Changes in the motor behaviour during a familiarisation protocol to a soft back exoskeleton - Archive ouverte HAL
Communication Dans Un Congrès Année : 2022

Changes in the motor behaviour during a familiarisation protocol to a soft back exoskeleton

Résumé

Back exoskeletons, defined as wearable structures that give an assistive torque to one or multiple joints, can prevent from low back disorders (LBD) during stoop lifting tasks (1). Results in the literature about benefits and disadvantages are inconsistent (2), possibly due to the lack of familiarisation to the use of exoskeletons (3). Thus, this study evaluated the effect of familiarisation to a back exoskeleton to define changes in the motor behaviour. Ten males (1.78 +/- 0.04 m, 69.9 +/- 5.8 kg, 22.3 +/- 2.4 years) performed 6 sessions of 1-h familiarisation to a CORFOR® soft back exoskeleton within 2 weeks. This familiarisation protocol consisted in several manual handling tasks and precision tasks involving trunk bending. Measurements were carried out at the beginning of the first session and at the end of each session, during which participants were asked to execute 10 repetitions of a lifting task in the sagittal plane using the stoop technique (8 kg; 15 cycles / minute). A timed precision task, involving the whole body to move a ring along a weaving metallic tube without touching it, was used to assess a performance score of the participant's ease with the exoskeleton. Prior to this CORFOR® familiarisation protocol, participants get used to stoop and precision tasks during 3 sessions of 20min. The level of muscle activity (RMS) was calculated from electromyographic (EMG) recordings of erector spinae (ES) and rectus abdominis (RA) muscles. Ellipse area of the centre of pressure displacements during the lifting task was calculated as a marker for postural stability. Back curvature was evaluated through 3D kinematics measurements yielding lumbar (LF) and thoracic (TF) flexions in the sagittal plane. A repeated measures ANOVA with Tuckey's HSD post-hoc tests were performed to assess the effect of the familiarisation protocol on the evolution of the motor behaviour. Main effect of familiarisation was observed on performance score (p<0.001) and ellipse area (p=0.01). Post-hoc tests showed that sessions 3 to 6 were different (p<0.05) from the other sessions for these variables. There was no main effect of familiarisation on EMG RMS (ES: p=0.63; RA: p=0.24) or back curvature (LF: p=0.12; TF: p=017). Changes in performance score and ellipse area suggested that the motor behaviour measured in the early stages of the participant's experience with the exoskeleton might not be representative of the longterm motor behaviour. This must be taken in consideration for the interpretation of the results of studies that investigated the effects of back exoskeleton without familiarisation. However, EMG and back curvature did not show any evolution across sessions. Accordingly, it seems that muscular and LBD possible benefits of the use of the exoskeleton do not change with practice.
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Dates et versions

hal-03954526 , version 1 (26-01-2023)

Identifiants

  • HAL Id : hal-03954526 , version 1

Citer

Arthur Favennec, Julien Frère, Guillaume Mornieux. Changes in the motor behaviour during a familiarisation protocol to a soft back exoskeleton. ECSS 2022 - 27th Annual Congress of the European College of Sport Science (ECSS), European College of Sport Science, Aug 2022, Sevilla (Spain), Spain. ⟨hal-03954526⟩
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