According to a recent article in a running magazine, ankle abduction increases Achilles tendon strength. However, this statement is not supported by anatomy or kinesiology. It is well known that the Achilles tendon is involved in the push-off phase of the running stride but not in a sideward (abduction/adduction) foot movement.
According to the article, in order to strengthen the Achilles tendon you lie on your side with the leg to be exercised on the top. You place an ankle weight around the ankle and position you foot so that your heel and toes are in a straight line parallel to the floor in a non-support state. You then tilt the foot in a subtle move, moving the foot only about 10 degrees. However, since the ankle weight is up around the lower shin above the ankle joint it places no resistance on the foot movement. The range of movement is very small and involves mainly the peroneal muscles located on the side of the shin.
Since the movement occurs in the foot itself, not the ankle joint, how can this strengthen the Achilles tendon? This is never explained. Thus the exercise has some value but the role that it plays in running and in strengthening the Achilles tendon leaves much to be desired. If coaches believe that this action strengthens the Achilles tendon, it is very likely that it may lead to injury because the Achilles tendon is not strengthened.
According to the article, to prevent Achilles injuries it is recommended that you increase the range of motion in your entire leg. How increasing range of motion will prevent injuries is not explained. Neuromuscular coordination, and especially strength and running and cutting technique are far more important than any stretches that can be done. The key is to stretch and strengthen simultaneously or consecutively; not merely stretch.
Exercises such as the heel raise (calf raise) especially when done through a full range of motion, are excellent for strengthening the Achilles tendon. Ankle abduction/adduction involve the Achilles tendon only tangentially. Strength exercises in these actions are great for developing the muscles on the sides of the ankle which play a very important role in preventing ankle sprains and strains.
However, to strengthen the muscles you must do exercises in which there is resistance in the abduction/adduction movement. For these actions using the Total Athlete System™ to provide resistance has been found to be very effective. In addition it makes execution much easier and simpler.
The bottom line is that you should do exercises specific to the main and auxiliary functions of the support structures. This is the key to injury prevention and to enhancing your ability to use the ankle in many different activities.