Table 1.

COP sway parameters (mean ± SD) for firm and compliant surface balance trials with different mechanical noise bandwidths introduced.

Balance surface	Units	Parameter	Vibration bandwidth			P-values
			Control (C)	Wide (W)	Narrow (N)	C versus W	C versus N	N versus W
Firm	mm	ML range	$7.1\pm 1.9$	$7.2\pm 1.8$	$7.0\pm 2.5$	0.854	0.938	0.792
		AP range	$12.4\pm 2.1$	$11.8\pm 2.8$	$11.6\pm 2.3$	0.428	0.382	0.823
	mm/s	ML speed	$2.3\pm 0.6$	$2.5\pm 0.8$	$2.4\pm 0.8$	0.041	0.339	0.074
		AP speed	$3.6\pm 0.4$	$3.7\pm 0.7$	$3.6\pm 0.6$	0.656	0.967	0.608
	mm${}^2$	Swept area	$63.9\pm 27.5$	$62.7\pm 22.3$	$58.3\pm 25.1$	0.901	0.608	0.495
Compliant (foam)	mm	ML range	$17.0\pm 5.0$	$15.2\pm 4.2$	$16.2\pm 4.3$	0.003	0.193	0.095
		AP range	$23.2\pm 5.1$	$21.4\pm 5.4$	$22.8\pm 4.3$	0.201	0.610	0.184
	mm/s	ML speed	$5.1\pm 1.2$	$4.9\pm 1.0$	$5.0\pm 1.3$	0.045	0.099	0.384
		AP speed	$6.2\pm 1.0$	$5.8\pm 0.9$	$6.2\pm 1.2$	0.009	0.399	0.036
	mm${}^2$	Swept area	$298.3\pm 129.7$	$248.1\pm 121.6$	$285.8\pm 124.1$	0.046	0.497	0.009