Bird Dog spares the spine of high compressive loads and targets not only the lower-back muscles but also works the hip extensors, like the glutes and the hamstrings.
Begin on all fours with your hands directly under your shoulders and your knees directly under your hips.
Pull your abs into your spine. Keeping your back and pelvis still and stable, reach your right arm forward and left leg back until they are parallel to the floor. Don't allow your pelvis to rock side to side as you move your leg behind you. Focus on not letting the rib cage sag toward the floor. Reach through your left heel to engage the muscles in the back of your leg and your butt.
Return to the starting position, placing your hand and knee on the floor. Hold for six to eight seconds.
As you begin to progress, add a rep to each set.
Set one: four reps with a 10-second hold. Rest for 30 seconds. Repeat on opposite side.
Set two: three reps with a 10-second hold. Rest for 30 seconds. Repeat on opposite side.
Set three: two reps with a 10-second hold. Rest for 30 seconds. Repeat on opposite side.