Parkinson’s disease gradually affects posture by causing a progressive stooping or forward-leaning stance, reduced trunk rotation, and impaired balance that worsen over time. This happens because Parkinson’s disease disrupts the brain’s control over movement, leading to muscle stiffness, slowness, and difficulty maintaining upright posture.
At the start, people with Parkinson’s may notice subtle changes such as a slight forward tilt of the head and shoulders, or a tendency to slouch. This stooped posture is linked to rigidity—muscle stiffness that resists movement—and bradykinesia, which slows the initiation and execution of movements. As these symptoms intensify, the natural ability to stand tall and move fluidly diminishes. The muscles around the spine and trunk become less flexible, and the automatic adjustments that keep balance become impaired.
Over time, the disease affects the coordination between limbs and trunk, disrupting the smooth, rhythmic patterns of walking and posture control. The basal ganglia, a brain region critical for automatic movement regulation, deteriorates, leading to poor timing and synchronization of movements. This results in a shuffling gait, reduced arm swing, and a rigid, inflexible trunk that cannot rotate normally during walking. The loss of trunk rotation further contributes to a hunched posture and makes balance more precarious.
Postural instability, a hallmark of later stages of Parkinson’s, means the body struggles to maintain equilibrium, especially when standing or changing positions. This instability increases the risk of falls and often causes individuals to adopt a wider base of support or lean forward more to compensate. The forward stoop becomes more pronounced, and the person may appear as if they are leaning into their steps to avoid falling backward.
Additionally, Parkinson’s disease can affect the sensory feedback mechanisms that help the brain understand body position in space. Reduced sensitivity in leg muscles and joints impairs the detection of ground forces, making it harder to adjust posture dynamically. This sensory deficit, combined with motor impairments, leads to a rigid, less adaptive posture.
The shrinking of movement amplitude, often described as “movement shrinking,” means that steps become shorter and posture more contracted. Everyday tasks that require reaching, bending, or twisting become more difficult because the body’s natural alignment and flexibility are compromised.
In summary, Parkinson’s disease affects posture through a combination of muscle rigidity, slowed movement, impaired coordination, and sensory deficits. These changes start subtly but progressively worsen, leading to a characteristic stooped, shuffling, and unstable posture that challenges balance and mobility.
