The Trunk’s Role in Sit-to-Stand for Stroke Rehabilitation: A Research Review
Stroke remains one of the most severe neurological diseases worldwide, causing significant disability.
Rehabilitation for stroke survivors (people with stroke, or PWS) focuses on minimizing disability and restoring function at home, in the community, and at work. Hemiparesis, the most common neurological deficit after a stroke, results in muscle weakness or paralysis on one side of the body.
Stroke survivors use different strategies to perform STS due to their asymmetrical deficits.
Importance of Sit-to-Stand (STS)
Sit-to-stand (STS) is one of the most frequent functional activities in daily life. It’s a demanding task, requiring the transfer of the body’s center of mass (COM) against gravity, from a broad base of support (BOS) to a smaller one.
STS is crucial for other daily movements, such as transfers, standing, and walking. However, post-stroke, many individuals struggle with performing this task independently due to various impairments, including weakened trunk muscles.
The Role of the Trunk in Movement:
The trunk plays a key role in maintaining balance and stability. Positioned between the shoulder and pelvic girdles, it serves as a stabilizing anchor for the limbs and helps the body stay upright. The trunk’s ability to shift body weight is crucial for maintaining dynamic postural adjustments during everyday activities.
In stroke survivors, trunk muscles are often weakened on both sides of the body. Even mild weakness can disrupt balance, stability, and the ability to perform functional tasks like STS. Selective movement between the upper and lower trunk is particularly important for functional movements. Post-stroke, it is observed that the lower trunk’s rotation becomes more challenging, making weight shifting toward the affected side more difficult. This leads to further complications in performing independent STS movements.
Phases of Sit-to-Stand:
In the general population, the STS movement is broken down into four phases:
- Phase 1 (P1): The initiation phase, characterized by flexion momentum before the thighs leave the chair. Here, anterior displacement of the center of pressure (COP) occurs with forward trunk movement.
- Phase 2 (P2): The seat-off phase, marked by anterior and vertical displacement of the COM.
- Phase 3 (P3): The extension phase, where the body rises to an erect position.
- Phase 4 (P4): The stabilization phase, where postural control is maintained after the dynamic movement.
How Stroke Affects Sit-to-Stand:
Stroke survivors use different strategies to perform STS due to their asymmetrical deficits. Many sit with a posterior pelvic tilt to compensate for abdominal weakness. However, this limits trunk mobility, making it difficult to initiate the movement required for STS.
During the first phase, stroke survivors may perform forward flexion rather than an anterior weight shift. This causes the trunk and COM to shift toward the unaffected side, a pattern seen throughout the seat-off movement in phase two. The pelvis may also translate toward the unaffected side due to reduced weight-bearing ability in the affected limb.
The extension and stabilization phases (P3 and P4) often merge for stroke survivors, where achieving postural control in standing requires additional effort, as the COM is often shifted toward the unaffected side.
Rehabilitation after a stroke requires a multifaceted approach, especially for complex functional activities like sit-to-stand.
Role of Physiotherapy in Stroke Rehabilitation:
Physiotherapy can play a significant role in helping stroke survivors overcome STS difficulties. Some key interventions include:
- Correcting Pelvic Positioning: Moving the pelvis from a posterior to an anterior pelvic tilt helps improve anterior weight shift, making the seat-off process smoother.
- Foot Placement: Positioning the unaffected leg in front and the affected leg behind forces the person to engage the weaker leg more during STS.
- Strengthening Movements: Using a chair in front for support helps retrain hip extension, while removing the hands from the chair strengthens the abdominal and back stabilizers, assisting with standing upright.
Conclusion:
Rehabilitation after a stroke requires a multifaceted approach, especially for complex functional activities like sit-to-stand.
Targeted physiotherapy can assist stroke survivors in regaining the strength and coordination needed to perform this essential movement more independently.
Reference: Sun.ac.za Research Study
For More Help:
For more information and help, please contact Hesti at the Paarl Branch.
Hesti
Physiotherapist & Practice Owner
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