Joint mobility

In everyday conversation, “being flexible” and “moving well” are often used to mean the same thing, but exercise science and rehabilitation distinguish between them. Flexibility is the ability of tissues such as muscles and tendons to lengthen passively under external force or gravity. Mobility is the ability to move through that range under your own power and with control.

The key word is “active.” Mobility is not just about how much tissues can lengthen; it also includes whether you can produce force and maintain your position within that extended range.

A common example is raising a leg. Some people can have their leg lifted to ear height when someone beside them supports and raises it, but can only lift it to about waist height on their own. They have good flexibility, but their strength and control have not yet caught up enough to use that range actively. In other words, good flexibility does not necessarily mean good mobility.

The reverse can also be true. Some people have a limited range when someone stretches them, yet can produce force and maintain their position steadily within it. Their flexibility may be limited, but their ability to use their available mobility is solid.

When developing mobility, it therefore helps to combine stretching with practice producing force and maintaining control within the expanded range. Some research also suggests that strength training through a wide range of motion can help improve flexibility to a similar extent as static stretching, so addressing stretching and force production together is a natural approach.

Mobility is not a single quality, but the combined result of several factors.

• Range of motion (ROM): The physical range through which a joint can move. Flexibility and joint structure both play a role.
• Strength: The ability to produce force at the end of that range and at any point within it.
• Stability: The ability to keep the joints and trunk from swaying in unwanted directions during movement.
• Motor control: The nervous system’s ability to coordinate the timing and intensity of activity across multiple muscles to produce movement along the intended path.

All four need to be present for mobility—the ability to “move through that range under your own control”—to be fully developed. It is therefore better to address them together rather than train just one component in isolation.

The two concepts are distinguished in terms of range of motion (ROM). Flexibility is passive range of motion (passive ROM), created by an external force, such as when someone pushes your leg for you. Mobility is active range of motion (active ROM), in which you achieve the same position using your own strength and control. The point of this distinction is that these two measures do not always change together, even within the same joint.

Researchers have also investigated why stretching increases range of motion. One explanation is that muscles physically become longer; another is stretch tolerance theory. This theory proposes that repeated stretching leads the brain to perceive the same stretch as less threatening, allowing you to tolerate a greater angle comfortably. Recent research suggests that stretch tolerance plays the larger role. Either way, rather than treating a particular angle or number as the correct target, it makes sense to judge whether you can use that range comfortably in everyday movements.

“Mobility exercises” is a collective term for exercises that develop the ability to actively move joints through a wide range. The term became popular in fitness settings after the publication of Kelly Starrett’s *Becoming a Supple Leopard*. These exercises fall into two broad groups.

• Methods that apply pressure to muscles: These involve self-myofascial release, applying pressure to muscles with a foam roller or massage ball. Foam rolling and the use of a massage ball are typical examples.
• Active range-of-motion drills: These movements involve actively moving a joint back and forth in a particular direction while also training control.

A growing body of research suggests that, unlike static stretching, both methods can increase short-term range of motion without substantially reducing immediate strength and power, even when performed just before exercise. This effect is explained more by changes in stretch tolerance than by tissue rearrangement: sensory receptors respond differently, so the same stimulus is perceived as less threatening. The effect tends to last for tens of minutes, making these methods useful as part of a routine to prepare for that day’s movement.

There are easy-to-follow mobility exercises for different areas of the body.

• Hips: The 90/90 movement involves sitting with both legs bent at 90 degrees and shifting your body from side to side. See Hip mobility for more.
• Thoracic spine (upper and mid-back): Options include the open-book movement, in which you lie on your side and open your chest by sweeping your upper arm wide, and a rotation performed on all fours with one hand behind your head. See Thoracic mobility for details.
• Ankles: Stand on one foot in front of a wall and slowly move your knee toward the wall. See Ankle mobility for more.
• Shoulders: Stand with your back against a wall and slide your arms up and down. See Shoulder mobility.

The approach is simple. Move slowly through a large range, then engage your muscles and briefly hold at the farthest point. Stay within a pain-free range and breathe comfortably. Consistency is better, even if it is only 5 minutes a day, and these movements can also be used as a warm-up before exercise or when getting up after sitting for a long time.