
Movement basics
Bird dog practice is about controlling a reach from hands and knees. Lifting the arm and leg higher is less important than keeping the movement organised.

Place a mat on a firm surface and establish a comfortable hands-and-knees position. The hands are broadly beneath the shoulders and the knees beneath the hips, but adjust with an instructor if that position does not suit you. Spread the contact comfortably through the hands and keep the neck in line with the trunk.
Check the mat for slipping and make sure the reaching hand and foot will not meet a wall or furniture. If the position is painful at the wrists or knees, do not assume you must tolerate it because no weights are involved. A different supported exercise may be more suitable.
Start by sliding one foot backwards along the floor or reaching one hand a short distance, leaving the other limbs supported. Notice whether the hips shift or the torso turns. Return to the starting position before changing sides. This makes the direction of the movement clear without immediately asking for balance on two contact points.
When that is manageable, an instructor may introduce a small lift of one limb, then an opposite arm and leg reach. Extend away rather than trying to raise the foot towards the ceiling. A high leg lift can encourage a large back arch, while an overreaching arm can shift the whole body sideways.
Keep the range short enough to continue breathing and return with control. Pause to rebuild the base if the knees or hands have moved. There is no need to bring the elbow and knee together underneath you unless that is a separately taught variation; adding it changes the task and can make a simple practice unnecessarily confusing.
Place the hand and knee back quietly rather than dropping them onto the mat. If the return becomes hurried, reduce the reach or finish the set. A short successful attempt tells you more than a long hold maintained by twisting away from the intended position.
Record the version you used, such as one foot sliding or a short opposite-limb reach. Bird dog practice is not a diagnosis of core weakness or a treatment for unexplained back pain. Stop if pain or concerning symptoms appear, and seek appropriate advice. You can retain a simple version as part of your routine without making unsupported longer holds the inevitable goal.