Table 3.

Results of change in EMG amplitudes as percentage of MVIC.

Healthy Group (n 14); Painful Group (n 11)	Baseline EMG Amplitude	3-week Follow up EMG Amplitude	Interaction for group x time	Post-hoc testing (p-value)
Concentric UT
Healthy Group	43 ± 12	41 ± 13	0.335
Painful Group	55 ± 19	49 ± 16
Eccentric UT
Healthy Group	21 ± 7	20 ± 10	0.086
Painful Group	30 ± 17	23 ± 8
Concentric LT*
Healthy Group	17 ± 8	15 ± 5	0.045*	0.930
Painful Group	28 ± 12	21 ± 7		0.006†
Eccentric LT‡
Healthy Group	9 ± 4	9 ± 4	0.081
Painful Group	18 ± 9‡	13 ± 4‡

^* = Indicates a significant group by time interaction

^† = indicates a significant change between baseline and 3-week follow up

^‡ = indicates a significant main effect of group (p = 0.004). The painful group had significantly greater EMG amplitude at both time points compared to the healthy group.

UT = Upper Trapezius

LT = Lower Trapezius