How human runners regulate footsteps on uneven terrain

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Abstract

Running stably on uneven natural terrain takes skillful control and was critical for human evolution. Even as runners circumnavigate hazardous obstacles such as steep drops, they must contend with uneven ground that is gentler but still destabilizing. We do not know how footsteps are guided based on the uneven topography of the ground and how those choices influence stability. Therefore, we studied human runners on trail-like undulating uneven terrain and measured their energetics, kinematics, ground forces, and stepping patterns. We find that runners do not selectively step on more level ground areas. Instead, the body's mechanical response, mediated by the control of leg compliance, helps maintain stability without requiring precise regulation of footsteps. Furthermore, their overall kinematics and energy consumption on uneven terrain showed little change from flat ground. These findings may explain how runners remain stable on natural terrain while devoting attention to tasks besides guiding footsteps.

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All data points are plotted in either the main text, the figure supplements, or source data attached to figures and tables.

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Nihav Dhawale

1Department of Mechanical Engineering and Materials Science, Yale University, New Haven, United States

Competing interests
The authors declare that no competing interests exist.
Madhusudhan Venkadesan

1Department of Mechanical Engineering and Materials Science, Yale University, New Haven, United States

For correspondence
m.venkadesan@yale.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-5754-7478

Funding

Human Frontier Science Program (RGY0091/2013)

Madhusudhan Venkadesan

The Wellcome Trust DBT India Alliance (NA)

Madhusudhan Venkadesan

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: The study was approved by the Institute Ethics Committee (Human Studies) of the National Centre for Biological Sciences, Bengaluru, India (TFR:NCB:15\_IBSC/2012), where the experiments were conducted. Informed consent was obtained by the experimenter N. Dhawale and M. Venkadesan, who are the authors of this manuscript. The procedure followed for seeking informed consent followed the steps that were approved by the Ethics Committee mentioned above.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.