Mace Swinging Physics: Why back swing form is so important to prevent injuries

Check out the video above to see the physics behind why your back swing form is so important to prevent injuries.

Keeping the mace close to ones body is always going to be important for swing efficiency by keeping the orbit of the mace nice and regular (when the mace is thrown off from its regular orbit on a vertical plain, extra energy is required to pull it back onto its regular path), but by allowing the mace to stray away from the body, particularly in the case of keeping your hands too high in the back swing, also puts a lot of additional stress on the shoulder and elbow joints.

In the above video, I start by using frame by frame analysis to calculate the centripetal force the mace, 9.5kg in this case, is exerting on my body during the back swing for both the hands high and hands low form, (you can read more about the role of centripetal force in mace swinging and how it is calculated HERE):

For this 9.5kg mace, the resultant total forces (centripetal force + the weight of the mace), were calculated at 24.9kg for the hands high form and 26.2kg for the hands low form, interestingly the force is actually higher with the hands low form, this is due to the mace having further to fall under gravity from the casting motion and therefore having a higher velocity, but this is not the whole story...:

I then analyse the angles of the shoulder and elbow joints to calculate the resultant torques on each joint:

As you can see the resultant torque on the shoulder joint is significantly higher with the hands high form, 51 vs 30Nm! It's also worth noting with the hands high form the shoulder is also placed into severely more extension, 86° vs 62°,  again putting the shoulder joint under even more stress.

This is why you might have heard the expression "keep your hands low on the back swing", it's to protect your shoulders and elbows! And if you are having difficulties getting your hands down low on your backswing, it's probably worth starting to work on your tricep and thoracic spine mobility!