Crunches have long been the go-to exercise for a post-workout ab finisher. Not only are they simple to execute, but you can't deny the burn that comes after just a few reps. Still, as fatigue sets in, ...

View post: Skip the Stairmaster. Celebrity Trainer Shares a Joint-Friendly Cardio Workout to Burn More Calories in Less Time Crunches target superficial abs but may strain the lower back with improper ...