Table 1.

Axial and Lateral Tissue Displacement and Lateral Shear Strain

	Location 1: between muscles		Location 2: over muscle
Ultrasound image zones	Transverse	Longitudinal	Transverse	Longitudinal	Location p-value	Orientation p-value	Interaction p-value
Zone 1
Axial displacement	86.3±25.8	156.9±46.9	151.2±45.2	131.9±39.4	0.325	0.241	0.068
Lateral displacement	183.5±26.7	126.5±18.4	233.1±33.9	100.6±14.6	0.965	<0.0001	0.057
Shear strain	3.2±0.6	3.3±0.6	3.2±0.6	2.2±0.4	0.189	0.294	0.198
Zone 2
Axial displacement	45.6±13.8	142.3±43.2	110.4±33.5	94.3±28.6	0.114	0.002	0.0002
Lateral displacement	182.5±24.0	140.2±18.4	270.3±35.5	119.6±15.7	0.244	<0.0001	0.009
Shear strain	2.7±0.5	3.9±0.8	3.6±0.7	2.3±0.5	0.539	0.85	0.038
Zone 3
Axial displacement	68.8±23.7	213.8±74.8	130.2±44.9	131.1±45.3	0.669	0.003	0.003
Lateral displacement	195.9±30.7	214.4±33.6	303.2±47.4	170.1±26.6	0.041	0.059	0.012
Shear strain	3.3±0.6	5.4±0.9	4.4±0.7	4.2±0.7	0.809	0.209	0.125
Zone 4
Axial displacement	244.7±74.6	1051.5±320.3	361.1±110.0	526.4±160.4	0.489	0.0003	0.019
Lateral displacement	251.7±48.4	515.4±99.2	441.4±84.9	372.8±71.7	0.456	0.094	0.009

Axial and lateral tissue displacement values represent cumulative displacement (μm) over 1 complete needle oscillation (up and down). Shear strain (%) represents the percent shear deformation between layers within perimuscular connective tissue. Displacement and strain values are expressed as mean±standard error. The p-values represent differences between location (between muscles vs. over muscles), orientation (transverse vs. longitudinal), and the interaction of the 2 conditions. Note: lateral shear strain was not calculated for Zone 4 due to the relatively large axial motion in the zone closest to the needle.