Why almost everyone is wrong about the bench press...

If you could pick only two exercises to train your upper body, there's a good chance that the bench press would feature on your list, right?

Despite its popularity, there seems to be an endless debate about the effects of bench press variations on muscle activity in the chest, shoulders, and arms.

Bench press

Many trainers believe that several variations, such as the incline, flat, and decline bench press are necessary to develop your chest fully. According to conventional wisdom, the decline bench press preferentially activates the sternocostal head of the pectoralis major (the lower chest). The incline bench press is used to develop the clavicular head (the upper chest).

The spacing of your hands also affects muscular activity in your triceps (the back of your arm), deltoids (shoulders), and pectorals (chest). A wider grip is supposed to place a greater demand on your chest, while a narrow grip emphasizes the triceps.

To clear up some of the confusion regarding the bench press, a research team from the University of Queensland tested the effects of variations of the bench press on muscular activity in the upper and lower chest, shoulders, and triceps [2].

The different variations of the bench press measured were as follows.

• Flat bench press.

• Incline bench press (40 degrees above horizontal).

• Decline bench press (18 degrees below horizontal).

• Military press (vertical).

Two different hand positions - wide and narrow - were also tested. When using the narrow grip, subjects had their hands positioned directly above the shoulders. The wide spacing involved positioning the hands approximately twice shoulder width.

Limitations

Before you continue, it's worth pointing out that this study used the Smith machine, rather than a free bar. Research shows greater muscle activity during the bench press when free weights are used, rather than a machine [2].

Moreover, if you watch an experienced trainee performing the bench press, you’ll notice that they don’t push the bar straight up and down. Instead, the bar moves up and slightly towards the head.

Note too, that different muscles dominate at different stages of the bench press. For instance, the chest muscles dominate during the first half of the movement, as the bar is being pressed from the chest. Once the bar is past half way, the triceps assume greater importance.

In addition, muscular activity was assessed only during the LIFTING phase of the movement (as the bar was moved from the chest to arms length). However, the study still provides a valuable insight into how different variations of the bench press affect muscular activity in the chest.

Here's what the results showed:

LOWER CHEST (Sternocostal head)

• Military press
  The lower chest showed very little activity during the military press.

• Incline bench press
  Muscular activity was greatest using the wide rather than the narrow grip.

• Flat bench press
  This movement produced the greatest activity in the lower chest. There was little difference between the wide and narrow grip.

• Decline bench press
  Muscular activity in the lower chest was reduced during the decline compared to the flat bench press.

UPPER CHEST (Clavicular head)

• Military press
  Activity of the upper chest was at its lowest during the military press.

• Incline bench press
  This movement produced the greatest activity in the upper chest.

• Flat bench press
  Muscular activity during the flat bench press was only SLIGHTLY less than the incline bench press.

• Decline bench press
  Activity in the upper chest was slightly greater during the decline bench press compared to the military press.

FRONT SHOULDER (Anterior deltoid)

• Military press
  This movement produced the greatest activity in the front of the shoulder, with very little difference reported between the wide and narrow grip.

• Incline bench press
  Results showed slightly greater activation in the wide, rather than the narrow grip.

• Flat bench press
  The anterior deltoid worked harder during the narrow, compared to the wide grip.

• Decline bench press
  Again, the anterior deltoid worked harder during the narrow, rather than the wide grip.

So, what's the bottom line?

To maximize development in the lower chest, use a flat bench press with a wide grip. To emphasize the upper chest, the incline bench press with a shoulder width grip appears to be most effective. Based on the findings of this study, the decline bench press offers little advantage compared to the incline or flat bench press.

Most people are able to lift the most weight during the decline bench press with a wide hand spacing. This shouldn't come as any great surprise, as the distance the bar must travel during the decline bench press is much less compared to the flat position. This also explains why arching your back during the bench press allows you to lift more weight.

If you find that your shoulder hurts during the bench press, try using a very slight decline bench. This seems to reduce the load on the shoulder without compromizing the amount of muscular work performed by the chest.

References
1. Barnett, C., Kippers, V., & Turner, P. (1995). Effects of variations of the bench press exercise on the EMG activity of five shoulder muscles. Journal of Strength and Conditioning Research, 9, 222-227
2. McCaw, S.T., & Friday, J.J. (1994). A comparison of muscle activity between a free weight and machine bench press. Journal of Strength and Conditioning Research, 8, 259-264