Stop doing sit-ups! Try this one ab exercise for a rock-solid core

You can say goodbye to sit-ups with this bodyweight exercise, which strengthens your core and hips without hurting your spine ...

No more crunches! This trainer’s dumbbell workout takes under 20 minutes and builds stronger arms and abs at the same time

Kill two birds with one stone (dumbbell) in as little as 15 minutes using this trainer's abs and arms strength building workout.