I would assume but am not completely sure..
A. There is no resistance involved if you are swinging your arm
Answer:
Because it helps kill germs.
Assess flexibility
Trunk rotation is the most common static flexibility assessment.
B . It is completely normal . However if you are experiencing extreme pain stop and consult your doctor . Also if you are prone to any kind heart disease let someone know where you are when exercising or better yet let them be at your side at all times .
