Participant and agility drill experimental setup and exemplar horizontal foot trajectory smoothing.

<p>(A) Photograph of the IMU selected for this study. (B) Participant wearing foot-mounted IMUs taped to the top of both shoes, additional body-worn sensors, and military accessories (because this study was part of an experiment designed to assess soldier performance of an outdoor obstacle course). (C) Agility drill setup with exemplar high performer (left) foot x-y trajectory: pre-smoothed (magenta) and and-post smoothed (blue). Cones (orange circles) are separated with 5m distance.</p

Turn phase ground reaction-based performance metrics grouped by agility drill time.

<p>Boxplots of ground reaction-based performance metrics for each trial evenly grouped by sorting agility drill time as the performance outcome. The following metrics are displayed, calculated during turn phases: <b>(A)</b> Average horizontal ground reaction magnitude (body mass normalized), <b>(B)</b> average percent horizontal ground reaction normal to the foot trajectory, <b>(C)</b> cumulative footfall duration, and <b>(D)</b> “force generation” metric. Asterisks indicate statistically significant differences between performance groups via post-hoc mean rank test (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188184#pone.0188184.t001" target="_blank">Table 1</a>).</p

Agility drill time and average turn radius performance metric grouped by agility drill time.

<p>Boxplots of <b>(A)</b> agility drill time and <b>(B)</b> average turn radius for each trial evenly grouped by sorting agility drill time as the performance outcome. Asterisks indicate statistically significant differences between performance groups via post-hoc mean rank test (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188184#pone.0188184.t001" target="_blank">Table 1</a>).</p

Summary of statistical results.

<p>Summary of statistical results.</p

Exemplar average horizontal foot trajectory curvature.

<p>Average foot path curvature as a function of time for an exemplar high performer. Agility drill time is the time that elapses between a performer passing cone 1 and passing cone 5. The approximate time that the performer circumvented each cone is represented with numbered orange circles.</p

Tangential acceleration range and body speed performance metrics grouped by agility drill time.

<p>Boxplots of average estimated <b>(A)</b> tangential acceleration range and <b>(B)</b> body speed for each trial evenly grouped by sorting agility drill time as the performance outcome. Asterisks indicate statistically significant differences between performance groups via post-hoc mean rank test (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188184#pone.0188184.t001" target="_blank">Table 1</a>).</p

Exemplar body speed and tangential acceleration estimates.

<p><b>(A)</b> Body speed and <b>(B)</b> tangential acceleration estimates vs. time for an exemplar high performer. The approximate time that the performer circumvented each cone is represented with numbered orange circles. The tangential acceleration range is represented by the vertical gray bars between successive cones.</p

Exemplar right foot horizontal trajectories with body speed.

<p>Exemplar right foot horizontal trajectories with body speed (color scale) for a <b>(A)</b> high performer and a <b>(B)</b> low performer.</p