| Grant number: | 20/11317-9 |
| Support Opportunities: | Regular Research Grants |
| Start date: | April 01, 2021 |
| End date: | June 30, 2022 |
| Field of knowledge: | Health Sciences - Physical Education |
| Principal Investigator: | Paulo Barbosa de Freitas Júnior |
| Grantee: | Paulo Barbosa de Freitas Júnior |
| Host Institution: | Pró-Reitoria de Pós-Graduação e Pesquisa. Universidade Cruzeiro do Sul (UNICSUL). São Paulo , SP, Brazil |
| Associated researchers: | Sandra Maria Sbeghen Ferreira de Freitas |
Abstract
The minimum height of the foot in relation to the ground also known as minimum toe clearance (MTC) that happens in the mid-swing phase is a critical event for success in walking. At that moment, the foot moves forward with a speed 3 times greater than the speed of the center of mass and passes about 2 cm from the ground. The joint angles of the swing and support lower limbs and the pelvis are important for determining the path of the foot and the MTC. Any variation in one of these angles, even a small one, can change the MTC and cause a trip unless one or more of the other angles also change to compensate for the "error" generated by changing one or more angle. It is known that when the central nervous system (CNS) directly controls a specific performance variable (e.g., the horizontal displacement of the CM, foot trajectory in the swing phase), the variability of the elements (e.g., joint/segmental angles) relevant to the control of this salient performance variable is greater than the variability of this performance variable itself (total variability of the elements> variability of the performance variable). The framework of the Uncontrolled Manifold (UCM) hypothesis has been used to test this type of hypothesis. In the case of walking, studies have been done to test some of these hypotheses. For example, it has been observed by several studies that the variability of the mediolateral path of the foot is less than the sum of the total variability of the elements relevant to the task, in this case, the segmental angles. Why is that? It occurs because part of the variability of the elements does not affect the performance variable, which is being controlled. This good variance (VUCM) is important to ensure the flexibility of the system against possible disturbances that may occur during walking (e.g., the appearance of an unexpected obstacle). Another part of the variability of the elements interferes with the performance of the task, increasing the variability of the performance (control) variable. That is the reason it is called bad variance (VORT). In the present project, we will evaluate how the elements (joint angles) vary trial-by-trial to ensure the stability of the MTC in young (<40 years) and older (> 55 years) adults on treadmill walking at different walking speeds. We will measure the good and bad variance and synergy index (V) to confirm that the CNS stabilizes the MTC by directly controlling the angles of the joints relevant to this task. This will be confirmed if VUCM> VORT and V> 0. To achieve this goal, we will use kinematic data on the treadmill already collected and made available in open gait databases. These data have already been checked and are suitable for use in this project. (AU)
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