Table 4.

Ridge regression of variables affecting half flexion relaxation ratio (HFR)

Coefficients	Estimate	Scaled Est.	SEa	t-value	p-value
Demographics
Gender	-0.106	-0.715	0.803	0.890	0.374
Age	-0.133	-1.410	0.892	1.580	0.114
BMI	-0.023	-1.318	0.833	1.583	0.113
AEQ
APAS-se	-0.019	-0.295	0.904	0.326	0.744
APAS-sl	-0.067	-0.980	0.889	1.102	0.270
PDI	0.003	0.456	0.851	0.536	0.592
RMQ	-0.010	-0.546	0.901	0.606	0.545
IPAQ	-0.001	-1.075	0.776	1.385	0.166
Normalized RMS sEMG amplitude
standing/80 % MVC	-0.004	-1.941	0.850	2.283	0.022	*
Relative RMS SEMG amplitude changes between isometric positions (in percent):
standing – half flexion	0.001	0.559	0.476	1.174	0.240
standing - max flexion	-0.009	-4.625	0.629	7.349	<0.001	*
half - max flexion	-0.009	-4.870	0.597	8.160	<0.001	*
Changes in position angles (in degrees):
lumbothoracic region (standing – maximum flexion)	0.012	1.774	0.587	3.021	0.002	*
lumbothoracic region (standing – half flexion)	-0.006	-0.911	0.577	1.578	0.114
hip region (standing – maximum flexion)	-0.004	-0.702	0.511	1.374	0.170
hip region (standing – half flexion)	-0.007	-0.547	0.764	0.716	0.474
gross trunk region (standing – maximum flexion)	0.004	0.778	0.512	1.520	0.129
gross trunk region (standing – half flexion)	-0.008	-1.181	0.506	2.335	0.020	*
% lumbothoracic of gross trunk region (half flexion)	0.005	0.628	0.639	0.983	0.326
% lumbothoracic of gross trunk region (maximum flexion)	0.004	0.723	0.893	0.810	0.418

^a SE Standard Error (scaled), ridge parameter = 0.1211883 degrees of freedom: model = 14.19 variance = 12.25 residual = 16.14