Table 9.

OPLS regressions of blood flow at baseline (140 min) in erector spinae in all subjects taken together, in CON, and in FM. Regressors used data from spectroscopy and MD data from baseline of this muscle (except pain variables from microdialysis). Only significant variables are shown (i.e., variables with VIP > 1.0 and absolute p(corr) ≥0.50).

All			CON			FM
Variables	VIP	p(corr)	Variables	VIP	p(corr)	Variables	VIP	p(corr)
ATP	1.63	0.71	Pi/PCr	1.53	−0.68	Pi/PCr	1.87	−0.86
Pi/PCr	1.62	−0.71	ATP	1.42	0.64	Pi/Ptot	1.69	−0.78
Pi/Ptot	1.45	−0.64	Glycerol Erector spinae 140 min	1.39	−0.63	PCr/Ptot	1.68	0.78
PCR	1.43	0.62	Pi/Ptot	1.37	−0.61	PCR	1.17	0.54
PCr/Ptot	1.42	0.62	PCr/Ptot	1.20	0.54	ATP	1.14	0.52
R2	0.50		R2	0.56		R2	0.37
Q2	0.45		Q2	0.47		Q2	0.25
CV-ANOVA p-value	< 0.001		CV-ANOVA P-value	<0.001		CV-ANOVA P-value	0.022
n	55		n	25		n	30

VIP and p(corr) are reported for each regressor (i.e., the loading of each variable scaled as a correlation coefficient and therefore standardizing the range from −1 to + 1). The sign of p(corr) indicates the direction of the correlation with the dependent variable (+ = positive correlation; − = negative correlation). Hence, a positive p(corr) for a certain variable indicates a positive correlation with blood flow of erector spinae in the multivariate context. The four bottom rows of each regression report R², Q², P -value of the CV-ANOVA, and number of subjects included in the regression (n) from the OPLS regression (see Statistics for details).