Prediction of trapezius muscle activity and shoulder, head, neck, and torso postures during computer use: results of a field study

Table 4 Predictions of range of amplitude of trapezius muscle activity and range of motion shoulder, head, neck, and torso postures

Range of Amplitude/Range of Motion	Task-based predictions			Expanded model predictions¹
Range of Amplitude/Range of Motion	R²	RMS	Relative RMS	R²	RMS	Relative RMS
Shoulder EMG (%MVC)
Right Trapezius	0.00	4	18	0.40	3	10
Left Trapezius	0.00	4	16	0.43	4	13
Shoulder Posture (degrees)
Right Abduction	0.02	9	16	0.36	8	13
Left Abduction	0.02	8	17	0.35	7	15
Right Flexion	0.02	8	16	0.39	7	14
Left Flexion	0.01	10	19	0.41	8	16
Right Internal Rotation	0.00	21	30	0.22	14	20
Left Internal Rotation	0.04	15	23	0.36	14	21
Head Posture (degrees)
Tilt	0.00	10	14	0.41	7	9
Flexion	0.03	22	35	0.39	9	14
Neck Posture (degrees)
Tilt	0.01	3	16	0.33	3	14
Flexion	0.05	7	16	0.42	6	13
Torso Posture (degrees)
Tilt	0.01	16	42	0.34	4	10
Flexion	0.02	11	29	0.30	8	20

¹R², RMS, and Relative RMS are the average values from jackknifed calculations.
Comparison of task-based and expanded model predictions based on R² values, RMS errors, relative RMS errors.

ISSN: 1471-2474