Stability

Even while walking, lifting an object, or standing on one leg, your body constantly makes tiny swaying movements. Stability keeps this sway from increasing and divides the roles between the areas generating force and those holding steady. With sufficient stability, joints do not wobble widely in unintended directions, and force is transmitted precisely where it is needed.

Three components work together to provide joint stability. This framework was outlined by spine researcher Manohar Panjabi.

• Passive components — The shape of the bones, the ligaments, and the capsule surrounding the joint. They keep the joint from separating excessively at the end of a movement.
• Active components — The muscles surrounding the joint. They contract as much as needed at each moment of movement to hold the joint steady.
• Neural control — The nervous system's work of sensing the body's position and movement and deciding which muscles to use, when, and how much.

So stability does not simply mean having strong muscles. The key is for muscles to work together with the right timing and the right amount of effort.

Joint mobility and stability are often discussed together. For example, the shoulders and hips need large movements, while the lower back and knees need to keep movement well controlled. The view that joints needing mobility alternate with joints needing stability throughout the body is widely used in training settings. In this view, the ankles, hips, and upper back (thoracic spine) require more movement, while the knees, lower back, and shoulder blade region require more stability.

However, each joint does not use just one ability. All joints use both abilities together, depending on the situation. In movements such as squats, the two work simultaneously: the hips move through a large range while the lower back holds steady and straight.

In the lower back, stability is sometimes understood as "firmness (stiffness) created jointly by the muscles around the spine." When muscles surrounding the spine, such as the transversus abdominis, multifidus, and erector spinae, contract simultaneously at a low level of force, the spinal segments become firm together, like a single column. Other joints, such as the hips, then handle the larger movements.

For this reason, stability exercises are not aimed at making muscles much bigger. They are closer to endurance training, in which several muscles work together at low intensity for a sustained period. For more details, see Core stability and Core muscles.

• You wobble when standing on one leg — How much you sway while putting on socks or changing your pants offers a clue to your balance and stability.
• Your lower back gets tired first when you stand for a long time — When the trunk's ability to hold steady declines, the lower back can easily become stiff and achy.
• Your lower back arches when you lift something heavy — If the trunk is not held firmly in place, force leaks into the lower back.
• You frequently roll your ankle — This can happen when the stabilizing components around the ankle cannot respond quickly to movement.

• Single-leg standing — Lightly hold a wall or chair and stand on one leg for 20–30 seconds. Once you are comfortable, try closing your eyes or standing on an unstable surface.
• Plank — Support yourself on your elbows and toes, keeping your body in a straight line. Start with the length of time you can hold without your lower back arching, then gradually increase it.
• Bird dog — From an all-fours position, slowly extend the opposite arm and leg, holding your trunk steady without swaying.
• Side plank — Use the muscles along the side of your trunk to keep it straight.

Consistency matters more than the type of exercise. Start with easy movements and gradually increase the difficulty once you can perform them without wobbling. It is best to breathe comfortably rather than hold your breath.