How does the knee work?
Knowing the anatomy of your knee can help to develop a greater understanding of how running affects the joint.
The primary movements of the knee are flexion and extension (bending and straightening).
It is a complicated joint, and following is a basic outline of the tissues and structures in and around the knee.
- Bones - There are four bones that make up the knee joint, including the femur (thigh), tibia and fibula (lower leg), and the patella (your knee cap)
- Cartilage - A coating of hard, shiny cartilage on the end of the upper and lower leg bones that allows them to glide over one another
- Meniscus - The C-shaped, spongy cartilage in between the upper and lower leg bones that helps to stabilise the joint, and provides cushioning while you run
- Ligaments - There are 4 key ligaments that hold the bones together and stablise the joint. These include the medial and lateral collateral ligaments (on either side of the knee), and the anterior and posterior ligaments (inside the knee)
- Bursa - There are a number bursa in the knee, which are fluid filled sacks that help the knee move smoothly
- Muscles - There are numerous muscles in and around the knee joint to make it move. Tendons connect muscles to the bones in your knee
Running and your knees
Your knees do take a lot of pressure and impact while running, yet the affect can be positive or negative depending on a number of variables. Factors such as body weight, running technique, shoe selection, running surface, running speed and body structure can vary greatly amongst runners.
The various structures and tissues of the knee joint will also be affected differently by running. For example, the fact that running is a weight-bearing exercise may help to strengthen the bones and prevent osteoporosis, but it may also wear down the meniscal cartilage over time, and reduce its shock absorbency.
The research
A study published in the Archives of Internal Medicine compared the functional capacity of 284 runners with a control group of 156 non-runners every year for 21 years. A number of functional tasks were assessed, including walking and routine physical activities.
It was found that both male and female runners’ maintained significantly lower disability levels than those of the control group at all time points throughout the study. The researchers concluded that participation in vigorous exercise such as long-term running is associated with less disability over a long period of time.
While not looking specifically at knee injuries, this study shows that people who run regularly can enjoy a greater quality of life over the long-term compared to people who don't run.
Knee protection tips for runners
The impact of running on the knee joint differs greatly amongst individuals, but there are strategies that everyone can adopt to minimise any damage.
- Manage your weight - Maintain a healthy weight if you are a regular runner. Progress gradually from walking to running if you are attempting to lose weight
- Use soft surfaces - Make sure some of your running training is performed on softer surfaces such as grass and sand. Deep water running (while wearing a buoyancy vest) is also a challenging workout that places minimal stress on your knees
- Don't be just a runner - Make sure to include other cardiovascular activities in your training program, such as swimming, paddling or cycling. This can maintain your fitness while giving your knees a break from the impact of running
- Choose good shoes – Look for shoes specifically designed for running that provide good cushioning. It's also important to be aware that shoes lose their shock absorbency over time, so replace them regularly if you are clocking up a lot of kilometres
- Get coached - A running coach can examine your technique, and make suggestions that can prevent injury and potentially improve your running efficiency
- Don't ignore pain - If you are experiencing knee pain, or have any injury concerns, seek professional help. A physiotherapist can diagnose problems and help to prevent future trauma
- Strengthen and stretch your leg muscles - By strengthening and stretching the muscles around the knee, you can increase stability and prevent injury