Table 3.

PLS regression of group membership using the intramuscular variables as regressors (R ² = 0.31)

Variable	Time point	VIP	Sign of coeff
[BKN]	150 min	1.43	-
Blood flow	150 min	2.57	+
	170 min	2.44	+
	190 min	2.28	+
	210 min	2.35	+
	310 min	1.83	+
	325 min	1.02	+
	335 min	1.87	+
	345 min	1.60	+
	355 min	1.93	+
HHB	Recov1b	1.20	-
OHb	21-40 min	1.44	-
	PEG-0-20 min	1.13	-
	recov2	1.02	-
	STR	1.04	-
[ Lactate ]	150 min	1.02	+
	170 min	1.05	+
	190 min	1.21	+
	210 min	1.20	+
	325 min	1.02	+
	325 min	1.39	+
	335 min	1.02	+
[ Pyruvate ]	150 min	1.33	+
	170 min	1.30	+
	190 min	1.78	+
	210 min	1.14	+
	325 min	1.41	+
[ Glucose ]	310 min	1.15	+
[ Glutamate ]	150 min	1.06	+
	170 min	1.11	-
[ K + ]	150 min	1.11	+
	190 min	1.83	-
	325 min	1.59	+
	345 min	1.30	+
[ IL-6 ]	210 min	1.71	-
	310 min	1.35	-
[LDH]	335 min	1.07	+

[substance] denotes concentration of the substance. BKN = Bradykinin, HHB = deoxy-haemoglobin, OHB = oxyhaemoglobin, K⁺ = potassium, IL-6 = interleukin 6, LDH = Lactate dehydrogenase, PEG = repetitive low-force exercise performed unilaterally on a pegboard, STR = STROOP test.

Trapezius myalgia (TM) was denoted 1 and healthy controls (CON) was denoted 0. VIP values and sign of coefficient (coeff) are given. Note that the variables are grouped and sorted within each variable with respect to the time points. A positive coefficient indicates that TM has high values on this variable compared to CON and vice versa. Note the inverse construction of blood flow.