Introduction

The great SICB is holding an annual conference, usually in the beginning of January each year. Last year (January 2021), this was fully online, and I took the chance to contribute my first major online conference talk.

I set myself two major challenges:

(i) I wanted to use the online format as good as possible, carefully taking my first steps in video recording and editing.

(ii) I intended to finish off my long theoretical exploration of inverse dynamics with actual calculations.

My project and my supervisors were screaming for results, but I had trouble getting forces and animal masses to match. So I submitted an abstract about the swing phase.

This was a great experience, which got me deep down the rabbit hole of mechanical (joint) energy. Yet the data remained somewhat unfinished, and I went off exploring CT technology to fix it (see here).

Methods

I tried to deviate from the standard “zoom recording” which was recommended, got the excellent “zoom H5” audio recorder instead and went out to Hobokense Polder with little more than a script in my head. I recorded many repetitions, gradually got better, but still faced the challenge of overdubbing outdoor recording with studio text. Well… I learned on the way. It was fun.

Results

Enjoy watching!

(also available on odysee.)

Discussion

I regret that I am too busy to join this year. Enjoy the conference, happy SICB, everyone!

As always, any questions and feedback are welcome. (falkmielke.biology@mailbox.org)

Abstract

Terrestrial locomotion necessarily involves a stance phase (to hold the weight) and a swing phase (to advance the stance positions). Of those, the latter is sometimes supposed to be partially passive, i.e. negligible in terms of energy expenditure. For example, the swing phase has been described as “ballistic” (cf. Mochon and McMahon, 1980), which implies that the limb is “shot off” at given conditions, then passively moves, prior to impact. However, such sophisticated locomotor patterns require precise coordination to be energy efficient. There is evidence that young individuals fail to coordinate efficient swings. We present data from locomoting piglets (age 1-5 days) to measure how energy efficient their swing actually is. Using recordings from biplanar x-ray, we are able to quantify inverse dynamic balances and energetics at the joint level in high detail. Our data offers insights into a crucial developmental phase of these animals, showing that “swinging it right” takes some practice.