Why tighten muscles at punch contact if it reduces impact force

[Skhandelwal]

1.
How to do that?

2. In a punching site...I read that we should do the whip motion when punching...but at the point of contact...should tighten all our muscles...why doesn't that reduce the impact force?

3.
I get the whole video but by the end(it is only a minute long), why does the ATP split; ADP and Inorganic Phosphate bind to Actin? And why does Calcium sticks to the ATP split attached...aka Tropomyosin and Troponin Complex?

 

[Moonbear]

1) Take a good acting class.
2) Without any explanation of what you mean by a whip motion, which muscles you mean, or anything else, how do you expect any answers?
3) Try looking a bit further than youtube for your biology knowledge (I would have hoped this was obvious).
http://www.mpimf-heidelberg.mpg.de/~holmes/muscle/muscle1.html
http://instruct1.cit.cornell.edu/courses/biog105/pages/demos/105/unit10/muscles.html
http://www.ebsa.org/npbsn41/intro_muscle.html
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Muscles.html

 

[Astronuc]

For maximum effect (maximum force/energy transfer), one wishes to achieve maximum speed or thrust, so only the muscles responsible for the motion need to be contracted. At contact the remaining muscles are tightened in order to push into the object being struck and to provide a rigid support structure of the arm to minimize recoil, which would reduce the force/energy transfer.