Synergic control of foot position during stair ascent in young adults

• Grant number: 24/04054-2
• Support Opportunities: Scholarships in Brazil - Master
• Start date: December 01, 2024
• Status: Discontinued
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Paulo Barbosa de Freitas Júnior
• Grantee: Mateus Santos Dias
• Host Institution: Pró-Reitoria de Pós-Graduação e Pesquisa. Universidade Cruzeiro do Sul (UNICSUL). São Paulo , SP, Brazil
• Associated scholarship(s): 25/02453-0 - Multi-Muscle Synergy Preceding Upward and Downward Stepping in Young Adults, BE.EP.MS

Abstract

Ascending a step is a common task, yet it presents challenges in control and execution. The first challenge is to move and place the leading foot (the first to move) onto the step without tripping, while also avoiding excessive energy and time expenditure. The second challenge is to control body movement, represented by the center of mass (CM), in both horizontal and vertical directions, avoiding mediolateral CM oscillations. The third challenge is to move the support foot onto the higher surface after the leading foot makes contact with the step. The focus of this study is on the control of the leading foot and the interaction between motor elements (i.e., joint angles) to achieve the objective of this part of the task. The Uncontrolled Manifold (UCM) analysis has been used to test whether the central nervous system forms motor synergies to stabilize a specific performance variable through the control and coordination of task-relevant motor elements. In this project, we will evaluate whether synergies are formed to coordinate the motor elements (i.e., joint angles) to ensure the stability of the leading foot's position at crucial moments during step ascent. These moments include: 1) the anteroposterior distance between the leading foot and the step when the foot crosses the upper edge of the step; 2) the height of the leading foot when it crosses the front edge of the step; and 3) the maximum height reached by the leading foot during the step ascent. Additionally, we will evaluate the effects of footedness and the reliability of the outcomes calculated using the UCM analysis. To achieve these objectives, we will collect kinematic data from 30 young adults (15 women and 15 men) aged 18 to 40 years. Kinematic data from reflective markers placed on specific body locations will be used to calculate the linear displacements of the foot and angular displacements of segments and joints, respectively. From these data, we will calculate the synergy index (¿V) using the UCM analytical technique and other key outcomes to describe behavior.