Visual feedbacks influence short-term learning of torque versus motion profile with robotic guidance among young adults.

Robotic assistance can improve the learning of complex motor skills. However, the assistance designed and used up to now mainly guides motor commands for trajectory learning, not dynamics learning. The present study explored how a complex motor skill involving the right arm can be learned without suppressing task dynamics, by means of an innovative device with robotic guidance that allows a torque versus motion profile to be learned with admittance control. In addition, we assessed how concurrent visual feedback on this profile can enhance learning without creating dependency, by means of a fading procedure (i.e., feedback reduction across trials). On Day 1, a Control group performed an acquisition session (6 blocks) featuring concurrent visual feedback, while a Fading group performed the session with a gradual reduction in feedback (from 100% to 0% over the 6 blocks). On Day 2, both groups performed a block first without feedback (i.e., Transfer test), then with feedback (i.e., Retention test). Results revealed that on Day 1, movement rehearsal induced a significant improvement in spatiotemporal parameters for the Control group, compared with the Fading group. On Day 2, the opposite was found when this visual feedback was removed, as the Fading group performed significantly better than the Control group on the Transfer test. Vision allows a relationship to be established between the required torque and the motion profile. Its suppression then forces the processing of more intrinsic information, leading to the development of a stable internal representation of the task.

New approaches for assessing childbirth positions.

BACKGROUND: An overview of labor based only on epidemiological data cannot identify or explain the mechanisms involved in childbirth. Data about the position that women should take in giving birth are discordant. None of the studies of birth positions adequately define or describe them or their biomechanical impact (pelvic orientation, position of the back). The measurement of the effect of one position relative to that of another requires precise definitions of each position and of their maternal biomechanical consequences, as well as safe measurement methods. METHODOLOGY: We have developed a system to analyze the position of labor by quantifying the posture of the woman's body parts (including thighs, trunk, and pelvis), using an optoelectronic motion capture device (Vicon™, Oxford Metrics) widely used in human movement analysis and a system for measuring the lumbar curve (Epionics spine system). A specific body model has also been created to conduct this biomechanical analysis, which is based on external markers. With this methodology and model, it should be possible to define: (1) the hip joint angles (flexion/extension, abduction/adduction, internal/external rotation); (2) the ante/retroversion of the pelvis; (3) the lumbar curve. DISCUSSION: This methodology could become a reference for assessing delivery postures, one that makes it possible to describe the relation between the postures used in the delivery room and their impact on the pelvis and the spine in an integrated and comprehensive model. TRIAL REGISTRATION: No. Eudract 2013-A01203-42.

[Changes in pelvic organ mobility and ligamentous laxity during pregnancy and postpartum. Review of literature and prospects]. / Modifications de la statique pelvienne et de la laxité ligamentaire pendant la grossesse et le post-partum. Revue de la littérature et perspectives.

INTRODUCTION: The role of pregnancy in pelvic floor disorders occurrence remains poorly known. It might exist a link between changes in ligamentous laxity and changes in pelvic organ mobility during this period. Our objective was to conduct a non-systematic review of literature about changes in pelvic organ mobility as well as in ligamentous laxity during pregnancy and postpartum. METHODS: From the PubMed, Medline, Cochrane Library and Web of Science database we have selected works which pertains clinical assessment of pelvic organ mobility (pelvic organ prolapse quantification), ultrasound assessment of levator hiatus and urethral mobility, ligamentous laxity assessment during pregnancy and postpartum. RESULTS: Clinical assessments performed in these works show an increase of pelvic organ mobility and perineal distension during pregnancy followed by a recovery phase during postpartum. Pelvic floor imaging shows an increase of levator hiatus area and urethral mobility during pregnancy then a recovery phase in postpartum. Different authors also report an increase of ligamentous laxity (upper and lower limbs) during pregnancy followed by a decrease phase in postpartum. CONCLUSION: Pelvic organ mobility, ligamentous laxity, levator hiatus and urethral mobility change in a similarly way during pregnancy (increase of mobility or distension) and postpartum (recovery). LEVEL OF EVIDENCE: 3.