shutterstock_105840977-vertEmily L. Lawrence, PhD

Director of Biomechanics

Sports Academy


Mechanics uses traditional engineering principles to understand the response of physical bodies to applied forces or displacements and biomechanics uses those same principles to analyze biological systems. Sports biomechanics is a sub-section of biomechanics that, as the name implies, applies biomechanics to optimize sports performance. Recently, several groups have begun to apply sports biomechanics to quantify the roles of the upper and lower extremities in sprint performance1,2,3,4. A three-dimensional (3D), 92-muscle computational model of human gait revealed that the arms have a minimal contribution to forward propulsion (~1%), but do serve to counterbalance the vertical angular momentum of the lower extremities, thus increasing stability1,2,4. Similarly, experimental studies of sprint biomechanics reveal that arm swing improves stability by (i) counteracting the angular momentum produced by the swinging legs about the vertical axis and (ii) reducing the side-to-side motion of the center of mass. Moreover, it was suggested that these biomechanical effects also reduce energetic costs of running, which was later supported other groups who reported a 4% increase in the energetic cost of running without arm swing3. These studies highlight the benefits of arm swing during ambulation for increasing overall stability and reducing energy expenditure, which are critical for optimal sprint performance. However, inefficient arm swing biomechanics will not only fail to increase stability and decrease metabolic costs while sprinting, it will actually exacerbate the problem. Therefore, it is of interest to runners, particularly sprinters, to incorporate devices designed to train optimal arm swing biomechanics in order to improve overall performance.

“The KlickSpeed device provides a simple and effective way to teach athletes proper arm swing mechanics for running through a combination of muscle memory and auditory cues, creating an ideal training situation.” –Emily L. Lawrence, PhD


[1] Pontzer, Herman, et al. “Control and function of arm swing in human walking and running.” Journal of Experimental Biology 212.4 (2009): 523-534.

[2] Bruijn, Sjoerd M., et al. “The effects of arm swing on human gait stability.”Journal of Experimental Biology 213.23 (2010): 3945-3952.

[3] Arellano, Christopher J., and Rodger Kram. “The effects of step width and arm swing on energetic cost and lateral balance during running.” Journal of Biomechanics 44.7 (2011): 1291-1295.

[4] Hamner, Samuel R., Ajay Seth, and Scott L. Delp. “Muscle contributions to propulsion and support during running.” Journal of Biomechanics 43.14 (2010): 2709-2716.


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