Does shadow boxing improve upper strength?

i was talking to a friend and he said that shadow boxing can help to improve upper body strength, i know the basic idea of what shadow boxing is but what can i do to make it effective?|||If your 90 years old shadow boxing is a warm up or finishing exercise but must be done properly to avoid bad habits|||it doesnt improve upper strength. just improves technique and hand speed.





if you want to move forward then use this thing


http://uk.youtube.com/watch?v=KacShxlxQQ...|||Depends on how tough your shadow is :-)


|||hand speed, technique and movement