Table 2.

Balance comparisons between controls and HD participants on the single task CTSIB‐M i‐SWAY conditions and narrowed stance condition

CTSIB‐M
Condition 1: Feet apart–eyes open–firm surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.01 ± 0.009	0.31 ± 0.28 ***
Total jerk (m2/s5)	0.56 ± 0.36	19.78 ± 20.33 ***
RMS sway (m/s2)	0.06 ± 0.02	0.19 ± 0.08 ***

Condition 2: Feet apart–eyes closed–firm surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.02 ± 0.01	0.31 ± 0.30 ***
Total jerk (m2/s5)	1.42 ± 1.55	20.69 ± 30.25 ***
RMS sway (m/s2)	0.07 ± 0.02	0.19 ± 0.10 ***

Condition 3: Feet apart–eyes open–foam surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.05 ± 0.04	0.62 ± 0.42 ***
Total jerk (m2/s5)	1.43 ± 1.30	31.60 ± 25.81 ***
RMS sway (m/s2)	0.08 ± 0.03	0.26 ± 0.09 ***

Condition 4: Feet apart–eyes closed–foam surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.12 ± 0.06	1.05 ± 0.93 ***
Total jerk (m2/s5)	4.26 ± 3.16	56.15 ± 45.65 ***
RMS sway (m/s2)	0.13 ± 0.03	0.34 ± 0.12 ***

Narrowed base of support
Feet together–eyes open–firm surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.06 ± 0.02	0.48 ± 0.42 ***
Total jerk (m2/s5)	1.38 ± 0.77	20.55 ± 13.77 ***
RMS sway (m/s2)	0.08 ± 0.01	0.24 ± 0.11 ***

Feet together–eyes closed–firm surface
Variable	Controls	HD
95% Ellipse sway area (m2/s4)	0.10 ± 0.06	0.91 ± 0.78 ***
Total jerk (m2/s5)	3.16 ± 3.16	45.10 ± 40.62 ***
RMS sway (m/s2)	0.10 ± 0.03	0.30 ± 0.14 ***

Data reported as mean ± SD. 95% Ellipse sway area refers to the area of an ellipse covering 95% of the points in both the coronal and sagittal planes, putting more weight on regions more frequently visited. Root mean square (RMS) is the extent of postural sway calculated as RMS of the sway angle in both the AP and ML directions. Total jerk is method to quantify the amount of active postural corrections. Significant differences are bolded.

^* P < 0.05;

^** P < 0.01;

^*** P < 0.001;

^*** P < 0.0001.