Respect the skeletal structure and function
You have to move the body and find that sweet spot, not too tense, not too relaxed
If you are tense you can't play but you also can't when you are relaxed, so..?
"If you use relaxation to cure tension you replace one problem with another"
Standing up frees up your forearm and therefore there is less tension
you better find another way of playing it
So what we are looking for is good kind of muscular tonus not plain old bad kind of tension
Many muscles in the hand need to be developed to make the hand functional
Being elastic without being tense
It affects the sound as well as induces tension in the wrist and forearm
Also, how to free up shoulders from tension
Alan is explaining how to get rid of unnecessary tension in the thumb
Alan talks about several different technical concepts, joined thumbs, tension vs tonus..see Points of Interest for more details