Looseness is another very important element in the practise of Tai Chi and Qi Gong. Without that element the movements are not lively and natural. But looseness should not be mistaken for slackness, all the joints should be loose and relaxed in a connected and coordinated way, keeping the correct alignment of the bodyparts intact.
And this is something very natural as you can see it done by children when they rotate their body with there arms loosely hanging at the side and then being flipped from one side to the other.
So in other words being loose is a very natural thing that we often forget about as we grow up, but the good news is that we can regain it and develop it more and more as we train.
The system of the Wu Style Tai Chi Chuan provides very effective exercises to understand and develop that element of looseness which is very beneficial for the health as it loosens all the structures of the body and dissolves tensions and tightness.