Ligaments and tendons are like cables, and the collagen molecules are just like wires in the cable.  Envision taking a 10,000 pound rated steel cable, made of a bunch of little wires, and hanging a 10,000 pound weight from the cable.  Then get a wire cutter and start cutting wires.  You will cut several without anything ‘happening’, since the cable is probably a little ‘over-engineered’.  And you are a little ‘over-engineered’ when it comes to collagen molecules in your ligaments and tendons.  You generally have more than you need to hold the considerable loads that these structures hold without stretching.  But you will cut that one wire, and the cable will begin to sag and ‘give’ a little.  You will cut a few more wires, and the cable will sag further.  In this weakened state, 10,000 pounds just exceeded the ‘loadbearing’ capacity of the cable, evidenced by it beginning to stretch.  Or, your normal body loads may exceed the weakened load bearing capacity of a ligament or tendon, evidenced by that stucture beginning to stretch.

Now, as your ligament or tendon begins to stretch abnormally, what about all those fragile little nerve fibers that live inside the structure?  Can you see this new ‘stretching’ damaging these small nerve fibers?  Can you then see the structure becoming ‘tender’, because when you press on the structure, you are now pressing on damaged nerve fibers?  Can you see these fibers firing nerve impulses into the nervous system, which might show up by affecting muscle function, by causing ‘referred symptoms’ that are ‘felt’ in other locations, or by causing other phenomena, like headaches?  This simple concept is the key to unlocking an understanding of many body aches, pains, and dysfunctions.