Tendons are fibrous strings that attach muscles to bones. They are not simply inert attachment structures – they have elastic properties that add to the ability of a muscle to generate force. The Achilles tendon, for example, is thought to store as much as 34 per cent of the power output from the ankle.
Tendons are mostly made of collagen bundles and these increase in tensile stiffness, density and thickness with training, but reduce in thickness with limited exercise, making them vulnerable to strain. Tendons take time to adapt because they have a slower metabolism and a less-efficient blood supply than a muscle. They take months, not weeks, to develop.
If you are new to running, you should be aware that repeated tendon stress leads to micro-damage. Tendons may also undergo age-related changes, meaning they are less able to cope with load as we get older. To avoid this, a gradual build-up of running is required. Also, specific exercises to improve the quality of the collagen and its ability to cope with force can help.
It is thought that the higher the training load, the greater and faster the tendons change. We know eccentric loading (lengthening while under load) creates higher force than concentric (shortening while under load) or standard resistance training and so it should follow that eccentric training is best. However, the research has not so far provided a definitive answer. Eccentric loading is beneficial, but we cannot say if it is better than concentric or conventional training. My advice is to mix it up, because running has both eccentric and concentric components to it.
The tendons most at risk in runners are the Achilles; the tibialis posterior, which holds the foot arch up; the anterior shin tendon (tibialis anterior); the hip flexor tendons rectus femoris and sartorius; and the top of the hamstring. What follows is a series of exercises that will help avoid tendon issues if you work them into your training once or twice a week. As with all loading exercises, do not push into pain.
There is some evidence collagen supplementation is useful; so is vitamin C and staying well hydrated. Also, no more than 5-6 minutes of loading is needed for tendon change, but it will take at least eight weeks of work to get the benefits.
Achilles
Eccentric exercise in this tendon, which runs along the back of the ankle to the heel, is well researched. Stand on the edge of a step, rise up onto both feet, shift your weight to one leg and slowly lower over five seconds. Research recommends 3 x 15 repetitions, but I prefer 25, and if you can add some weight (around 10-15kg in a rucksack), then do so.
Anterior tibial/Tibialis anterior
The anterior tibial tendon lies on the inner-front of the ankle, and works together with the tibialis anterior muscle (that runs down the front of the shin) to flex the foot upwards. Heel walking with the foot pulled up is effective, though not as easy to do as you might think. Walk on your heels for one minute in between each set of the tibialis posterior foot turn-in exercises (see below).
Tibialis posterior
The tibialis posterior tendon runs behind the inside bone of the ankle, across the instep and attaches to the bottom of the foot. It is the main tendon giving support to the arch of the foot. Eccentric loading is harder to achieve in this tendon, so I use a combination of concentric and eccentric loading against a cable pulley in the gym or a heavy resistance band. Sit with the band or cable over your forefoot, as shown. Cross the foot over the other and fix your knees together. Slowly turn the foot in and then slowly out over five seconds each way. Do three sets of 12 repetitions.
Hip flexors: Rectus femoris and Sartorius
These tendons are at the top and front of the hip and are frequently injured in runners – they help flex the hips so are integral to the running action. Using a resistance band in a short loop over your foot and fixed under your standing foot, slowly lift the leg up to a high knee position (above left), hold for 30 seconds and lower. Repeat six times with your leg straight (above right) and six times with the thigh rotated out to load the sartorius more. This could also double as your tibialis anterior exercise if you work hard to hold your foot up against the band.
High hamstring tendon
The high hamstring tendon is located high up on the rear of your legs, where your hamstrings meet your buttocks and attach to the pelvis. Lie on your back with your legs out straight and knees bent a few degrees. Push through your heel and lift your bum off the floor, shift your weight to one leg and hold for 30 seconds x 5 on each leg. To make the move harder, you can add a weight to your hips with a dumbbell, as well as lowering your bum more slowly to the floor.
practice in Northampton A 16-week marathon strength training plan Health & Injuries.
