Usually the attacker suffers more pain from the outside defenses. The defender should aim the middle of his forearm to strike the attacker on his wrist in a speed greater than the speed of the attacker in an angle of slightly more than 90 degrees while toughening his forearm muscles before each defense.
For people that do not aspire to become Shaolin monks, the one in the attacker role could wear protective sleeve or inverted ankle brace on the forearm that can be purchased in a surgical supply store.
That way he can be dedicated to attack in full force and speed without suffering the consequences. But if you do wish to condition the calcium percentage in your forearms over years of weekly training, suffer the consequences then.
Just conditioning your forearms to take punches is not the essence of Hand to Hand Combat. In reality you counter attack with the first block and stop blocking at that point.
So it is good to develop and hone your instincts but there is a point when they are honed and your 360 then becomes a bone conditioning technique. If this is the case, you should probably ice your forearms when you get home. If you are suffering from easy bruised skin, perhaps you need to use some sort of padding.
Finally, it is much better than taking a punch in the softer parts of your body or vital organs or soft tissue pressure points.
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