The bird dog is a bodyweight exercise that strengthens the core—more specifically, the abdominal muscles, lower back, butt, and thighs. Since it requires no equipment other than a mat, it can easily be integrated into almost any core strength training routine.
Find a spot with enough space to extend an arm and leg at the same time. Kneel on an exercise mat or other cushioned surface with your knees hip-width apart and hands firmly on the ground, about shoulder-width apart. Engage your abs.
Point one arm out straight in front and extend the opposite leg behind you, forming a straight line from your extended hand to your extended foot. Keep your hips squared to the ground. If your low back begins to sag, raise your leg only as high as you can while keeping the back straight.
Hold for a few seconds, then return to your hands and knees. Keep your abs engaged throughout the entire exercise and work to minimize any extra motion in your hips during the weight shift.
Switch to the other side.
Aim to complete five reps on each side or 10 reps total. Add additional sets of 10 exercises for a maximum of three sets of 10.