! He emailed me to ask “are you implying that had I done all your exercises I wouldn’t have ruptured my ACL when I skied into a tree”!  To my credit, I answered him very politely.

Can you prevent ACL injuries?

Just in case you were wondering, it is not possible to completely prevent ACL injuries from occurring.  In fact, injury prevention is not completely possible in any sport and anyone who claims otherwise is talking codswallop!  However, there is plenty of research to support the fact that by implementing certain training regimes the risk of sport specific injuries and injury patterns can be reduced.  I know that I have inaccurately used the word ‘prevention’ when discussing ways of reducing the risk of injuries occurring in the past.  However, as my practice has evolved and my understanding of research has improved I try to select my choice of language more carefully.

Because reducing the risk of ACL injuries is such a large topic, I have decided to publish the blog in two parts.  Part 1 aims to look at what the anterior cruciate ligament (ACL) is and how it functions.  We will identify risk factors and injury mechanisms in skiers. Following this we will explore ways of how you can decrease the risk of an ACL injury when you are skiing.

Part 2 will talk more about the physical factors associated with ACL injury.  It will explore ways that you can train to decrease the risk of injury.  There will be lots of examples of ski specific exercises that you can perform at home.

This blog is applicable to skiers of all levels and abilities. Information regarding ACL injuries is also extremely important for ski instructors.  This is from both a personal point of view and professionally in terms of teaching.

The impact of ACL injuries

ACL disruption is problematic to skiers of all levels, both physically and psychologically. An ACL rupture has a substantial impact on ability to work and earnings, quality of life and day-to-day function. Unfortunately, if you rupture your ACL you may need surgery.  This is usually followed by up to nine months of rehabilitation.

One study carried out over 25 years looked at the incidence of ACL injuries in elite French national team skiers between 1980 and 2005. The data collected showed that more than 28 % of female skiers and 27% of the male skiers sustained at least one ACL injury from a skiing accident. This means that more than a quarter of these competitive skiers suffered an ACL injury! This highlights the need to reinforce the importance of ACL injury reduction strategies.

ACL disruption makes up a large portion of ski injuries. It is every skiers worst nightmare. They fall, they hear a pop, there is a moment of agonising pain and when they try to stand up their knee gives way.  The following signs and symptoms may occur with an ACL rupture:

  • You may hear or feel a pop or snap
  • There is acute pain but this may only last for a short duration
  • The knee swells within a few hours
  • The knee feels very unstable and may give way.

What is the ACL?

ACL stands for the Anterior Cruciate Ligament.

Ligaments connect bone to bone. The ACL is one of the four main stabilising ligaments of the knee. It starts from the front of the tibia (the shin bone) and twists up and backwards to join the femur (the thigh bone).

The anterior cruciate ligament

The ACL

What does the ACL do?

The ACL prevents the shin bone (tibia) moving excessively forward on the thigh bone (femur). This helps to stabilise the knee and allows the joint to bear loads correctly.

How is the ACL injured in skiers?

The ACL is made of tough, fibrous tissue. However trauma to the knee can cause it to tear or rupture.

Twisting, pivoting and strenuous landing movements can all affect the ACL. The following are well recognised mechanisms of ACL injury in skiers.

1- Forward Twisting Fall

A forward twisting fall may account for more than half of all ACL injuries in recreational skiers.

A valgus-external rotation force occurs when catching an edge of the ski when executing turns. This means that the knee bends inwards and twists outwards.

2 – The Phantom Foot Mechanism

This is basically a backwards twisting fall.  It can occur to the leg of the downhill ski during a sudden loss of balance or control. Phantom Foot injuries occur when a skier is off-balance to the rear with their hips below their knees. The downhill knee is subjected to internal rotation (twisting) and bending forces. As a result there is a combination of a strong quadriceps contraction applying an excessive force to the shin bone along with the lower leg stuck in a rigid ski boot in a binding that fails to release.  The strain from this type of fall has to be taken up somewhere and it is usually the ACL which suffers.

This can occur if trying to get up while still moving after a fall, recovering from an off-balance landing, or attempting to sit down after losing control.

3 – The Boot Induced Mechanism

This tends to occur on heavy impact and hard landings when the skier becomes off-balance to the rear. The ski continues to move forward while the pressure of the boot against the back of the leg increases. At the same time, the muscles of the skier’s leg automatically contract to hold the leg in a fully extended position. The leg is unable to absorb the jarring impact and the back of the boot drives the tibia out from under the femur, thereby tearing the ACL.

4 – Collision Mechanism

This occurs when a skier is hit from behind on the lower leg. The impact forces the shin bone forward which causes damage to the ACL.

5 – Catching an edge at high-speed

The inside edge of the front of the ski becomes impacted under snow. The involved limb begins to draw away from the body and rotate outwards while the skiers momentum carries him/her forward. This usually occurs skiing at high velocity in poor conditions.

What should you do if you suspect that you have an ACL tear?

Firstly, seek medical advice. A doctor will usually perform an x-ray on your knee to ensure that there is no bony damage associated with the injury. However, an x-ray will not show an ACL rupture. For this you need an MRI scan, but even a scan cannot always be 100 % reliable.

A doctor or physiotherapist can carry out a series of manual tests to see if they think an ACL injury has occurred. Managing the swelling is extremely important. You can use the POLICE acronym.

