Images from: www.hughston.com/hha/a.extmech.htm
Knee pain is relatively common in triathletes. In fact the knee is the area that is most often injured by those participating in triathlon. Which discipline causes the majority of knee injuries? Running. That is not to say that swimming and cycling don't cause knee injuries. They certainly can but relative to running the injury rates a low.
The majority of knee injuries in triathletes are not acute injuries i.e. they are not caused by acute trauma such as a fall, but are the result of cumulative trauma. The injury develops over a period of time due to the failure of the tissues to cope with the load being placed on them over that time period.
The anatomy of the knee is quite complex and although it is interesting I will not go into too much detail today. The majority of knee injuries in triathletes are related to the 'extensor mechanism'. The extensor mechanism is comprised of: the quadricep muscles, the quadriceps tendon, the patellofemoral joint and the patellar tendon. The patellofemoral joint is the joint between the patella (knee cap) and the femur (thigh bone). The iliotibial band could also be considered part of the extensor mechanism and this structure can certainly be a source of knee pain in triathletes.
The most common knee injuries seen in triathletes are: patellofemoral joint dysfunction; patellar tendinopathy; iliotibial band syndrome and quadriceps tendinopthy. This list is not exhaustive. There are other injuries in the knee that can occur such as ligament sprains and ruptures and various forms of injury to the different types of cartilage in the knee but the four injuries mentioned above are by far the most common.
Patellofemoral joint dysfunction (PFJD) is the term used to describe pain in and around the patella. Abnormal loads on the patellofemoral joint (PFJ) cause inflammation in the tissue (synovium) around the patella. Once the synovium becomes inflamed it can be continually aggravated by certain activities. Pain descending stairs is a common complaint. The area of pain is often described as underneath or around the patella.
Patellar tendinopathy is a degenerative process within the patellar tendon. The result is a breakdown in the microstructure of the tendon. The tensile strength of the tendon is reduced and the tendon is unable to tolerate normal loads. The process is reversible with appropriate injury management. This injury is common in jumping athletes such as long jumpers and if often referred to as Jumper's Knee but it also occurs in running athletes and cyclists. The area of pain is often described as immediately below the patella over the patellar tendon.
Iliotibial band syndrome (ITBS) is caused by inflammation around the distal end of the ITB as it crosses a bony area on the outside of the knee called the lateral epicondyle. There is some debate as to whether the pain is caused by friction or impingement. When running the pain tends to occur soon after foot strike when the knee flexes or bends (loading response). When cycling the pain is felt most often during the down stroke when the knee is flexed to around 30 degrees. Pain may also be felt on the up stroke as the knee comes into more flexion. The area of pain is often described as over the outside of the knee.
Quadriceps tendinopathy is a degenerative process within the quardiceps tendon. It is the same process that occurs in patellar tendinoapthy. Again this process is reversible with appropriate injury management. It is the least common of the injuries described in this blog and can again occur with either running or cycling or both. The area of pain is often described as immediately above the patella.
There are a number of factors that can predispose someone to the development of the injuries described above such as: biomechanical faults e.g. over-pronation of a lack of dorsi flexion at the ankle (ability to bend your knee over toe); soft-tissue tightness both in the the thigh e.g. quadriceps and ITB and associated areas e.g. calf, hamstrings and hip region; muscle dysfunction such as weakness in the vastus medialis obliquus(VMO), the calf, trunk and/or hip musculature such as the gluteul muscle group; training errors such as a sudden increase in training load or poor bike set-up.
When symptoms first appear the RICE regimen can be useful particularly with patellar and quadriceps tendinopathy and ITBS. Like all cumulative trauma injuries it is important to determine the cause. For example addressing areas of weakness in the trunk and hip to reduce the load on the knee or making changes to your bike set up e.g. saddle position or cleat position.
Using a foam roller to release tight structures on the outside or front of the thigh can be very useful. Click here to see examples of these exercises.
Strengthening of the gluteal muscles may also be required. Weakness in the gluteus medius (hip abductor) is associated with various forms of knee pain including PFJD and ITBS. Gluteus maximus weakness is also commonly seen in association with knee injuries. Click here to see examples of gluteal strength exercises.
Strengthening of the quadriceps and in particular the VMO is important to improve 'tracking' of the patella. When performing any quadriceps strength exercise thinking about using and looking at the VMO in a mirror can help activation of the muscle. Click here to see examples of quadriceps strength exercises. A specific form of strengthening has been shown to help patellar tendinopathy. This is called eccentric loading. I won't go into this in detail in this blog as it is already pretty long!
The muscles of the trunk are also very important and a reduction in the strength of the side flexors of the trunk has been shown to be associated with PFJP. Strengthening of the trunk musculature may therefore be required in some people with the knees injuries outlined above. Various abdominal strength exercises, including exercises for the side flexors, can be seen here.
Recognising training errors is very important. Sudden changes in training load such as an increase in mileage or an increase in intensity with the introduction of hill training or speed work or 'over-gearing' on the bike can lead to injury. You should introduce such changes gradually and only when you have built adequate fitness to do so. A training diary should help you recognise such errors and I well thought at training plan should help you avoid them!
Of course everybody is an individual and each individual's injury will have different contributing factors. If you have an ongoing injury you should seek help from a trained professional to help determine the cause of your injury and how to manage it properly. The tips above are an overview of some management strategies for the injuries described above. They are equally good preventative strategies if you do not have a knee injury and want to try remain injury free.
I hope that was interesting and useful. Tim (LFTC Coach)