Table 3.

Motor evoked potentials, mean rectified EMG, and force

	Healthy Control	Cervical SCI	P Values
MEP, %
Index finger abduction
30% MVC	151.0 ± 49.0	93.9 ± 11.8	<0.001
70% MVC	231.3 ± 78.8	96.6 ± 23.0	<0.001
Elbow flexion
30% MVC	117.3 ± 33.4	101.7 ± 15.4	<0.05
70% MVC	177.1 ± 41.6	101.0 ± 11.4	<0.001
EMG, mV
Index finger abduction
30% MVC	0.20 ± 0.07 [1.06 ± 0.43%]	0.09 ± 0.07 [1.05 ± 0.83%]	<0.01 [0.97]
70% MVC	0.38 ± 0.15 [2.22 ± 1.03%]	0.13 ± 0.09 [1.49 ± 1.24%]	<0.001 [0.17]
Elbow flexion
30% MVC	0.08 ± 0.07	0.12 ± 0.15	0.51
70% MVC	0.23 ± 0.17	0.32 ± 0.29	0.57
Force, N
Index finger abduction
30% MVC	4.88 ± 1.00 [25.71 ± 5.15%]	2.02 ± 1.69 [23.13 ± 15.37%]	<0.001 [0.62]
70% MVC	11.02 ± 1.60 [58.47 ± 11.74%]	4.69 ± 4.00 [54.56 ± 37.34%]	<0.001 [0.76]
Elbow flexion
30% MVC	30.17 ± 7.48	29.94 ± 13.12	0.96
70% MVC	66.12 ± 14.85	61.09 ± 27.48	0.61

Values are mean ± SD FDI MEP size, mean rectified EMG activity, and force; values in brackets are expressed as % of resting FDI maximal motor response (M-max). FDI MEP size is reported in the resting arm, while mean rectified EMG activity and force are reported in the arm performing 30% and 70% of MVC during index finger abduction and elbow flexion in patients and healthy control subjects. MEP size is expressed as % of baseline MEP size. Note that resting FDI MEP size increased in healthy control subjects but not after cervical SCI. Also note that EMG and force were significantly lower in patients during index finger abduction compared with control subjects and that when EMG activity and force were expressed as % of the FDI M-max (bracketed values) there was no difference across groups. Both groups generated similar EMG and force during elbow flexion. P values represent independent t-tests performed on MEP size, EMG, and force during increasing levels of contraction.