Protection. To prevent further damage and to allow the knee to rest to encourage healing you will need to protect the joint.  This is especially true if it is giving way. A knee brace and crutches may be given to you when your injury initially occurs.

Optimal Load. This means starting early rehabilitation so that you can maintain as much strength through the knee as possible.

Ice. Wrap some ice in a cloth. Place it over your swollen knee for 10 – 15 minutes at a time. You can repeat this every couple of hours.

Compression. Tubigrip or an adhesive bandage works well.

Elevation. The higher the better!

ACL injuries in skiers

Manual testing of the ACL

Having a good understanding of your injury will greatly help you manage on the road to recovery. The sooner that you see a physiotherapist and begin rehabilitation, the better the long-term prognosis. It is essential to learn how to maintain muscle strength and regain range of movement as soon as possible.

What next?

ACL surgery is a whole new topic in itself. Not everyone will need an operation. However, in the majority of cases if you are keen to return to skiing, surgery may be advised. However, there are many cases where surgery has been avoided by intensive rehabilitation. Whether or not you should have surgery or manage your knee conservatively is best discussed with you doctor, physiotherapist and surgeon.

There is no evidence to support the need for immediate surgery after an ACL rupture. It is usually preferable to let the swelling settle before operating and this can often take 6 to 8 weeks.

Risk factors for an ACL injury in skiers:

  • Environment – poor visibility and difficult conditions and poor safety awareness.
  • Gender. In some sports, due to anatomical and hormonal factors females are at higher risk than men. However, in skiers this is under debate.  It has been suggested that in recreational skiers, women are more at risk.  However, in competitive skiers, the number of ACL injuries is similar in men and women.
  • Foot position. If you have a tendency to over pronate (feet roll inwards) your knee-joint may be under a lot more strain.  This may put your ACL in a vulnerable position. Good boot fit and accurate orthotics are essential.
  • Inaccurate equipment set up, especially din settings. If your bindings don’t release in a fall then the chances of the ACL rupturing are a lot higher.  It is extremely important not to exaggerate or under-estimate your level of skiing (or your weight) when you are having your equipment fitted.
  • Poor strength and fitness levels.
  • Decreased agility and flexibility.
  • Poor proprioception, balance and coordination.
  • Poor biomechanics and alignment leading to structural vulnerability
  • Muscle imbalances leading to inefficiency and fatigue

ACL Injury Reduction Strategies

There is more and more evidence emerging stating that ACL injury reduction programmes are effective and should be implemented into high risk sports.  However, it is evident that little of this research has been carried out with skiers.  Nonetheless, many of the strategies that have been put into practice in other sports can be applied to skiers in a sports specific manner.

A study in the United States implemented a training programme which focused on awareness and education in skiers.  Strategies included avoiding high-risk behaviour and positioning, recognising potentially dangerous skiing situations and responding quickly to unfavourable conditions. They found that using this program reduced the rate of serious knee injuries in skiers by 62% (Ettlinger et al. 1995).

How to help reduce the risk of an ACL injury?

In this blog we will start to introduce ways of reducing the risk of ACL injuries.  In part 2 we will delve further into strategies that recent research has shown reduces the risk of ACL injury in high risk sports. It is a multifaceted approach that incorporates a number of approaches that work in combination to minimise the risk of injury occurring.

Education and Awareness

As mentioned earlier, education and awareness of ACL injuries and how they occur can largely decrease the chances of them happening. It is important for skiers, especially instructors to recognise and convey the risk of potentially dangerous situations.

Even having an understanding of how to fall in the safest manner can dramatically decrease the chances of rupturing your ACL. When falling, to reduce twisting forces through the knee try to bring your arms forward with your hands over the skis and keep your feet together.  If you can remember to do this, I am impressed!  Despite supporting these recommendations, I know that I would struggle to remember these principles if I was tumbling!

It is also important to avoid attempting to get up while still moving after a fall and to avoid attempting to sit down after losing control. If you do fall, keep your knees bent. Don’t try to stand up until you have completely stopped sliding.

Follow us on instagram or facebook to be made aware of when we publish part 2. Here we will look further at biomechanical factors and how to train to reduce the risk of ACL injury.

* References: Ettlinger CF, Johnson RJ, Shealy JE. A method to help reduce the risk of serious knee sprains incurred in Alpine skiing. Am J Sports Med. 1995;23:531-537
* Pujol N, Rousseaux Blanchi MP, Chambat P. The Incidence of Anterior Cruciate Ligament Injuries Among Competitive Alpine Skiers. A 25 year Investigation. Am J Sports Med 2007;35(7): 1070 – 1074
* Ruedl G, Webhofer M, Linortner I, et al. ACL injury mechanisms and related factors in male and female carving skiers: a retrospective study. Int J Sports Med. 2011;32(10):801-6.
* Shimokochi Y, Ambegaonkar JP, Meyer EG, Lee SY, Shultz SJ. Changing sagittal plane body position during single leg landings influences the risk of non-contact anterior cruciate ligament injury. Knee Surg Sports Traumatol Arthrosc. 2013 Apr;21(4):888-97.

Disclaimer: The purpose of this blog is to provide general information and educational material relating to exercise, physiotherapy and injury management. ALP 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 advice from a fitness or healthcare professional if you require further advice relating to exercise or medical issues.

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