Assessing walking adaptability in stroke patients

Figures & data

Figure 1. The set-up of the Interactive Walkway with various walking adaptability tasks (insets).

Table 1. In- and exclusion criteria for stroke patients and controls.

	Stroke	Control
Inclusion criteria	18 years or older Command of the Dutch language Experience residual motor dysfunction (Fugl-Meyer Assessment lower extremity score <34) Able to stand unsupported for more than 20 s and walk independently	18 years or older Command of the Dutch language Unimpaired gait Normal cognitive function (Montreal Cognitive Assessment score ≥23; [13]) Normal or corrected to normal vision
Exclusion criteria	Additional neurological diseases and/or other problems interfering with gait function Less than 12 weeks post-stroke.	Neurological diseases and/or other problems interfering with gait function

Figure 2. Schematics of unconstrained walking and walking adaptability tasks on the Interactive Walkway. The available response distance of the suddenly appearing obstacles and cues varied over subjects depending on their own gait characteristics.

Table 2. Interactive Walkway tasks and outcome measures.

Tasks		# Trials	Level of difficulty	Characteristics	Outcome measure	Unit	Calculation
Unconstrained walking
8-m walking test		2		Walking at self-selected walking speed.	Walking speed	cm/s	The distance travelled between the 0-m and 8-m line on the walkway divided by the time, using the data of the spine shoulder.
					Step length	cm	The median of the differences in the anterior-posterior direction of consecutive step locations.
					Stride length	cm	The median of the differences in anterior-posterior direction of consecutive ipsilateral step locations.
					Step width	cm	The median of the absolute mediolateral difference of consecutive step locations.
					Cadence	steps/min	Calculated from the number of steps in the time interval between the first and last estimate of foot contact.
					Step time	s	The median of the time interval between two consecutive instants of foot contact.
					Stride time	s	The median of the time interval between two consecutive ipsilateral instants of foot contact.
					Symmetry step length	%	Smallest step length (i.e., left or right) divided by the largest step length times 100%.
					Symmetry step time	%	Shortest step time (i.e., left or right) divided by the longest step time times 100%.
Walking adaptability
Obstacle avoidance		5	ART = 1 s (three trials) ART = 0.75 s (two trials)	Avoiding suddenly appearing obstacles.	Obstacle-avoidance margins	cm	The distance of the anterior shoe edge (trailing limb) and posterior shoe edge (leading limb) of the step locations to corresponding obstacle borders during obstacle crossing.
					Success rate	%	Number of successfully avoided obstacles divided by the number of obstacles presented times 100%.
Sudden stops-and-starts		5	ART = 1 s (three trials) ART = 0.75 s (two trials)	Stopping behind the suddenly appearing stop cues and start walking as soon as the cues disappear.	Sudden-stop margins	cm	The minimum distance of the anterior shoe edge to the corresponding stop cue border during the period in which the cue was visible.
					Success rate	%	Number of successful stops divided by the number of stop cues presented times 100%.
					Initiation time	s	The time between disappearance of the stop cue and the moment of first foot contact.
Goal-directed stepping	SSS ISS	3 2	Average SL 75% average SL 125% average SL 25% variation in SL left and right 50% variation in SL left and right	Stepping as accurately as possible onto the shoe-size-matched stepping stones.	Stepping accuracy	cm	The standard deviation over the signed deviations between the center of the stepping target and the center of the foot at corresponding step locations. The center of the foot was determined using the average distance between the ankle and the middle of the shoe-size-matched targets of the calibration trials.
					Normalized walking speed	%	Walking speed divided by walking speed of the 8MWT times 100%.
Narrow walkway		2	WW = 1.5*SW + FW WW = SW + FW	Walking between the lines of the walkway.	Success rate	%	Number of steps inside the walkway divided by the total number of steps taken times 100%.
					Normalized walking speed	%	Walking speed divided by walking speed of the 8MWT times 100%.
					Normalized step width	%	Step width divided by the imposed step width times 100%.
Speed adjustments	SU SD	2 2	120% SSWS 140% SSWS 80% SSWS 60% SSWS	Start walking and when a speed cue appears one meter in front of the subjects it has to be followed at the imposed speed.	Success rate	%	The percentage of the time spend walking faster (or slower) than the imposed speed minus (or plus) 20% during the period in which the speed cue was visible.
					Normalized walking speed	%	Walking speed divided by the imposed walking speed times 100%.
Slalom		2	Symmetric distance between obstacles Variable distance between obstacles	Walking around the moving obstacles that approach the subjects with a speed of 50% SSWS.	Success rate	%	Number of successfully avoided obstacles divided by the number of obstacles presented times 100%.
					Normalized walking speed	%	Walking speed divided by walking speed of the 8MWT times 100%.
Turning	HT	2	ART = 3 s ART = 2 s	Start walking and when a turning cue approaches the subject with a speed of 100% SSWS, the subject has to turn and walk back to the start.	Success rate	%	Number of successful half turns divided by the number of half turns times 100%.
					Turning time	s	Time within the turning square (for full turns) or time from appearance of the turning cue till moment walking direction was reversed (for half turns), using the data of the spine shoulder.
	FT	1		In the two presented squares the subject has to make a full turn as fast and safe as possible in the direction of the arrow.
Dual-task walking	PDT	2		Walking while also performing a dual task. The dual task was an auditory Stroop task.	Normalized walking speed	%	Walking speed divided by walking speed of the 8MWT times 100%.
					Success rate dual task	%	Number of correct responses divided by the number of stimuli given times 100%.
	ADT	5	ART = 1 s (three trials) ART = 0.75 s (two trials)	Avoiding suddenly appearing obstacles while also performing a dual task. The dual task was an auditory Stroop task.	Normalized success rate	%	Obstacle avoidance success rate divided by success rate of the obstacle avoidance task times 100%, excluding subjects that had an obstacle-avoidance success rate of 0% at baseline.
					Success rate dual task	%	Number of correct responses divided by the number of stimuli given times 100%, excluding subjects that had an obstacle-avoidance success rate of 0% at baseline.
Total		35

