A blog by runners. For runners.

Don’t be a T-Rex: proper running arm form


The Tyrannosaurus Rex is embedded in my childhood consciousness thanks to Jurassic Park. I can still feel the Dolby Digital thunderclap of its footsteps reverberating in my bones and John Hammond casually stating, “Well, we clocked the T-Rex at 32 miles an hour.”

Quite the impressive speed but recent studies indicate perhaps T-Rex couldn’t chase down its prey as quickly as we saw on the silver screen. Its hulking body and muscular frame was built for power, not speed. As a child, I remember peering up at the T-Rex skeleton at the Museum of Natural History and wondering why its arms were so disproportionately small. Sure, it legs boast Olympian musculature, but legs alone can’t carry a body quickly and efficiently. Just try running a mile with your hands in your pockets.

As runners, we swing our arms to counter the propulsion of our legs. The faster we swing our arms, the faster our cadence.

But when our bodies are in motion, we enter defense mode. We’re fighting gravity, burning fuel, chasing down competitors, dodging cars that creep into crosswalks. We’re counting steps, breathing to a rhythm, repeating mantras, taking in the scenery. As we fatigue, we tend to focus on our legs, foot strikes, current pace, breathing. We often forget to swing our arms, just like a nervous speaker forgets to breathe. As our arms disengage, our form and efficiency follow. But to maximize your running economy, you must bend your elbows at 90 degrees.

Achieve “better” arm form

  • Relax your hands. Clenched hands lead to stiff arms, locked shoulders, and a tight neck. Open and close your fingers and shake out your arms to stay loose.
  • Engage your elbows. “Push” your elbows back to increase your horizontal swing. More horizontal movement leads to more power – AUURRHHH!
  • Know your trigonometry. If your arms fall at obtuse angles, greater than 90 degrees, your hands are more likely to dip below your hips. Vertical movement leads to a loss of power. If your arms rise at acute angles, less than 90 degrees, your hands are more likely to reach above your shoulders, an angle better equipped for climbing a rope. Aim for 90 degrees.

Try it out 
On your next run, imagine you are pulling a rope in a mighty game of tug-of-war — the faster you pull, the faster your feet will cover precious ground; the deeper you pull back your elbows, the more power you will generate with each swing.

Keep in mind, however, our adaptable bodies don’t uniformly respond to a one size fits all approach. In the 1970s, Biomechanist, Peter Cavanagh, enlisted the help of decorated marathoner, Bill Rogers, in an experiment. Cavanagh wondered if “correcting” Rogers’ trademark across the body arm swing to a more traditional form would improve his world-class performance. Surprisingly, this “correction” actually increased the effort needed for Rogers to run at the same pace. It seems that Rogers adapted to the idiosyncrasies of his body.

Should you try to mimic Rogers’ trademark arm swing? No – if it’s not broken, don’t fix it. But if you are eager to try something new and attain a more efficient form — experiment.

Written by Stephen Marcin.

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