WORTHLESS EXERCISES YOU PROBABLY DO

Overrated: Crunches

This gym-class standard needs an update: According
to research from San Diego State University, the
traditional crunch is the least effective strengthener
for both the rectus abdominus (6-pack muscles) and
the obliques (waist muscles). What's more, because
sit-ups require more strength from front ab muscles
than obliques, this move can create a strength
imbalance in the core -- setting you up for back
problems.