Clinical Pilates in Practice: Unstable Sitting & Lumbar Stability

This study compared various measures of lumbar trunk stability with a previously described unstable sitting task1.

Larivière, Christian, Richard Preuss, Daniel Ludvig, and Sharon M. Henry. "Is postural control during unstable sitting a proxy measure for determinants associated with lumbar stability?" Journal of Biomechanics 102 (2020), 109581. doi:10.1016/j.jbiomech.2019.109581.

Of these measures, parameters of lumbar structural function and muscle activation and coordination were predictive for the unstable sitting task2:

• Angular kinematics of pelvis or lumbar spine following rapid arm movement.

• Lumbar intrinsic stiffness when resisting trunk perturbations.

• Thickness of perimuscular connective tissue around abdominal muscles.

• Onset of internal oblique/transverse abdominals and iliocostalis lumborum before rapid flexion/extension of a single arm.

• Percent thickness change of internal oblique and transverse abdominal muscles at rest and contraction.

Key Points: Unstable Sitting & Lumbar Stability

The quality and quantity of movement when sitting on a wobble chair corresponds to measures of lumbar structural function, as well as muscle activation and coordination.

• While not predictive enough to supersede all measures in a research setting, unstable sitting can be used clinically as a tool to assess lumbar stability.

Clinical Pilates in practice

• Integrate unstable sitting into movement assessment, especially for patients with lumbopelvic pathologies.

  → Wunda Chair Seated Leg Press / footwork series.

  → Reformer Leg Press seated on the foot bar.

• Unstable sitting can be replicated in many ways in the Pilates studio.

  → Sit on a core disc/wobble cushion during seated work.

  → Arm Spring Series seated on a stability ball at the end of the Cadillac/Tower.

  → Side Arm Series seated on the Cadillac or Reformer; hang legs to decrease stability.

• Practice limb movements of various amplitude and speed.

References

1.  Shahvarpour, A., Gagnon, D., Preuss, R., Henry, S. and Larivière, C. (2018). Trunk postural balance and low back pain: Reliability and relationship with clinical changes following a lumbar stabilization exercise program. Gait & Posture, 61, pp.375-381.

2. Larivière, C., Preuss, R., Ludvig, D. and Henry, S. (2019). Is postural control during unstable sitting a proxy measure for determinants associated with lumbar stability?. Journal of Biomechanics, p.109581.