Date of Award


Degree Type


Degree Name

Physical Therapy (M.S.)


Physical Therapy


BACKGROUND A high incidence of back pain is associated with carrying loads asymmetrically and is believed to be influenced by the amount of weight involved and the distance carried. PURPOSE (1) To study the effects of asymmetrical loading on lumbar paraspinal muscle activity. (2) To document ratings perceived exertion (RPE) for carrying an asymmetrical load. METHODS Electromyography (EMG) readings were obtained at the L2/L3 paraspinal level of 12 males and 12 females. All subjects completed three randomized 9-minute trials consisting of walking on a treadmill while carrying an asymmetrical load of either 0, 10 or 20% of their body weight. RESULTS Multifactorial ANOVA revealed that weight was a significant factor in influencing EMG activity on the ipsilateral side but not on the contralateral side (p=0.002 & p=0.085, respectively). Time was not a significant factor on EMG activity on either side. High correlations were found between overall RPE and low back RPE (r=0.859) as well as between the carried load and both overall and lowback RPE (r=0.665 and r=0.652, respectively). A low correlation was found between time and both overall RPE and low back RPE (r=0.351 and r=0.309, respectively). CONCLUSIONS Recommendations for load carriage should place more emphasis on the amount of weight carried rather than duration.


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