Holding a bar overhead requires a significant amount of interaction between your hips, core, back, and shoulders. Shoulders are actually the least of your worries. If you can hold your ribcage tall, core tight, fire your glutes, and stack the bar over your shoulder blades, the overhead hold becomes  a matter of stabilizing.

The work required to this is the same work required to maintain good posture – especially when running. Posture can quickly fail during a challenging run, which in turn makes the run more challenging. Maintaining good posture will help you stay light on your feet so you can run like the wind;)

Note: Tall posture is not the same as puffing out your chest and arching your lower back. What you want to do is tuck your tailbone under with firm glutes, naval to the spine, ribcage hollow and pulled up – the whole ribcage, not just the sternum – and the the top of your head (not your face) pulled up to the sky.