Shoulder Flexion Biomechanics

In this blog, we’re going to briefly explore the biomechanics of the landmine press, which is one of many options that rehabilitation professionals have to expose their clients’ shoulder to load as they move through “shoulder” flexion.

A key concept here is understanding that the shoulder represents the interaction between many individual segments (rib cage, thoracic spine, clavicle, scapula, humerus).

We’ve spoken about the concept of joints vs segments before within the context of the shoulder, and why we feel it’s important to describe the behaviour of the individual segments relative to the task that is being performed. See “scapular variability during shoulder elevation” for more information.

The Landmine Press
A landmine press allows us to add resistance to humeral flexion and couple that with elbow extension like many other vertical pressing options. But, the dynamics of the barbell here reduces the range of humeral flexion relative to a more vertical pressing action.

The grip & midrange forearm position also reduces the rotational challenge on the humerus, and this provides a great foundation for us to influence what’s happening between the humerus & scapula.

As described in previous blogs, not all shoulder elevation is the same. We can elevate the shoulder in the sagittal plane, scapular plane, or frontal plane.

In the first image shown, you can see that the humerus is pre-positioned in humeral external rotation. An easy way to identify this is through the bicep and tricep. If the bicep is facing towards the sky when the humerus is in the sagittal plane, the humerus is externally rotated. If the bicep is facing medially, the humerus is internally rotated.

This is important during the landmine press, because if we want to maintain the resistance to humeral flexion and keep the humerus in the sagittal plane, then the humerus must stay in external rotation (particularly during the mid range of the pressing action). 

If the humerus internally rotated here, the barbell would fall to the inside and would be more of an external rotation resisted exercise vs resisting humeral flexion.

Scapular behaviour

What does the scapula have to do in order to position the humerus into the sagittal plane?

It needs to protract and internally rotate to point the glenoid cavity more forward. In the image with humeral external rotation, you can see how the scapula has gilded around the rib cage to facilitate that humeral position.

This is naturally going to be a much more challenging scapular & humeral relationship for those who have local limitations around the shoulder complex, but an important one to work towards if your goal is to promote more segmental variability

Shifting into the scapular plane

Another strategy often demonstrated is a shifting of the humerus into the scapular plane, and there’s many potential reasons for this (see image).

This does not represent a “bad” strategy, but it does represent less of a variability challenge to the scapular & humeral relationship.

In the image shown, you can see how the tricep is beginning to face more laterally (bicep more medially), and this demonstrates less humeral external rotation, and a shift away from the sagittal plane. 

When the humerus shifts into the scapular plane, this may be secondary to an inability of the scapula to protract & internally rotate to allow the humerus to position itself in the sagittal plane.

As a result, the humerus may position itself closer to the scapular plane during the resisted press (again, nothing wrong with this unless you’re trying to promote more segmental variability).

This may also be used as a strategy simply to produce more force because the scapular plane reduces the need for relative humeral rotation, and allows the scapula to contribute to that overhead pressing action. 

In the first strategy, with humeral external rotation, the resistance is being concentrated through the humerus. On top of this, the humerus (external rotation) and scapula (internal rotation) are positioned in opposite rotational directions, and this reduces their ability to “help each other” move in the SAME direction to produce force.

In the second image, the scapular plane reduces this rotational demand and the humerus & scapula have more freedom to drive in the SAME direction.

Wrapping up

A solid understanding of biomechanical relationships during different tasks is massively beneficial to allow you to manipulate how you’re applying stress to muscles & joints / segments. 

It’s also important to have clarity in your intention when utilising this loading strategy. Are you trying to promote variability between segments while simultaneously allowing tissues to build capacity to forces, or are you trying to build more maximal force production capacities while reducing the variability demand?

For us, this is incredibly important when it comes to rehabilitation, especially when we consider how those experiencing pain and/or movement limitations will typically demonstrate reductions in variability.

Does this mean biomechanics always matter when it comes to addressing pain? NO!

However, biomechanics along with an understanding of neurological features can certainly offer you a more robust framework to guide how you structure your loading and exercise strategies during rehabilitation.

Learn more 

Check out our online courses to learn more, and also keep an eye out for more exciting ways to learn with us as we move into 2024!