Table 2. Muscle loadings for the first four M-modes in a typical PD patient.

Muscle	Off-drug				On-drug
	M1	M2	M3	M4	M1	M2	M3	M4
TA	0.75	-0.38	-0.17	-0.18	0.73	0.40	-0.25	-0.03
SOL	-0.45	0.72	0.30	0.13	-0.37	-0.86	0.22	-0.03
GM	-0.46	0.77	0.26	0.10	-0.29	-0.91	0.14	-0.01
GL	-0.42	0.74	0.33	0.09	-0.23	-0.86	0.31	-0.01
BF	-0.01	0.90	0.03	-0.03	-0.37	-0.74	0.34	-0.04
ST	0.81	-0.09	-0.01	0.02	-0.17	-0.08	0.76	-0.07
RF	0.86	-0.31	-0.20	-0.06	0.81	0.43	-0.22	0.02
VL	0.78	-0.17	-0.29	0.15	0.82	0.40	-0.15	0.03
VM	0.88	-0.34	-0.09	-0.03	0.88	0.26	-0.14	0.04
TFL	0.87	-0.08	-0.18	0.03	0.85	0.08	-0.25	-0.01
ESL	-0.16	0.16	0.86	0.04	-0.21	-0.35	0.75	0.00
EST	-0.17	0.20	0.85	0.02	-0.23	-0.30	0.73	0.03
RA	0.02	0.08	0.04	0.98	0.02	0.03	-0.04	0.99

Loading factors after Varimax rotation for a typical Parkinson's disease patient in the off-drug and on-drug conditions. Significant loadings (greater than 0.5) are shown in bold. TA - tibialis anterior, SOL - soleus, GM - gastrocnemius medialis, GL - gastrocnemius lateralis, BF - biceps femoris, ST - semitendinosus, RF - rectus femoris, VL - vastus lateralis, VM - vastus medialis, TFL - tensor fasciae latae, ESL - lumbar erector spinae, EST - thoracic erector spinae, RA -rectus abdominis.