After a stroke, many people notice that their leg does not move exactly the way they want. They may try to lift the foot, but the hip, knee, and ankle all move together. They may try to bend the knee, but the whole leg becomes stiff. They may try to walk, but the foot points down or the knee locks straight.
This can be frustrating, but it is a common part of stroke recovery. In rehabilitation, this type of movement is often called synergy movement. A simple way to understand it is this:
Synergy movement means the leg moves as one connected pattern instead of each joint moving separately.
The hip, knee, ankle, and toes become “linked together.” Instead of choosing one movement, the body produces a whole pattern. Lower-limb synergy patterns after stroke are commonly discussed in relation to flexion and extension synergy, and the Fugl-Meyer lower-extremity assessment includes these types of movements.
What Is In-Synergy Movement?
In-synergy movement means the leg is moving inside a common stroke-related pattern.
In everyday language:
The leg moves like one piece.
One common pattern is a flexion pattern. This may look like the hip bending, the knee bending, and the ankle lifting together. For example, when a person tries to lift the leg, the knee may bend at the same time and the foot may come up as part of the same pattern.
Common examples include:
A person tries to lift the foot, but the whole leg bends together.
A person tries to step forward, but the hip and knee lift too much.
A person tries to move the ankle, but the knee also bends.
A person tries to bring the foot up, but the entire leg comes with it.
Another common pattern is an extension pattern. This may look like the leg becoming stiff and straight. The hip may extend, the knee may lock, and the ankle may point downward. In walking, this can make the leg feel heavy or rigid. Research on lower-limb abnormal synergy after stroke often describes flexor and extensor patterns involving the hip, knee, and ankle together.
Common examples include:
A person tries to stand, but the knee becomes stiff and locks.
A person tries to step, but the foot points downward.
A person tries to walk, but the leg swings forward like a stiff stick.
A person tries to place the foot gently, but the whole leg pushes down strongly.
These patterns are not signs of laziness or lack of effort. They happen because the brain and nervous system are still recovering control after stroke.
What Is Out-of-Synergy Movement?
Out-of-synergy movement means the leg is starting to move outside of those fixed patterns.
In simpler words:
The leg begins to move more freely.
This means the person can control one part of the leg without unwanted movement in another part.
For example:
The person can bend the knee without the hip lifting too much.
The person can lift the ankle without the whole leg bending.
The person can keep the knee soft instead of locked while standing.
The person can place the foot forward with better control.
This kind of movement is very important because walking, standing, turning, climbing stairs, and sitting down all require separate control of the hip, knee, ankle, and foot.
Easy Comparison
In-synergy movement:
The leg moves as a fixed pattern.
Example: When the person tries to lift the foot, the hip and knee also bend.
Out-of-synergy movement:
The person can control joints more separately.
Example: The person lifts the ankle while keeping the knee relatively still.
In-synergy movement:
Unwanted movements come along with the intended movement.
Example: The person tries to step forward, but the whole leg becomes stiff.
Out-of-synergy movement:
The intended movement becomes more isolated.
Example: The person bends the knee without the hip hiking or the foot stiffening.
Why This Matters in Recovery
In stroke rehabilitation, improvement is not only about whether the leg moves. It is also about how the leg moves.
A person may be able to move the leg, but if the leg only moves in a fixed pattern, walking can still be difficult. Recovery becomes more meaningful when the person starts to move outside of synergy patterns.
Therapists often observe questions like:
Can the person bend the knee without the whole leg tightening?
Can the person lift the toes without the hip pulling up?
Can the person stand without the knee locking?
Can the person place the foot gently during walking?
Can the person control the ankle separately from the knee?
These are signs that the nervous system is gaining more selective control. Studies of lower-limb synergy after stroke suggest that abnormal synergy can affect gait, but the ability to generate controlled lower-limb movement is also important for tasks such as standing and walking.
A Simple Takeaway
After stroke, the leg may first move like one connected unit. This is called in-synergy movement. As recovery progresses, the leg may begin to move with more freedom and separation. This is called out-of-synergy movement.
The goal is not just to move more.
The goal is to move with better control.
Even small improvements matter. If the knee locks a little less, if the foot lifts a little more, or if the leg lands more gently during walking, those changes can be meaningful steps toward recovery.