Smith Machine versus Free Weight Bench: A battle of goals

Weight rooms continue to add new machines and tools to allow exercisers to work out in a variety of ways. Most weight rooms have many different machines and exercises that can work the upper body. The bench press, works the pectoralis major, triceps barchii and anterior deltoid, with stabilization by the medial deltoid.  A variety of equipment and a large number of options such as a free weight bench press, seated chest press, or Smith Machine bench press can be used to perform a bench press exercise.

But how do these machines and exercises fare in regards to last week’s blog “Training on Unstable Surfaces: Superior to Traditional Strength Training?” Many experienced lifters accept the free-weight bench press as the ideal method for maximal upper body strength gain. The Smith Machine, such as the one in the picture above¹, offers a safer and more controlled means of training the same muscles for inexperienced lifters.

The Smith Machine is a weight lifting rack with fixed rails that the bar moves along. Most can be used for a variety of exercises by moving a bench into or out of the rack. In addition, many have catch points for the bar to stop at or rest on to increase safety.

But what happens to muscle activation during lifts on the Smith Machine versus the free weight bench press? A recent study² found that there were no significant differences in muscle activation of the pectoralis major or anterior deltoid for experienced and non-experienced lifters. The study looked at any a variety of loads (70% 1RM & 90% 1RM) for both groups. There was a significant difference in muscle activation by the medial deltoid. The free weight bench press required more activation of the medial deltoid. This muscle helps stabilize the shoulder joint during the resisted phase of the free weight bench press.

Since the Smith Machine bench press required less stabilization, you might think that this would allow for greater loads to be used. This was not found in the study. “It may be that the unnatural bar path of the smith machine forces the subjects to press in an unnatural linear path instead of the reverse ‘C’ observed during free weight bench press, subsequently hindering optimal force production.”

This confirms that both exercises are good options in the weight room, but depend on the goal of the exerciser. These results suggest that the free weight bench press may lead to increased requirement for stabilization about the shoulder joint from muscles such as the medial deltoid. Exercisers should determine if this is an area in need of development when choosing an exercise and working towards their training goal.

Activities such as basketball, baseball, tennis, racquetball, hockey or volleyball require movement and stability by the glenohumeral joint. If preparing for these activities then the free weight bench press might be the best exercise. But as with any exercise, machine or tool in the weight room, it all goes back to the purpose or goal.

¹Photo permission from: Free Motion Fitness, www.freemotionfitness.com. 03/25/10.

²Schick, EE, Coburn, JW, Brown, LE, Judelson, DA, Khamoui, AV, Tran, TT, and Uribe, BP. A comparison of muscle activation between a Smith machine and free weight bench press. J Strength Cond Res 24(3): 779-784, 2010.

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