Read the passage from "Yes, Sitting Too Long Can Kill You, Even if You Exercise."
"Sit less, move more" is what the American Heart Association encourages all of us to
do. But this simplistic guideline doesn't quite cut it, said Keith Diaz, lead author of
the new study and an associate research scientist in the Columbia University
Department of Medicine.
'This would be like telling someone to just 'exercise' without telling them how," Diaz
wrote in an email.
What is the central idea of this passage?