A

Stand a foot away from a wall and place palms on wall at shoulder height. Bend right knee in line with right ankle and step back 2-3 feet with left foot, left leg straight and left heel on floor, feet hip-width apart and toes facing forward. Tighten abs and keep pressing left heel into floor to stretch calf. Hold for 30 seconds, then press hips forward to stretch hip flexors for another 30 seconds [shown]. (If your hips are more flexible, your right heel may need to lift slightly off the floor to get a full stretch.) Switch legs and repeat.

B