The dual task effect on gait in adults with intellectual disabilities: is it predictive for falls?

Figures & data

Table 1. Characteristics of the study sample.

	Total study sample (N = 31)
Personal characteristics
Age
Years, m ± sd, range	42.77 ± 16.70, 20–68
Sex
Female, n (%)	7 (22.6%)
Male, n (%)	24 (77.4%)
Level of ID
Mild, n (%)	15 (48.4%)
Moderate, n (%)	16 (51.6%)
BMI
kg/m^2, m ± sd	27.24 ± 4.51
Normal, n (%)	9 (29.0%)
Overweight, n (%)	15 (48.4%)
Obese, n (%)	7 (22.6%)
Medical information
Genetic syndrome
No genetic syndrome, n (%)	9 (29.0%)
PKU, n (%)	1 (3.2%)
Mosaic mutation, n (%)	1 (3.2%)
Smith–Magenis syndrome, n (%)	1 (3.2%)
Williams syndrome, n (%)	1 (3.2%)
Perlman syndrome, n (%)	1 (3.2%)
No information available on genetic syndrome, n (%)	17 (54.8%)
Spasticity legs
Yes, n (%)	1 (3.2%)
Osteoarthritis
Yes, n (%)	4 (12.9%)
Epilepsy
Yes, n (%)	5 (16.1%)
Visual impairments
Yes, n (%)	4 (12.9%)
Polypharmacy
Yes, n (%)	13 (41.9%)
Physical fitness
Balance one leg
s	7.1 ± 3.83
Balance SPPB
Points out of 4	3.38 ± 0.98
SPPB total
Points out of 12	10.92 ± 1.38
Falls
Fallers (20 complete calendars)
Yes, n (%)	7 (35.0%)
No, n (%)	13 (65.0%)
# of falls, m ± sd, range	1.86 ± 2.27, 1–7

n: number of participants; m: mean; sd: standard deviation; ID: intellectual disability; SPPB: short physical performance battery.

Table 2. Results of the gait parameters while walking at comfortable and while dual tasking, and effect sizes of the comparisons between conditions.

