Using continuous relative phase and modified vector coding analyses to quantify spinal coordination and coordinative...

Area of Science:

• Biomechanics
• Motor Control
• Clinical Biomechanics

Background:

• Movement coordination and variability differ in individuals with low back pain.
• Quantification methods for these metrics vary, leading to uncertainty in preferred analytical approaches.

Purpose of the Study:

• To compare coordination and coordinative variability between individuals with and without low back pain during a lifting task.
• To determine which analytical technique, continuous relative phase or vector coding, is more effective at detecting group differences.

Main Methods:

• Electromagnetic motion capture was used to record kinematic data of the upper lumbar, lower lumbar, and hip joints in 47 adults with low back pain and 17 without.
• Coordination and coordinative variability were quantified using continuous relative phase (mean absolute relative phase, deviation phase) and vector coding (coupling angle, coupling angle variability).
• Statistical analyses included T-tests and Cohen's d bootstrapping to compare groups and assess technique sensitivity.

Main Results:

• The low back pain group demonstrated less in-phase movement and greater variability across joint pairs, irrespective of the analytical technique used.
• Qualitative analysis indicated reduced motion at the lower lumbar spine in the low back pain group during lifting and lowering.
• Continuous relative phase analysis was more sensitive to differences in coordinative variability, whereas vector coding was more sensitive to differences in coordination.

Conclusions:

• Both continuous relative phase and vector coding provide distinct information regarding movement coordination and variability in low back pain.
• The choice of analytical technique should align with specific research objectives to effectively identify group differences.