Effect of Prone Blocking on Step Length, Foot Splay

Jason Scoppa
Nov 3, 2024
3 min read

Updated: Apr 3

A Review of Marshall (AECC Project List, 1996)

In 1996, a research project at the Anglo-European College of Chiropractic (AECC) examined an important functional question:

Does prone pelvic blocking influence step length and foot splay in individuals with a pelvic distortion pattern?

The study — Marshall F. Effect of prone blocking on step length and foot splay in subjects with a pelvic distortion pattern. AECC Project List, 1996 — explored whether a structural pelvic intervention could produce measurable changes in gait.

Prone blocking is a hallmark procedure of Sacro Occipital Technique (SOT), developed by Major Bertrand DeJarnette. It involves placing wedge-shaped blocks under the pelvis to influence sacroiliac mechanics and dural tension patterns (DeJarnette, 1979).

The goal is not simply joint manipulation, but neurological and biomechanical rebalancing.

If effective, such an intervention should translate into measurable functional changes — including walking mechanics.

Two simple yet meaningful gait variables are:

Step length – Distance between successive foot contacts
Foot splay (foot progression angle) – Degree to which the foot turns outward during stance

Alterations in pelvic alignment and sacroiliac function can influence lower extremity biomechanics, potentially affecting stride symmetry and foot positioning (Perry & Burnfield, 2010).

Research has demonstrated that pelvic mechanics contribute to lower-limb kinematics during gait (Levangie, 1999). Therefore, assessing step length and foot splay provides a practical way to evaluate functional impact.

The Significance of Marshall’s Study

Marshall’s 1996 project sought to determine whether prone blocking — applied in subjects with pelvic distortion patterns — produced measurable, short-term changes in:

Stride symmetry
Step length
Foot splay angles

This is clinically meaningful because it shifts the focus from static structural findings to dynamic functional outcomes.

If step length becomes more symmetrical or foot splay normalizes following blocking, this suggests:

Improved neuromuscular coordination
Altered load distribution
Potential reduction in compensatory gait strategies

If no significant change occurs, it may indicate:

Gait is influenced by multiple factors beyond pelvic mechanics
Adaptation requires longer-term intervention
Static correction does not immediately translate to dynamic change

Broader Context in Gait Research

Modern gait science emphasizes that walking is a complex integration of:

Pelvic rotation
Sacroiliac motion
Hip mechanics
Proprioceptive feedback
Central motor control

(Perry & Burnfield, 2010)

Interventions affecting pelvic alignment may influence these systems, but the magnitude and consistency of change require careful measurement.

Marshall’s study represents an early attempt to evaluate SOT-style blocking using observable gait metrics — an important step toward outcome-based evaluation.

Effect of Prone Blocking on Step Length and Foot Splay: Clinical Takeaway

For clinicians utilizing pelvic blocking techniques, this research highlights an important principle:

Structural interventions should ideally be evaluated through functional outcomes.

Step length and foot progression angle are simple, reproducible measures that can help determine whether pelvic corrections meaningfully influence locomotion.

Research like Marshall’s encourages practitioners to move beyond “does it feel better?” toward:

Measurable biomechanical change
Functional reassessment
Objective tracking

References

DeJarnette MB. Sacro Occipital Technique Manual. Nebraska City, NE: DeJarnette Publishing; 1979.

Levangie PK. The association between static pelvic asymmetry and low back pain. Spine (Phila Pa 1976).1999;24(12):1234–1242.

Marshall F. Effect of prone blocking on step length and foot splay in subjects with a pelvic distortion pattern. AECC Project List; 1996. (Unpublished student research project.)

Perry J, Burnfield JM. Gait Analysis: Normal and Pathological Function. 2nd ed. Thorofare, NJ: SLACK Incorporated; 2010.