“Strength” and “stability” are core concepts in physical therapy, and ones we reference often with our patients. However, as the terms are sometimes used interchangeably, we realize that many patients don’t really know the difference between strength vs stability and the interplay between these two physical attributes.
Strength is how much force your muscles can generate against resistance. Stability is how well your body controls that force to keep joints aligned and movements efficient. Both are necessary, but they serve different roles in healthy movement.
In this article, we’ll walk through how physical therapists think about strength versus stability, discuss whether they’re really different, and provide some practical insights on when (and how) you would want to train for one attribute versus the other.
Difference Between Stability and Strength
First, let’s define what exactly we mean by these terms:
What it means to build “strength”
Building strength means increasing a muscle’s ability to produce force against resistance, such as lifting, pushing, or pulling weight. This is typically measured by how much load you can move or how much force you can generate.
A practical example that everyone understands would be thinking about maximal lifts in a gym environment: if our actual (or theoretical) “one rep max” goes up, we can say that we got stronger.
What is means to build (or improve) “stability
Improving stability means enhancing your ability to control movement and maintain proper joint alignment during activity. This relies heavily on coordination, timing, and the nervous system’s ability to regulate motion, not just muscle size or power. Stability exercises can sometimes feel like not much is happening, as we’re working our neurological connection with stabilizer muscles and focusing on functional movement.
A practical example of stability would be the ability to keep a knee aligned over our feet while standing on one leg, slowly bending and straightening the knee.
Can you truly have one without the other?
Yes, to a point—you can develop strength without adequate stability, and this often shows up as poor movement quality or joint pain. In fact, developing the physical skill of being strong without some requisite stability work is a common culprit in injury.
Likewise, you can improve stability without significantly increasing strength, especially early in rehab or training. However, long-term healthy movement and performance require both, working together. Stability allows strength to be expressed safely and efficiently, often preventing injuries. This is especially true in very mobile joints like shoulder joints.
Why the correct answer is typically “both”
Asking what’s more important (stability vs strength) can often be the wrong question to ask. In practice, developing stability will typically have the side effect of increasing our maximal strength somewhat, and vise versa. On some level, we’re always doing “both,” even if our eventual intention is to improve stability for some practical day-to-day reason.
While your physical therapist may be currently emphasizing building a particular attribute around a joint, the reality is that we’re always doing both on some level.
Joint strength vs joint stability
Here is what us as physical therapists concern ourselves with most often, as we’re typically assessing the strength vs stability of a joint in our initial evaluations. In most circumstances, our role is to diagnose and treat the issues causing pain around a certain joint or set of joints. In some cases it’s obvious (sprained ankle, etc), and in others it isn’t (such as with back or hip pain).
The idea of “joint strength” is somewhat of a misnomer, since a joint itself does not produce force. What we’re really referring to is the strength of the muscles and connective tissues that act on and support the joint. Note that connective tissues take longer than muscles to strengthen, and our programs account for that.
Joint stability, on the other hand, describes how well those muscles and tissues work together to control motion and maintain proper joint positioning during movement. A joint can have strong surrounding muscles but still lack stability, which often shows up as poor movement control, compensations, or pain during activity.
Improving the stability of a joint for maximal function
Improving joint stability starts with training control, not just resistance, often using slower, more deliberate movements and lower loads. Exercises that challenge balance, coordination, and joint positioning help the nervous system learn how to maintain alignment under stress.
This does, in many cases, result in an improvement in strength, and sometimes we’ll use direct strengthening methods to achieve our result. After all, the musculature and connective tissue can’t display stability unless they can exert the requisite force necessary to accomplish that task.
Core stability vs core strength
Here is another common area for physical therapists to deal with. The “core” of our body is in many cases what’s responsible for stability throughout our entire kinetic chain – because it’s essentially linking the limbs together. For example, a baseball pitcher exerts force from the ground, through their torso, and into their arm to develop maximal velocity. Core strength (and therefore stability) play a critical role in many of our daily activities, sport-related or otherwise.
Core strength refers to the ability of the trunk muscles—such as the abdominals, back, and hips—to generate force. This is often trained with movements that involve flexion, extension, or rotation of the spine, like sit-ups, resisted twists, or loaded carries.
Core stability refers to the ability to control spinal and pelvic position during movement of the arms and legs or under external load. Rather than producing large amounts of motion, the goal of core stability is to limit unwanted movement and maintain an efficient, neutral position, stabilizing the spine and allowing force to transfer efficiently.
Discussions around core strength vs core stability are common in our practice because a person can have strong core muscles but still lack core stability, which may show up as excessive spinal movement, poor posture under load, or difficulty transferring force between the upper and lower body.
How to figure out if it’s a stability or strength problem
Here are some practical guidelines for determining whether a patient (likely you in this case!) would benefit more from developing their strength or their stability in a given scenario:
- If a movement feels uncontrolled, shaky, or difficult to coordinate—especially at lighter loads or slower speeds, it often points to a stability limitation. These issues tend to show up as loss of balance, joint collapse, or difficulty maintaining proper alignment.
- If you’re having trouble improving your stability despite your efforts to do so, spending some time improving your strength will often be the thing that tips the scales once you return to stability work.
- Strength limitations show up when movement quality is generally good, but we’re requiring our body to perform our movement patterns under more stress or in more compressed timeframes. In these cases, form stays relatively consistent, but the movement fails as load, speed, or fatigue increases.
In reality, many people experience a combination of both, which is why physical therapists assess not just how much force you can produce, but how well you control it throughout the various movements will will assess you on through your course of treatment.
