Mechanosensitivity of the lower extremity nervous system during straight-leg raise neurodynamic testing in healthy individuals.
METHODS
Cross-sectional, observational study.


OBJECTIVE
To explore how ankle position affects lower extremity neurodynamic testing.


BACKGROUND
Upper extremity limb movements that increase neural loading create a protective muscle action of the upper trapezius, resulting in shoulder girdle elevation during neurodynamic testing. A similar mechanism has been suggested in the lower extremities.


METHODS
Twenty healthy subjects without low back pain participated in this study. Hip flexion angle and surface electromyographic measures were taken and compared at the onset of symptoms (P1) and at the point of maximally tolerated symptoms (P2) during straight-leg raise tests performed with ankle dorsiflexion (DF-SLR) and plantar flexion (PF-SLR).


RESULTS
Hip flexion was reduced during DF-SLR by a mean +/- SD of 5.5 degrees +/- 6.6 degrees at P1 (P = .001) and 10.1 degrees +/- 9.7 degrees at P2 (P<.001), compared to PF-SLR. DF-SLR induced distal muscle activation and broader proximal muscle contractions at P1 compared to PF-SLR.


CONCLUSIONS
These findings support the hypothesis that addition of ankle dorsiflexion during straight-leg raise testing induces earlier distal muscle activation and reduces hip flexion motion. The straight-leg test, performed to the onset of symptoms (P1) and with sensitizing maneuvers, allows for identification of meaningful differences in test outcomes and is an appropriate end point for lower extremity neurodynamic testing.
Boyd
Benjamin S
BS
Samuel Merritt University, Department of Physical Therapy, Oakland, CA 94609, USA. bboyd1@samuelmerritt.edu
Wanek
Linda
L
Gray
Andrew T
AT
Topp
Kimberly S
KS
D000328:Adult; D000843:Ankle Joint / Q000294:innervation / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000294:innervation / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000294:innervation / Q000502:physiology; D007866:Leg / Q000294:innervation*; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D012016:Reference Values; D012584:Sciatic Nerve / Q000502:physiology*