There is a type of training, the name escapes me, which is about loading the tendons and the muscles, the muscle with significant contraction and expansion, the tendon with just a minor amount. like connecting two stones with a rubber band. the rubber band stretches when you move one stone, then pulls the other stone along.
It's used amongst other things for training Basketball and Volleyball players to jump. An example would be doing squats with a medicine ball, but not stopping at the bottom, instead dropping, then springing up just an instant before you reach the bottom...
Thus, the tendons stretch, then recoil, as the muscles do their more significant effort.
Pak Mei trains using some similar techniques, and generally putting the added load is said to strengthen and increase the tendons due to this load. Not sure, never cut open a Pak Mei guy, yet, to check out the tendons.....
There is also a type of training that involves a slight shaking of the arms and hand, kind of like the visual of hard isometrics, but in a very relaxed manner, my mate calls it the Parkinsons Technique. What you are doing is bouncing your 'in and out' and bouncing your muscles and arm back and forth. just millimeters. Its about control, relaxation and reflex. I suspect that has some effect on the tendons too. I've seen similar in Tai Chi, something about sparrows maybe? Or is the Ma Jong?
Guangzhou Pak Mei Kung Fu School, Sydney Australia,
Sifu Leung, Yuk Seng
Established 1989, Glebe Australia