What should your arm swing look like?
Your arms and the way you swing them make a big impact on your run form and balance. If you trip, they’ll shoot out to brace your fall. If you have to jump up or over something, they’ll swing farther If you sprint, your arms pump more dramatically. If you’re navigating tricky terrain on the trail, your arms assume a life of their own, shooting out in all different directions to keep you upright. They just might shoot up high in the air when you cross that finish line.
As we mentioned above, your spine can flex, extend, bend side to side, and most importantly, rotate. In fact, every time your leg swings back behind you it adds a rotational force on the spine that, when resisted, helps bring your leg back forward through the gait cycle.
The faster you run, the more your arms swing in opposition to resist that rotation and channel it into forward movement. Your upper torso should remain straight as you do this and your shoulders should remain level with your chest pointed straight ahead. Your elbows should drive straight back behind you, while the size of your arm swing will be based on your speed and the rotational demands that come with it.