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. Author manuscript; available in PMC: 2018 Dec 7.
Published in final edited form as: Hum Mov Sci. 2017 May 9;54:154–171. doi: 10.1016/j.humov.2017.04.005

Table 2:

Sensitivity of Ankle energy return and Center of Mass work to component stiffness and speed.

Ankle and Center of Mass Work - Dimensionless Redimensionalized Increment Effects
Quantity Mean ± SD
(NS 1.1)		 Slope vs. KFore
P-val 		Coef. KFore*v
P 		Slope vs. KHind
P 		Coef. KHind*v
P 		Slope* vs. Speed v
P 		Mean ± SD
(NS 1.1)		 Slope vs. KFore
(units) 		Coef. KF*v
(units) 		Slope vs. KHind
(units) 		Coef. KH*v
(units) 		Slope* vs. Speed v
(units) 		FID
+15 N/mm
(units) 		HID
+15 N/mm
(units) 		VID
+0.2 m/s
(units)
Prosth. Side Ankle 1.75E−2±4.5E−3 −6.8E−5 −2.6E−4 1.5E−4 −6.2E−4 3.7E−2 13.7±3.5
(J) 		−6.1E−2
(J per N/mm) 		−7.5E−2
(J per N/mm per m/s) 		0.13
(J per N/mm) 		−0.18
(J per N/mm per m/s) 		9.5
(J per m/s) 		−2.2
(J) 		−1.0
(J) 		0.74
(J)
Total Energy Return (Intersegmental)
0.45 0.32 0.01 <0.001 0.009
Prosth. Side Ankle 4.94E−3±2.3E−3 −1.8E−4 3.0E−4 - - −4.1E−2 3.86±1.79
(J) 		−0.16
(J per N/mm) 		8.8E−2
(J per N/mm per m/s) 		- - −10
(J per m/s) 		−1.0
(J) 		- −1.3
(J)
Push-off Energy Ret. (Intersegmental)
0.01 0.15 - - <0.001
Prosth. Side −8.45E−3±4.2E−3 - - −1.0E−4 3.9E−4 −6.0E−2 −6.60±3.27
(J) 		- - −9.0E−2
(J per N/mm) 		0.11
(J per N/mm per m/s) 		−15
(J per m/s) 		- 0.54
(J) 		−2.0
(J)
Negative COM Work In Collision
- - 0.21 0.08 <0.001
Prosth. Side 1.86E−2±2.7E−3 1.2E−4 −6.6E−4 - - 4.6E−2 14.5±2.1
(J) 		0.11
(J per N/mm) 		−0.19
(J per N/mm per m/s) 		- - 12
(J per m/s) 		−1.5
(J) 		- 0.61
(J)
Positive COM Work In Push-Off
0.18 0.01 - - 0.002
Intact Side −1.64E−2±8.6E−3 2.3E−4 −1.0E−3 - - −7.5E−2 −12.8±6.7
(J) 		0.21
(J per N/mm) 		−0.29
(J per N/mm per m/s) 		- - −19
(J per m/s) 		−1.7
(J) 		- −6.5
(J)
Negative COM Work In Collision
0.26 0.08 - - 0.02
Intact Side 2.01E−2±6.5E−3 - - 1.2E−4 −2.6E−4 8.3E−2 15.7±5.1
(J) 		- - 0.11
(J per N/mm) 		−7.6E−2
(J per N/mm per m/s) 		21
(J per m/s) 		- 0.38
(J) 		3.6
(J)
Positive COM Work In Push-Off
- - 0.21 0.32 <0.001
Total (Both Legs) 5.90E−2±6.1E−3 4.0E−4 −9.2E−4 2.1E−4 −3.9E−4 0.14 46.1±4.8
(J) 		0.36
(J per N/mm) 		−0.27
(J per N/mm per m/s) 		0.19
(J per N/mm) 		−0.11
(J per N/mm per m/s) 		35
(J per m/s) 		0.86
(J) 		0.88
(J) 		5.3
(J)
Positive COM Work (Whole Stride)
0.15 0.23 0.19 0.36 <0.001

P-values and Slopes vs. Speed are estimated conservatively. P-values are the greater of the P-values of the Speed coefficient in mixed linear regressions with KForefoot or KHindfoot. Slope values are the lesser of the two Speed coefficients.

-

Indicates statistical test not performed.

NS 1.1: Result for Nominal Stiffness condition at 1.1 m·s−1.