Kneel with knees hip-width apart, forearms on floor, elbows in line with shoulders, hands clasped. Extend legs back, balancing on balls of feet and forearms, and contract abs.

Keep hips square and abs pulled in as you drop one knee to the floor, then straighten leg. Drop the other knee to the floor; straighten leg. Alternate knee drops for 16-20 reps (each rep is one leg). Strengthens abdominals, focusing on obliques.