. Author manuscript; available in PMC: 2017 Aug 1.

Published in final edited form as: J Neurol. 2016 May 18;263(8):1518–1529. doi: 10.1007/s00415-016-8158-4

Table 3.

Retention of improvements, represented as mean (SD), in backward and forward protective stepping performance in people with PD and healthy older adults (HO). Retention was only analyzed if a significant improvement was observed across day 1 practice.

	Grp	Start Train (block 1)	Retention	Group Effect	Time Effect (Retention)	Group x Retention Interaction

*BACKWARD PERTURBATIONS*
*Primary Variable*

^*COM displacement (m)	HO	0.28(0.05)	0.25(0.03)	Z=0.922	*Z=−2.86*	Z=−0.586
^*COM displacement (m)	PD	0.31(0.11)	0.26(0.11)	p=0.943	*p=0.004*	p=0.581

*Secondary Variables*

^*Margin of Stability (m)	HO	0.11(0.08)	0.12(0.04)	Z=−0.878	*Z=−3.12*	Z=−1.03
^*Margin of Stability (m)	PD	0.07(0.04)	0.11(0.04)	p=0.399	*p=0.002*	p=0.323

Step Latency (ms)	HO	293(9)	293(11)	F_1,23=0.238	F_1,23=0.015	F_1,23=0.068
Step Latency (ms)	PD	300(7)	297(10)	p=0.63	p=0.903	p=0.796

Number of Steps	HO	2.03(0.63)	1.60(0.48)	F_1,25=0.46	*F_1,25=28.9*	F_1,25=0.22
Number of Steps	PD	2.17(0.85)	1.81(0.70)	p=0.504	*p<0.001*	p=0.64

*FORWARD PERTURBATIONS*
*Primary Variable*

COM displacement (m)	HO	0.28(0.11)	0.23(0.05)	F_1,25=2.0	F_1,25=6.832	F_1,25=2.591
COM displacement (m)	PD	0.23(0.05)	0.21(0.06)	p=0.167	*p=0.015*	p=0.12

*Secondary Variables*

^*Number of Steps	HO	1.53(0.52)	1.00(0.37)	Z=−0.20	*Z=−3.27*	Z=−1.71
^*Number of Steps	PD	1.52(0.62)	1.30(0.41)	p=0.843	*p=0.001*	p=0.093

Non-parametric statistical assessments used

EMG- Electromyograhy; COM- Center of mass; HO- Healthy older adult; PD- Parkinson’s disease