Cardiopreliminary · human data
Arms add less than 1% of the push in running
A simulated running stride credits arm motion with under 1% of the peak acceleration of the body's centre of mass. The arms still had a job: they counterbalanced the vertical angular momentum of the legs, while the calf muscles supplied propulsion and support late in stance and the quadriceps did the early braking.
What it shows: Modelling rather than measurement: a simulated running gait cycle driven by 92 simulated muscles of the legs and torso, which shows what the mechanics imply, not what happens when a real runner changes their arm swing. It also describes a single gait pattern, so faster running, hills and fatigue are untested here.Study · J Biomech