Analysis of the bar path in bench press

Question

I wanted to do a deep analysis of the reason behind the ideal bar path in bench press.

There are many sources telling us that the ideal bar path is something like this (a J pattern on the way up, and a rounded pattern on the way down).

Let's do a gradual analysis and understand the reasons behind that.

Step 1: The proper ending point of the way up

The proper ending point of the way up is above the front delts. As written there, this minimizes the moment arm between the bar and the front delts. Hence, at the top, the front delts won't work so hard to keep the barbell in such a position. Hence, the front delts won't be the limiting muscle of bench press, which is good as we usually want to work primarily our chest.

Step 2: The proper starting point of the way up

The proper starting point, as written always there, is on about the middle chest. It can't be above the front delts as it will make the elbows flare and cause shoulder impingement.

Which is the precise point is debated, as far as I'm concerned. Some sources say it is the nipple, others it is a generic point between the nipple and the Xiphoid Process.

Step 3: The proper bar path The proper bar path should connect the points 1 and 2 previously mentioned in the best way. A first attempt is the shortest path, i.e. a diagonal path:

However, it is not the best one. The best path is said to be that shown in the first picture.

Now, my questions are:

1) The bar above the front delts at the bottom makes flare the elbows and cause shoulder impingement. Why isn't it a problem at the top (where the bar is above the shoulders)?

2) Which may be a possible reason for choosing a curved bar path, which is longer than a diagonal bar path?

3) Which may be an intuitive reason for choosing different bar paths for the way up (concentric) and down (eccentric)?

Answer 1

1. The bar above the front delts at the bottom makes flare the elbows and cause shoulder impingement. Why isn't it a problem at the top (where the bar is above the shoulders)?

It's not only debatable whether the "guillotine" style bench press, in which the bar is lowered straight down over the collarbones, causes shoulder impingement, but the very existence of shoulder impingement has been brought into question¹. That said, the main complaint about the guillotine style bench is that at the bottom of the movement, the shoulder (glenohumeral joint) must move into a position of extreme internal rotation, so there is a concern that this could cause damage to the external rotators of the rotator cuff (teres minor, infraspinatus, and supraspinatus). At the top of the bench press, the shoulder is roughly in the middle of its internal-external rotation range, so that concern disappears.

2. Which may be a possible reason for choosing a curved bar path, which is longer than a diagonal bar path?

There is no inherent drawback to choosing a longer bar path. In terms of energy that must be applied to the bar, vertical distance travelled is all that matters. As an example, consider two paths to reach the top of a 500m tall mountain. One is a switchback road that is 5km long in total but not that steep. The other is a 500m vertical cliff face. Which is easier to ascend?

The only reason why, in some lifts, a non-straight bar path is disadvantageous, is if that bar path causes you to move into positions in which you are weaker. For example, a deadlift path path in which the bar swings forwards on the way up is less efficient not because it is non-vertical, but rather because when the bar swings forwards it puts you into a position where greater hip and back strength is needed to lift it. Or in the bench press, if the bar drifts too far down towards your belly, then the moment arm to your shoulders increases and your deltoids need to do more work.

Therefore, a curved bar path can be advantageous if it allows you to use stronger muscles during the harder parts of the lift. In the case of bench press, bringing the bar up towards your face as it leaves the chest reduces demands on the deltoids, and puts the arms in a position where the much stronger pectorals are contributing the most to moving the bar.

3. Which may be an intuitive reason for choosing different bar paths for the way up (concentric) and down (eccentric)?

Reasons would include:

• Muscular demands are lower on the way down because the bar can be decelerated by impact with the rib cage, so you don't need to rely on the pecs as much. Whereas if a J-shaped path were used on the way down, the pectorals would need to slow the bar to prevent it dropping all the way to the collarbones, and then you'd have to move it down to the lower sternum after it has been slowed.
• Muscles are stronger in eccentric movements than concentric, so loading the deltoids on the way down isn't as much of a concern as on the way up.
• Using the deltoids more on the way down allows strength in the pectorals to be preserved for the harder concentric phase.