What is the Achilles tendon?
The Achilles tendon is situated above the heel and forms the lower part of the calf muscles. It is a continuation of the two calf muscles, the gastrocnemius and soleus muscles, and it attaches to the heel bone.
It is the strongest tendon in the human body and must withstand great forces. Its function is to transmit the force produced by the calf muscles to lift the heel and produce the push off during walking, running and jumping. The Achilles can produce force of up to seven times body weight. This shows just how much force it has to withstand during sporting activities, such as sprinting, jumping and turning.
Understanding terms for Achilles tendon injury
Achilles tendinopathy is a common sports injury. It's caused most frequently by overuse. You might be more familiar with the term 'Achilles tendonitis'. However, in the absence of inflammation, tendinopathy is the more appropriate term.
Until medical examination determines if there is Achilles degeneration (tendonosis) or inflammation (tendonitis) the condition is referred to as tendinopathy.
Achilles tendinopathy is characterised by degeneration (tendonosis) of the tendon, often without an inflammatory response. The degeneration means that the tendon does not have the usual tensile strength and may be liable to rupture during continued sporting activity. However, before you get alarmed, this is very unlikely.
SIGNS AND SYMPTOMS
· Symptoms usually come on gradually. Depending on the severity of the injury, they can include:
· Achilles pain, which increases with specific activity, with local tenderness to touch.
· A sensation that the tendon is grating or cracking when moved.
· Swelling, heat or redness around the area.
· The affected tendon area may appear thicker in comparison to the unaffected side.
· There may be weakness when trying to push up on to the toes.
· The tendon can feel very stiff first thing in the morning (care should be taken when getting out of bed and when making the first few steps around the house).
· A distinct gap in the line of the tendon (partial tear).
The causes of Achilles tendon injuries
Overuse and changes in training
Inflammation/strain of the tendon is usually caused by overuse – for example, frequent jumping in volleyball, netball or basketball. It is often also caused by a sudden increase in certain types of training, such as hill sprinting or track running, particularly when running in spikes.
Tendinopathy can also be associated with ageing. Our ability to regenerate damaged tissue decreases as we age and the quality of the tendon deteriorates. However, the better news is that sensible training can actually strengthen all our soft tissue (tendons, ligaments and muscle).
Tight calf muscles
Tightness in the calf muscles will demand greater flexibility of the tendon, which inevitably results in overuse and injury. Biomechanically, the tightness can reduce the range of dorsiflexion (toe up position) in the ankle, which increases the amount and duration of pronation. This problem is known as overpronation.* This reduces the ability of the foot to become a rigid lever at push off and places more lateral and linear forces through the tendon. This imbalance can translate into altered rotation of the tibia (shin bone) at the knee joint and, in turn, produce compensatory rotation at the hip joint with subsequent injuries to the shin, knee and hip.
Lack of ankle stability
Lack of stability around the ankle joint can also be a contributory factor, as recurrent ankle sprains appear to be associated with a high incidence of Achilles tendonopathy.
Wearing the 'wrong' shoes
Wearing shoes that don't fit or support the foot properly can be a major contributing cause of Achilles tendon injury.