Comparison Of 1RM Strength And Muscle Activation Between The Smith Machine And Free Weight Bench Press In Experienced And Inexperienced Lifters

Abstract

PURPOSE: The purpose of this study was to compare 1RM strength and muscle activation of the anterior deltoid, medial deltoid, and pectoralis major during the Smith machine and free weight bench presses in experienced and inexperienced lifters. METHODS: Fourteen experienced (age, 19.9 ± 2.1 years; height, 176.3 ± 7.5 cm; mass, 88.5 ± 19.4 kg) and twelve inexperienced (age, 20.5 ± 2.1 years; height, 179.8 ± 8.0 cm; mass, 75.5 ± 10.4 kg) men completed two testing sessions. The first testing session consisted of determining each subject's 1RM on either the Smith Machine or free weight bench press. Surface EMG electrodes were placed superficial to the anterior deltoid, medial deltoid and pectoralis major muscles prior to 1RM testing to measure muscle activation. One week later, subjects completed the same 1RM testing protocol for the mode not tested during the first session. RESULTS: Both experienced and inexperienced lifters had a significantly higher (p<0.05) 1RM on the free weight bench press, but experienced lifters had a larger difference in 1RMs between the two modes. Activation of the medial deltoid was significantly higher (p<0.05) on the free weight bench press compared to the Smith machine bench press, regardless of experience level. There was no difference in the activation of the anterior deltoid or pectoralis major between modes. CONCLUSION: The results suggest that the instability caused by the free weight bench press necessitates a greater response by the medial deltoid as a stabilizer of the humerus in the glenohumeral joint. Also, the free weight bench press might allow for a greater expression of strength due to its reverse "C" bar path which may be more familiar and natural to experienced and inexperienced bench pressers than the linear bar path offered by the Smith machine.