Effect of angle of traction pull on upper trapezius muscle activity*.
Seven female subjects with no history of cervical trauma were subjected to intermittent cervical traction to determine the effect of angle of traction pull on upper trapezius muscle activity. The EMG of the upper trapezius muscle was recorded when a force of 30 pounds was applied at angles of 7 0 O, 25 O, and 35 O. An intermittent traction cycle of 7-second duration for each phase was used for the contract-relax sequence. Statistical analysis revealed that a positive relationship existed between an increase in angle of pull and muscle activity. J Orthop Sports Phys Ther 1980;1(4):205-209.
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