Preferred gait and walk–run transition speeds in ostriches measured using GPS-IMU sensors

Abstract

The ostrich (Struthio camelus) is widely appreciated as a fast and agile bipedal athlete, and is a useful comparative bipedal model for human locomotion. Here, we used GPS-IMU sensors to measure naturally selected gait dynamics of ostriches roaming freely over a wide range of speeds in an open field and developed a quantitative method for distinguishing walking and running using accelerometry. We compared freely selected gait-speed distributions with previous laboratory measures of gait dynamics and energetics. We also measured the walk-run and run-walk transition speeds and compared them with those reported for humans. We found that ostriches prefer to walk remarkably slowly, with a narrow walking speed distribution consistent with minimizing cost of transport (CoT) according to a rigid-legged walking model. The dimensionless speeds of the walk-run and run-walk transitions are slower than those observed in humans. Unlike humans, ostriches transition to a run well below the mechanical limit necessitating an aerial phase, as predicted by a compass-gait walking model. When running, ostriches use a broad speed distribution, consistent with previous observations that ostriches are relatively economical runners and have a flat curve for CoT against speed. In contrast, horses exhibit U-shaped curves for CoT against speed, with a narrow speed range within each gait for minimizing CoT. Overall, the gait dynamics of ostriches moving freely over natural terrain are consistent with previous labbased measures of locomotion. Nonetheless, ostriches, like humans, exhibit a gait-transition hysteresis that is not explained by steady-state locomotor dynamics and energetics. Further study is required to understand the dynamics of gait transitions.

The role of stride frequency for walk-to-run transition in humans

“…We performed this analysis on the data from Daley et al . 41 and found similar mean relative values of predicted and calculated walk-to-run transition stride frequencies for the ostriches. The values were 0.41 and 0.44, respectively.…”

“…Of note is that data on preferred gait as well as walk-to-run transition in ostriches were recently reported 41 . Thus, the authors reported mean values of freely chosen velocities during freely walking and running as well as the transition velocity.…”

“…In that perspective, it may not be surprising that the present suggestion of a role of stride frequency for walk-to-run transition apparently can be supported by data collected on ostriches by Daley et al . 41 .…”

Tyrannosaurus Rex Running? Estimations of Efficiency, Speed and Acceleration

“…Unfortunately, information about T. Rex traces is very limited. Moreover, to use formula (7), we need the maximal length of the running stride, which is much larger and happens much less often in comparison with the strides corresponding to the comfortable running (see, e.g., the data about ostriches in [11]). We can use the information about the relative stride referred to the leg length.…”

An exploratory clustering approach for extracting stride parameters from tracking collars on free ranging wild animals

“…Such a system needs to be able to remove periods of non-steady locomotion and segment the data into strides. Previous studies trained animals to move at steady speeds and removed nonsteady locomotion by using a threshold based on speed (Maes et al, 2008) and velocity heading (Daley et al, 2016). Stride segmentation has been carried out using supervised machine learning (Mannini and Sabatini, 2012;Pfau et al, 2008).…”