Biology subjects

Moretto, P.

Publications and source records attributed to Moretto, P..

3 recordsLinked to original sources

bioRxiv2023

The impact of collective load transport on the individual walking

Collective handling is a collaborative strategy that involves two or more people in carrying out load transport. Different positions can be adopted, depending on the handle locations of the transported load, external constraints and the capacities of the carriers. The most adopted collective transport in our daily life is stretcher type transport. However, very little research has focused on the kinematic modifications caused by this type of transport. This research aims to evaluate and quantify the modifications of the locomotor pattern of stretcher transport. Our results highlighted a modification of walking parameters (step length, duration of the walking cycle, speed of execution, etc.), an increase in energy cost but above all a modification of the walking pattern with a reduction in joint range of motion. These results could be used to establish new recommendations for musculoskeletal disorders.

biophysics↗

bioRxiv2021

Biomechanical effects of the addition of a precision constraint on a collective load carriage task

1Team lifting is a complex and collective motor task that possesses both motor and cognitive components. The purpose of this study was to investigate to what extent the biomechanics of a collective load carriage is affected when a dyad of individuals is performing a carrying task with an additional accuracy constraint. Ten dyads performed a first condition in which they collectively transported a load (CC), and a second one in which they transported the same load while maintaining a ball in a target position on its top (PC). The recovery-rate, amplitude, and period of the center-of-mass (COM) trajectory were computed for the whole system (dyad + table = PACS). We analyzed the forces and moments exerted at each joint of the upper limbs of the subjects. We observed a decrease in the overall performance of the dyads when the Precision task was added, i.e., i) the velocity and amplitude of CoMPACS decreased by 1,7% and 5,8%, respectively, ii) inter-subject variability of the Moment-Cost-Function decreased by 95% and recovery rate decreased by 19,2% during PC. A kinetic synergy analysis showed that the subjects reorganized their coordination in the PC. Our results demonstrate that adding a precision task affects the economy of collective load carriage. Notwithstanding, the joint moments at the upper-limbs are better balanced and co-vary more across the paired subjects during the precision task. Our study results may find applications in domains such as Ergonomics, Robotics-developments, and Rehabilitation.

bioengineering↗

bioRxiv2019

Walking kinematics in the polymorphic seed harvester ant Messor barbarus: influence of ant size and load carriage

Ants are famous in the animal kingdom for their amazing load carriage performances. Yet, the mechanisms that allow these insects to maintain their stability when carrying heavy loads have been poorly investigated. Here we present a study of the kinematics of loaded locomotion in the polymorphic seed-harvesting ant Messor barbarus. In this species big ants have larger heads relative to their size than small ants. Hence, their center of mass is shifted forward, and the more so when they are carrying a load in their mandibles. We tested the hypothesis that this could lead to big ants being less statically stable than small ants, thus explaining their lower load carriage performances. When walking unloaded we found that big ants were indeed less statically stable than small ants but that they were nonetheless able to adjust their stepping pattern to partly compensate for this instability. When ants were walking loaded on the other hand, there was no evidence of different locomotor behaviors in individuals of different sizes. Loaded ants, whatever their size, move too slowly to maintain their balance through dynamic stability. Rather, they seem to do so by clinging to the ground with their hind legs during part of a stride. We show through a straightforward model that allometric relationships have a minor role in explaining the differences in load carriage performances between big ants and small ants and that a simple scale effect is sufficient to explain these differences.

animal behavior and cognition↗