Today I was doing more research into tendon adaptation and performance and ran across the abstract below. Without reading too much into the results, this study points out the contribution of the triceps surae (basically the calf) tendon/aponeurosis (I will just say tendon or tendons for the balance of this writing) to locomotion.
I will admit that for many years I have not really understood the full extent of the contribution tendons make to human movement. I, of course, knew that they anchor the muscles to bone thus allowing movement. What I did not realize until a few years ago, and even more so until very recently, was their true contribution to force production. In other words, I used to envision them as essentially passive conduits of the force created by the contracting muscles. As I now know, nothing could be further from the truth.
Tendons are significant contributors to expressed force production. They enhance total force output and make movement more economic by reducing the force requirements of the muscle.
Tendons do not produce force; rather they store and release it through their elastic properties.
This brings me back to a video I recently made with which I hoped to shine a clarifying light on the current mobility/flexibility craze seen in the strength training and athletic world. In short, increased tendon stiffness from training (especially strength training) is nearly universally viewed these days as a negative adaptation. People are told to “correct” it. What very few realize is that the increased stiffness is actually a POSITIVE adaptation assuming it does not get to the point it impedes one’s range of motion for a sport specific task etc.
The increased tendon stiffness, in real world application, results in a greater storage and release of potential energy which directly contributes to work being performed. An example would be when a lifter is bench pressing. Increased tendon stiffness in the pectoralis major will result in a greater maximum pressing ability and greater strength endurance with lighter loads as the elastic component of the tendons is able to store and release a greater amount of force.
So, the take home message is once again that increased tendon stiffness from training is ONLY a negative if it impedes your ability to complete a full range of motion for your given sport or form of exercise. It is, otherwise, a BENEFICIAL adaptation.