Differences in lumbopelvic rhythm between trunk flexion and extension.

Area of Science:

• Biomechanics
• Kinesiology
• Movement Science

Background:

• Trunk flexion and extension exhibit distinct characteristics, notably in lumbopelvic rhythm.
• Abnormal lumbopelvic coordination patterns are linked to an increased risk of low back pain.
• Advanced quantification methods like continuous relative phase and phase variability have not been applied to compare trunk flexion and extension rhythms.

Purpose of the Study:

• To investigate the differences in lumbopelvic rhythm between trunk flexion and extension motions.
• To analyze how lumbopelvic rhythm changes within each motion (flexion and extension).

Main Methods:

• Thirteen subjects performed controlled trunk flexion/extension in the sagittal plane.
• Lumbar and pelvic kinematics data were recorded.
• Lumbopelvic continuous relative phase and phase variability were calculated to quantify lumbopelvic rhythm.

Main Results:

• Trunk extension demonstrated significantly lower lumbopelvic continuous relative phase and phase variability compared to flexion, indicating a more in-phase and stable rhythm.
• During trunk extension, the lumbopelvic rhythm shifted from in-phase/stable to out-of-phase/unstable.
• Conversely, trunk flexion showed a progression from out-of-phase/unstable to in-phase/stable lumbopelvic rhythm.

Conclusions:

• The study provides crucial insights into the distinct lumbopelvic rhythm patterns during trunk flexion and extension.
• Quantifying these patterns enables the identification of abnormal coordination in clinical settings.
• These findings can establish normative benchmarks for low back pain rehabilitation programs.