SSS: symmetric stepping stones; ISS: irregular stepping stones; SU: speeding up; SD: slowing down; HT: half turns; FT: full turns; PDT: plain dual-task walking (8-meter walking test with dual task); ADT: augmented dual-task walking (obstacle avoidance with dual task); ART: available response time; SL: step length; WW: walkway width; SW: step width; FW: foot width; SSWS: self-selected walking speed of unconstrained walking.

Table 3. Means, standard deviations and between-groups statistics of outcome measures of clinical tests, unconstrained walking and walking adaptability tasks on the Interactive Walkway for stroke patients and controls.

			Stroke	Control
			mean ± std	mean ± std	t-value	p-value	r-value
Clinical tests
Timed-Up-and-Go test	Time (s)*		17.3 ± 11.4	7.4 ± 2.2	t31.1 = −4.62	<0.001	0.638
10-m walking test	Time (s)*	CWS	16.6 ± 13.2	7.3 ± 1.0	t29.3 = −3.83	0.001	0.577
	Time (s)*	MWS	13.5 ± 11.3	5.3 ± 0.8	t29.3 = −3.94	<0.001	0.588
Tinetti Balance Assessment	Score*		21.1 ± 5.0	27.7 ± 0.5	t29.6 = 7.19	<0.001	0.797
7-item Berg Balance Scale	Score*		10.0 ± 2.5	13.3 ± 1.3	t43.8 = 6.50	<0.001	0.701
Functional Reach Test	Reaching distance (cm)*		22.3 ± 7.2	29.9 ± 5.6	t58 = 4.60	<0.001	0.517
Unconstrained walking
8-m walking test	Walking speed (cm/s)*		83.0 ± 34.6	134.3 ± 19.0	t45.0 = 7.11	<0.001	0.727
	Step length (cm)*		52.4 ± 14.2	74.5 ± 9.4	t50.3 = 7.10	<0.001	0.707
	Stride length (cm)*		105.3 ± 28.7	149.9 ± 18.7	t49.8 = 7.13	<0.001	0.711
	Step width (cm)*		17.3 ± 5.5	11.1 ± 2.8	t43.3 = −5.55	<0.001	0.645
	Cadence (steps/min)*		94.0 ± 20.5	112.3 ± 7.5	t36.7 = 4.57	<0.001	0.602
	Step time (s)*		0.669 ± 0.184	0.526 ± 0.038	t31.4 = −4.15	<0.001	0.595
	Stride time (s)*		1.335 ± 0.378	1.047 ± 0.074	t31.2 = −4.10	<0.001	0.591
	Symmetry step length (%)*		85.5 ± 15.0	96.6 ± 2.3	t30.3 = 4.03	<0.001	0.591
	Symmetry step time (%)*		78.7 ± 13.8	96.1 ± 2.9	t31.5 = 6.80	<0.001	0.771
Walking adaptability
Obstacle avoidance	Margins trailing limb (cm)*		9.0 ± 8.4	19.9 ± 7.3	t58 = 5.38	<0.001	0.577
	Margins leading limb (cm)*		2.3 ± 6.8	12.1 ± 6.1	t58 = 5.88	<0.001	0.611
	Success rate (%)*		45.1 ± 32.4	88.2 ± 11.3	t35.9 = 6.88	<0.001	0.754
Sudden stops-and-starts	Sudden-stop margins (cm)*		−1.8 ± 7.2	5.4 ± 9.2	t57 = 3.33	0.002	0.403
	Success rate (%)*		56.5 ± 25.9	76.8 ± 18.5	t50.7 = 3.46	0.001	0.437
	Initiation time (s)*		1.653 ± 0.462	1.338 ± 0.235	t41.3 = −3.28	0.002	0.455
Goal-directed stepping	Stepping accuracy (cm)*	SSS	3.7 ± 1.7	2.5 ± 0.7	t35.6 = −3.48	0.001	0.504
