Q+A: Does a free-weight exercise activate muscles differently than a machine exercise?


by Matt Brzycki

In one study, 12 subjects (average age 21.8) were randomly assigned to perform three exercises—bench press, shoulder (overhead) press and close-grip bench press—with a barbell and, separately, with a Smith machine. During each exercise session, the researchers collected electromyographic (EMG) data for the pectoralis major, anterior deltoid, triceps and biceps.

The study found that doing the three exercises with a barbell using a 10-repetition maximum load produced no significant differences in muscle activity compared with doing the same routine on a Smith machine. In other words, the involvement of the chest, shoulders and upper arms was similar regardless of whether the exercises were done with free weights or a machine.

A muscle doesn’t “know” whether the source of resistance is a barbell, a machine or a cinder block. It’s no surprise, then, that the same exercises activate the same muscles when done with barbells as when done with a machine.

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Pimentel, I., et al. 2016. Smith machine vs. barbell: Ten repetition maximum loads and muscle activation pattern during upper body exercises. Journal of Exercise Physiologyonline, 19 (5), 86–92.

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AFM-Author-Brzycki Matt Brzycki , is the Assistant Director of Campus Recreation, Fitness at Princeton University. He has more than 30 years of experience at the collegiate level and has authored, co-authored and edited 17 books.

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