Purpose: Low back pain is one of the most common musculoskeletal disorders, and lifting is one of its risk factors. The activities of lumbar muscles as the main muscles involved in lifting are important with regard to identification of the allowable limits and the injury mechanisms as well as the motor control aspects. This study aimed to investigate the effects of the lifting speed on the lumbar muscles activities during the lifting of the light loads by squat method.
Methods: In this study, 27 healthy men were tested using electromyography (EMG). The data were collected from the erector spinae and the multifidus muscles. The signal processing was performed using MATLAB software after normalization to MVC and the statistical analysis was performed with SPSS 16. 
Results: The muscles activities at fast, medium, and slow speeds were not significantly different (P>0.05); however, the difference between the numerical values of muscles activities at low and high speeds were clearly visible in the diagram. The highest activity was observed in multifidus muscles and then in erector spinae muscles. 
Conclusion: The results indicated that the lifting speed does not have significant effect on the activity of lumbar muscles during the lifting of light loads, but it should be noted that it can be a risk factor in the long term for individuals who are lifting a lot of loads in a day.