Electromyography analysis of the free barbell squat: A systematic review

Abstract

Purpose: To conduct a systematic review of studies that evaluate electromyography muscle activation in the free barbell back squat (BS), and the changes produced by the effect of kinetic and kinematic factors. Methods: This study was conducted according to The PRISMA declaration and the STROBE guidelines to assess the methodological quality. Databases included were Scopus, PubMed, Scielo y Cochrane Central Register of Controlled Trials (CENTRAL). A total of 1889 original articles were selected using the inclusion criteria as follows: subjects previously experienced in resistance training including EMG assesment during the execution of the BS. The final selection consisted of 18 articles. Results: The evidence suggest to the quadriceps femoris and vastus medialis as the muscle group and the muscle with the greatest participation in BS. Muscle activity in BS can be affected by load, speed of execution, resistance type, and range of motion. There is a relationship between high muscle activity and increased load or velocity in the lift back up phase, however, increased load tends to negatively affect velocity in squat performance. Conclusions: Submaximal loads seem to produce similar muscle activation to the 1RM, with the incentive of a lower risk of injury compared to the maximum loads. More studies with unified methodological criteria are required to identify the optimal muscle activation based on the load.