Pretty Sure He Is Not Using That Machine Correctly

Wilcox loves to work out, and Chelsea likes to work out.  Woody knows that there are people who work out and lets face it we're pretty happy Woody doesn't hit the gym.  Why?  Because Woody would be this guy.  This footage was filmed at a gym in Shanghai, China by onlookers who were left confused by the man's exercise drill. Who was the guy who showed him how to do this the first time?  What muscle group is he working out?  In the strange clip, the man can be seen on all fours and thrusting his pelvis forward rapidly and repeatedly.  We want to try this the next time we hit the gym...just to see the look on people's faces!!!