	Normalized walking speed (%)*	SSS	78.5 ± 18.9	96.0 ± 16.5	t56 = 3.77	<0.001	0.449
	Stepping accuracy (cm)	ISS	4.8 ± 2.1	3.9 ± 1.0	t40.4 = −1.97	0.056	0.296
	Normalized walking speed (%)*	ISS	77.7 ± 18.4	96.0 ± 15.7	t57 = 4.11	<0.001	0.478
Narrow walkway	Success rate (%)*		68.7 ± 27.4	84.3 ± 17.4	t57 = 2.62	0.011	0.328
	Normalized walking speed (%)*		80.4 ± 17.3	99.0 ± 11.9	t57 = 4.83	<0.001	0.539
	Normalized step width (%)*		66.8 ± 30.2	37.7 ± 16.1	t57 = −4.64	<0.001	0.523
Speed adjustments	Success rate (%)*	SU	58.5 ± 13.9	69.7 ± 10.1	t47.0 = 3.46	0.001	0.450
	Normalized walking speed (%)	SU	87.8 ± 9.9	90.2 ± 6.7	t44.8 = 1.07	0.291	0.158
	Success rate (%)*	SD	72.3 ± 6.8	79.1 ± 5.2	t55 = 4.24	<0.001	0.496
	Normalized walking speed (%)*	SD	102.9 ± 4.1	99.4 ± 2.3	t40.1 = −3.94	<0.001	0.528
Slalom	Success rate (%)*		43.3 ± 21.1	55.3 ± 23.0	t54 = 2.03	0.048	0.266
	Normalized walking speed (%)*		79.8 ± 15.5	94.7 ± 9.6	t40.5 = 4.23	<0.001	0.554
Turning	Success rate (%)*	HT	11.1 ± 25.3	65.0 ± 35.1	t52.6 = 6.69	<0.001	0.678
	Turning time (s)	HT	1.533 ± 0.285	1.435 ± 0.251	t55 = −1.38	0.174	0.182
	Turning time (s)*	FT	6.1 64 ± 4.508	2.149 ± 0.961	t28.1 = −4.53	<0.001	0.650
Dual-task walking	Normalized walking speed (%)*	PDT	79.7 ± 14.2	87.7 ± 9.5	t56 = 2.54	0.014	0.321
	Success rate dual task (%)*	PDT	77.4 ± 21.6	94.9 ± 12.2	t43.9 = 3.80	<0.001	0.498
	Normalized success rate (%)	ADT	80.8 ± 69.3	97.2 ± 23.9	t27.4 = 1.11	0.277	0.208
	Success rate dual task (%)*	ADT	68.3 ± 24.8	91.6 ± 9.2	t28.1 = 4.38	<0.001	0.637

CWS: comfortable walking speed; MWS: maximum walking speed; SSS: symmetric stepping stones; ISS: irregular stepping stones; SU: speeding up; SD: slowing down; HT: half turns; FT: full turns; PDT: plain dual-task walking (8-meter walking test with dual task); ADT: augmented dual-task walking (obstacle avoidance with dual task).

^* Significant between-groups difference (p < 0.05).

Figure 3. Overview of the correlation coefficients between commonly used clinical test scores [TUG, 10MWT-CWS, 10MWT-MWS, TBA, BBS, FRT] (x-axis), spatiotemporal gait parameters of unconstrained walking [UW1-9] (x-axis) and Interactive Walkway walking-adaptability outcome measures (OA1-3, SSS1-3, GDS1-4, NWW1-3, SA1-4, S1-2, T1-3, DT1-4; y-axis) in stroke patients. The order and abbreviations of the outcome measures on the axes is in agreement with Table 3.

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Data availability statement

The data that support the findings of this study are available from the corresponding author, DJG, upon reasonable request.