	Comfortable speed condition (n = 31)		Dual task condition (n = 31)		Dual task effect
		m ± sd	95% CI	m ± sd	95% CI	m ± sd			95% CI	Test statistic	d
Spatial parameters
Step length (cm)	65.28 ± 10.14	[61.56, 69.0]	59.13 ± 10.74	[55.19, 63.07]	6.16 ± 4.50	[4.50, 7.81]	7.61^a	0.59** (medium)
Stride length (cm)	130.88 ± 20.25	[123.45, 138.31]	118.49 ± 21.46	[110.62, 126.36]	12.39 ± 9.25	[8.99, 15.78]	7.45^a	0.59** (medium)
Base of support (cm)	11.88 ± 3.51	[10.59, 13.17]	12.58 ± 4.04	[11.09, 14.06]	−0.70 ± 1.75	[−1.34, −0.05]	−2.21^a	−0.18* (small)
Toe in/toe out (degrees)	7.06 ± 7.17	[4.43, 9.69]	7.31 ± 7.64	[4.51, 10.12]	−0.26 ± 2.07	[−1.02, 0.50]	−0.69^a	−0.03 (small)
Temporal parameters
Velocity (cm/s)	118.36 ± 23.43	[109.76, 126.95]	100.21 ± 23.14	[91.72, 108.70]	18.15 ± 13.22	[13.30, 23.0]	7.65^a	0.78** (medium)
Stride velocity (cm/s)	118.98 ± 23.47	[110.37, 127.59]	100.90 ± 22.93	[92.49, 109.32]	18.07 ± 13.42	[13.15, 23.0]	7.50^a	0.78** (medium)
Cadence (steps/min)	108.36 ± 10.19	[104.62, 112.10]	101.02 ± 10.71	[97.09, 104.95]	7.34 ± 6.63	[4.91, 9.77]	6.17^a	0.70** (medium)
Step time (s)	0.56 ± 0.05	[0.54, 0.58]	0.60 ± 0.07	[0.58, 0.62]	−0.04 ± 0.04	[−0.06, −0.03]	−5.75^a	−0.66** (medium)
Stride (cycle) time (s)	1.12 ± 0.11	[1.08, 1.15]	1.20 ± 0.13	[1.15, 1.25]	−0.08 ± 0.08	[−0.11, −0.05]	−5.73^a	−0.66** (medium)
Stance time (s)	0.66 ± 0.08	[0.63, 0.69]	0.71 ± 0.09	[0.68, 0.75]	−0.06 ± 0.05	[−0.07, −0.04]	−6.30^a	−0.59** (medium)
Swing time (s)	0.46 ± 0.04	[0.44, 0.47]	0.49 ± 0.05	[0.47, 0.50]	−0.03 ± 0.03	[−0.04, −0.02]	−4.61^a	−0.66** (medium)
Single support time (s)	0.46 ± 0.04	[0.44, 0.47]	0.49 ± 0.05	[0.47, 0.50]	−0.03 ± 0.03	[−0.04, −0.02]	−4.61^a	−0.66** (medium)
Double support time (s)	0.20 ± 0.06	[0.18, 0.22]	0.23 ± 0.06	[0.21, 0.26]	−0.03 ± 0.03	[−0.04, −0.02]	−5.92^a	−0.50** (medium)
Phasic parameters
Stance, %GC	58.97 ± 1.99	[58.24, 59.70]	59.47 ± 2.02	[58.73, 60.21]	−0.50 ± 0.72	[−0.76, −0.23]	−3.86^a	−0.25** (small)
Swing, %GC	41.03 ± 1.99	[40.30, 41.76]	40.53 ± 2.01	[39.80, 41.27]	0.49 ± 0.73	[0.22, 0.76]	3.76^a	0.25** (small)
Single support, %GC	41.03 ± 1.99	[40.30, 41.76]	40.53 ± 2.01	[39.80, 41.27]	0.50 ± 0.73	[0.23, 0.76]	3.80^a	0.25** (small)
Double support, %GC	18.08 ± 4.08	[16.58, 19.57]	19.31 ± 4.01	[17.84, 20.78]	−1.23 ± 1.81	[−1.89, −0.57]	3.79^a	−0.30** (small)
Variability parameters
Step length SD	2.99 ± 0.89	[2.66, 3.32]	4.14 ± 2.26	[3.31, 4.97]	−1.15 ± 2.37	[−1.88, −0.03]	−2.14^b	−0.67* (medium)
Stride length SD	5.29 ± 1.90	[4.59, 5.99]	7.04 ± 4.08	[5.54, 8.54]	−1.75 ± 4.39	[−3.20, 0.14]	−1.69^b	−0.55 (medium)
Base of support SD	2.51 ± 1.07	[2.12, 2.91]	2.67 ± 1.00	[2.31, 3.04]	−0.16 ± 0.99	[−0.53, 0.12]	−1.16^b	−0.15 (small)
Stride velocity SD	7.07 ± 2.84	[6.03, 8.11]	8.57 ± 4.56	[6.89, 10.24]	−1.50 ± 5.35	[−3.55, 0.78]	−1.25^b	−0.39 (small)
Step time SD	0.02 ± 0.01	[0.02, 0.03]	0.04 ± 0.03	[0.03, 0.05]	−0.01 ± 0.03	[−0.02, −0.003]	−3.07^b	−0.89* (large)
Stride time SD	0.04 ± 0.02	[0.03, 0.04]	0.06 ± 0.05	[0.04, 0.08]	−0.02 ± 0.05	[−0.03, −0.003]	−2.52^b	−0.53* (medium)
Stance time SD	0.03 ± 0.01	[0.026, 0.034]	0.05 ± 0.04	[0.03, 0.06]	−0.02 ± 0.04	[−0.02, −0.003]	−2.81^b	−0.69* (medium)
Swing time SD	0.02 ± 0.01	[0.02, 0.03]	0.03 ± 0.02	[0.02, 0.04]	−0.01 ± 0.01	[−0.01, −0.003]	−3.27^b	−0.63** (medium)
Single support time SD	0.02 ± 0.01	[0.02, 0.03]	0.03 ± 0.02	[0.02, 0.04]	−0.01 ± 0.01	[−0.01, −0.003]	−3.27^b	−0.63** (medium)
Double support time SD	0.03 ± 0.02	[0.02, 0.03]	0.04 ± 0.02	[0.03, 0.04]	−0.01 ± 0.02	[−0.02, −0.002]	−2.47^b	−0.50* (medium)

