McCaw et al (1) compared IEMG activity of muscles involved in a free weight bench press versus a Universal machine bench press. 5 trained subjects were tested during trials at 60% 1 RM and 80% 1 RM. Muscle activity of the triceps brachii, anterior deltoid, pectoralis major, biceps brachii, and medial deltoid was measured. FINDINGS: The free weight bench press resulted in higher IEMG values for the anterior and medial deltoid muscles. Group mean data showed a trend towards greater IEMG activity in the pectoralis major for a free weight bench press, but this was not significant and there was a large amount of variability between subjects in this measure. Differences between modes tended to be larger for the 60% 1 RM trials as compared to the 80% 1 RM trials. IMPLICATIONS: A free weight bench press involves greater muscle activity in the deltoids than a machine bench press. Muscle activity of the pectoralis major can vary from individual to individual when comparing a free weight bench press to a machine bench press; some individuals may show greater pectoral activity with a machine while some may show greater activity with free weights.
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