You can become a more efficient runner by making some adjustments to your arm swing and carriage. Easy, efficient arms can improve your form and running economy by reducing wasted energy while you run. Ironically, however, if you over-think your form, you wind up with stiff, mechanical, and energy-inefficient running. So, what you should focus on is developing a natural efficient arm movement. But what, exactly, constitutes an efficient arm swing and carriage?
For years, coaches and athletes commonly agreed that runners’ arms should swing front-to-back, with their elbows bent at roughly 90 degrees, and their shoulders relaxed. The received wisdom back in the day insisted that runners had to avoid crossing their arms in front of their chest as they ran. Coaches believed that this side-to-side motion wasted energy and undermined forward propulsion. Though this is generally accepted as common knowledge in the running community, it turns out to be untrue.
The good news is that as long as you swing your arms and keep your shoulders relaxed, it really doesn’t matter if there is some movement across your chest. Dr. Rodger Kram, the author of a recent, influential study on arm swing concluded that “Most people will settle into the arm swing that is most efficient for them.” This makes some intuitive sense, since some of the best runners have had notable across-the-chest arm swing. In fact, if you take an internet tour of top distance runners, you might actually have difficulties finding a runner who doesn’t do some arm crossing.
If there is considerable variation in what constitutes normal arm swing, why should we concern ourselves? On one hand (see what I did there?), a relaxed and natural arm swing can result in more efficient running. For the most part, just do what feels natural –– if it works for you, it’s not wrong.
On the other hand, however, one needs to be able to draw upon a more aggressive arm swing to activate the legs when they are fatigued. It is almost a biomechanical impossibility to keep one’s legs at a slow cadence or turnover while aggressively pumping one’s arms. Arms and legs work reciprocally, a backward arm swing on one side enhances the same-sided leg drive. This is why pumping your arms at the end of a race, even if you are exhausted, can improve your finish. This is definitely something that you will have to think about as you run. (It’s a good element to work on during speed work repeats.)
The takeaway: Relax about how to swing your arms. Think more about when to exaggerate the swing –– when you want to pick up your tempo and overcome fatigue.