m: mean; sd: standard deviation; CI: confidence interval; dual task effect: gait parameters comfortable speed condition – dual task condition; % GC: percentage of the gait cycle, d: Cohen’s d as effect size (small (0.2), medium (0.5), large (0.8) effect), a positive effect size means that the mean value in the comfortable speed condition is higher than in the fast or dual task condition.

^at value from paired t test, ^bZ value from Wilcoxon signed-rank test.

*p < 0.05.

**p < 0.002.

Table 3. Correlations between the number of falls experienced and gait during regular walking and the dual task effect.

	r comfortable speed condition – falls	r dual task effect – falls
Spatial parameters
Step length (cm)	0.06, p = 0.801 (small)	−0.23, p = 0.335 (small)
Stride length (cm)	0.08, p = 0.726 (small)	−0.26, p = 0.265 (small)
Base of support (cm)	0.29, p = 0.210 (small)	0.48, p = 0.033* (medium)
Toe in/Toe out (degrees)	0.22, p = 0.351 (small)	0.34, p = 0.141 (medium)
Temporal parameters
Velocity (cm/s)	0.09, p = 0.720 (small)	−0.18, p = 0.456 (small)
Stride velocity (cm/s)	0.09, p = 0.720 (small)	−0.20, p = 0.393 (small)
Cadence (steps/min)	0.05, p = 0.851 (small)	−0.11, p = 0.656 (small)
Step time (s)	0.36, p = 0.121 (medium)	0.15, p = 0.520 (small)
Stride (cycle) time (s)	0.38, p = 0.103 (medium)	0.15, p = 0.520 (small)
Stance time (s)	0.36, p = 0.121 (medium)	0.14, p = 0.550 (small)
Swing time (s)	0.32, p = 0.163 (medium)	0.17, p = 0.474 (small)
Single support time (s)	0.32, p = 0.163 (medium)	0.17, p = 0.474 (small)
Double support time (s)	0.30, p = 0.194 (medium)	0.11, p = 0.651 (small)
Phasic parameters
Stance, %GC	0.36, p = 0.124 (medium)	−0.01, p = 0.952 (small)
Swing, %GC	0.11, p = 0.651 (small)	0.06, p = 0.818 (small)
Single support, %GC	0.11, p = 0.651 (small)	0.08, p = 0.743 (small)
Double support, %GC	0.24, p = 0.316 (small)	0.18, p = 0.441 (small)
Variability parameters
Step length SD	0.46, p = 0.044* (medium)	0.12, p = 0.626 (small)
Stride length SD	0.38, p = 0.099 (medium)	0.14, p = 0.545 (small)
Base of support SD	0.52, p = 0.020* (medium)	−0.05, p = 0.836 (small)
Stride velocity SD	0.35, p = 0.134 (medium)	0.19, p = 0.426 (small)
Step time SD	0.41, p = 0.071 (medium)	0.18, p = 0.441 (small)
Stride time SD	0.40, p = 0.081 (medium)	0.31, p = 0.186 (medium)
Stance time SD	0.41, p = 0.071 (medium)	0.26, p = 0.274 (small)
Swing time SD	0.38, p = 0.101 (medium)	0.27, p = 0.244 (small)
Single support time SD	0.38, p = 0.101 (medium)	0.27, p = 0.244 (small)
Double support time SD	0.26, p = 0.260 (small)	0.09, p = 0.710 (small)

Dual task effect: gait parameters comfortable speed condition – dual task condition; % GC: percentage of the gait cycle; SD: standard deviation; r: Spearman correlation coefficient (small (0.1), medium (0.3), and large (0.5)).

*p < 0.05.

**p < 0.002.