Eccentric Achilles Tendon Strengthening

The most common injuries related to the Achilles tendon are Achilles tendonitis (microtears in and around the tendon) and Achilles tendon rupture, which is a partial or full tear that results in instant pain and loss of movement.

If you participate in sports that require strong forefoot push-offs—think tennis or basketball—it's important to keep your Achilles tendon strong and flexible. Being sure to warm up before exercise, including stretching the calf muscles and Achilles tendon can help. Read on to learn more about how to strengthen your Achilles.

What Is the Achilles?

The Achilles tendon is a band of tough tissue that runs along the back of your lower leg. It connects the two major calf muscles, known as the gastrocnemius and soleus, to the back of the heel bone.

You need Achilles tendons to not only point your toes but to propel yourself forward in an explosive movement, such as sprinting, diving, jumping, or cycling. It is prone to injury due to limited blood flow and the high tension forces placed upon it.

Common injuries include tendinopathy (pain, swelling) rupture and overuse injury. Athletes and those who are overweight or obese are more likely to experience issues with the Achilles tendon. Achilles tendinopathy affects 2 to 3 in every 1000 patients in general medical practice, but up to 50% of specific active populations such as runners will experience it.

Why Strengthening Is Important

Tendons consist primarily of type I collagen. This type of tissue gets stiffer and stronger under tension. Because the eccentric muscle contractions cause the muscle fiber to generate more tension than either concentric or isometric contractions, eccentric muscle contractions appear to be associated with more significant muscle strengthening, which may protect the Achilles tendon.

Some argue that the benefit may be due to the muscle stretching during eccentric exercise and a corresponding lengthening of the muscle-tendon unit that results in less strain during ankle joint motion and fewer injuries.

While we may not know with certainty if this eccentric exercise benefits from strengthening or stretching, it has been shown to effectively treat Achilles tendinitis when appropriately performed.

How to Strengthen the Achilles

Use the following exercise to strengthen the Achilles. This exercise is based on performing three sets of 15 repetitions on the affected leg twice per day, seven days per week, for 12 weeks. It should be performed with moderate, but not disabling, pain.

1. Warm-up with gentle stationary cycling, walking or marching in place for several minutes.
2. Stretch your calf muscles.
3. Stand on the balls of your feet on the edge of a sturdy box or step, keeping your heels free.
4. Maintain control at all times and slowly lift as high as you can on both toes.
5. Move your weight to the foot on the affected side and slowly begin to lower yourself (this is the eccentric contraction phase) until your heels are just below the step.
6. Shift your weight back to both feet, return to the start (top) position, and repeat 10 to 15 times.

Safety Tips

Achilles pain and injury can be prevented. One of the most common causes is a sudden increase in physical activity. When starting a new sport or exercise routine, be sure to start slowly and gradually increase your efforts.

Tight calf muscles can lead to Achilles tendon injuries as well, so it is vital that you warm up your calves before activity and stretch them regularly to avoid tightness. Wearing the proper footwear for your workout and replacing worn-out shoes can also help prevent injuries.

If you experience stiffness, pain, swelling, or tightness in your calf and Achilles tendon, be sure to stop what you are doing and ease up on your activity going forward. Take time to work on your ankle mobility and calf flexibility and only restart activity when you feel better.

When to Call a Healthcare Provider

Some tightness in the calf or Achilles might not be a concern, but there are some signs that medical intervention is necessary. If you experience pain or swelling close to your heel, especially if it is severe, if you are unable to stand on your affected leg, or cannot bend the foot, see a doctor right away.

Achilles tendonitis occurs when the tendon becomes irritated and inflamed, usually due to overuse. It feels like stiffness and pain along the back of your lower leg, especially upon waking up. It can also cause severe pain after physical activity. The tendon may thicken and swell in response.

An Achilles tendon rupture may make a popping sound when it occurs and you may feel severe pain in your heel or calf. This requires immediate medical attention. When the Achilles tendon ruptures, the tendon fibers tear and separate. This makes the tendon unable to perform normally.

A Word From Verywell

Achilles tendon strengthening will help to prevent the common injuries and complaints that occur in this band of tissue. Eccentric Achilles tendon strengthening exercise is an effective way to boost the health and stability of this vulnerable tissue.

Be sure to thoroughly warm up your entire body before exercise and stretch your calves frequently. See a doctor if you experience pain or swelling in your calf or Achilles tendon.