Studying movement reorganization when learning a whole-body action: Example of learning a constrained gait pattern

In order to better understand the process of learning a complex motor skill, an effort was done to identify principles of movement reorganization. However, many studies refuted the existence of generalized invariant “strategies” for mastering the redundant degrees of freedom and emphasized the importance of the constraints especially those linked to the task itself. We aimed to identify common characteristics in movement reorganization when 7 participants practiced (4 sessions) a new gait pattern at speeds higher than that of the preferred walk-to-run transition by placing biomechanical constraints on distal lower joints (i.e. racewalking regulations). Movement analysis was performed on kinematic variables computed from a whole-body model (VICON). First, using ANOVAs we assessed practice-related changes in spatiotemporal parameters, angular displacements and relative phases (inter-/intra-limb coordination). Results indicated an immediate reorganization incoordinative patterns (e.g., relative phases and stride frequency) accompanied by a general decrease in the initial movement variability (i.e., standard deviation of many key variables). However, the large number of studied variables made it difficult to put forward common “strategies” used by participants. Second, we ran principal component analyses (PCA) on 8 major angular displacement variables for all participants, trials and sessions. PCA were used to evaluate the coupling in the motion of body segments that synchronize in different components (dimensions), each believed to be controlled by the CNS as one unit. Results indicated that the majority of participants immediately recruited an additional task-specific control dimension compared to normal walking. Moreover, this analysis revealed a gradual synchronization of the knee joint motion with that of the early established pelvis transverse plane rotation

Adaptive Effects of Seeing Green Environment on Psychophysiological Parameters When Walking or Running

Several studies have investigated the influence of perceiving colors on affective outcomes and/or performance. However, the effects of seeing colors on self-selected behaviors have received little attention from physiologists and psychologists. Therefore, the present study aimed at examining whether exposure to green and red environments could influence affective judgments, perception of effort, heart rate, and gait speeds when walking and running at a self-selected pace. Participants were randomly assigned to one of the three experimental conditions: Green, red, or white (neutral) environment. The experimental task consisted in a 20-min trial of either walking (Study 1) or running (Study 2) at the most comfortable speed on a treadmill surrounded by three large HD TV screens displaying specific properties of the studied colors. Study 1 revealed that walking in a green environment induced a significant reduction in heart rate values as compared to the red and white conditions although no differences in gait speed were found. This corroborates the calming and relaxing effect of green on the human organism. Study 2 showed that running in a green environment was associated with an increased level of perceived exertion at similar speeds (compared to other color conditions), while exposure to red induced a significant decrease in the level of tension. In both studies, the preferred gait speed was not affected by the colored environment which is discussed in relation to the energy-conservation principle. Furthermore, both studies showed that performing a 20-min walk or run at preferred pace presented beneficial mood changes. Implications of the effects of self-selected exercise under colored environments on human functioning are addressed in the discussion

Réorganisation du mouvement avec l'apprentissage d'une habileté motrice complexe, la marche athlétique (rôle de l'énergie métabolique et de la perception de l'effort. Effet de cet apprentissage sur les transitions marche-course)

Ce travail avait pour premier objectif d analyser la réorganisation du mouvement lors de l apprentissage d une habileté motrice complexe, la marche athlétique. Le deuxième objectif était de mieux comprendre le rôle des facteurs métaboliques et de la perception de l effort sur ce processus.Pour cela, les deux premières études se sont intéressées à l évolution d un grand nombre de variables cinématiques avec la pratique. Les participants ont reçu au début de chaque séance de pratique trois consignes (i.e., contraintes biomécaniques) concernant la règlementation et la technique de la marche athlétique. Les résultats de l étude 1 ont mis en évidence une évolution rapide de la coordination et du contrôle (Newell, 1985) qui semble atteindre un plateau à la quatrième séance de pratique sur les sept réalisées. L étude 2, qui analyse d une façon plus approfondie ces quatre premières séances, a indiqué un rôle important des contraintes de la tâche sur la réorganisation du mouvement avec la pratique,réfutant l existence de principes généraux concernant la maîtrise des degrés de liberté (Bernstein,1967). De plus, l étude 1 a montré une réduction des valeurs métaboliques et de la perception de l effort périphérique lors de la pratique, qui corrèlent significativement avec la réorganisation globale du mouvement. Les résultats semblent indiquer un rôle important des informations sensorielles périphériques sur l adoption de patterns de mouvements plus économiques avec la pratique. L étude 3a montré que suite aux 7 séances d apprentissage, les participants adoptent spontanément au test de transition un nouveau comportement, la marche athlétique, entre la marche et la course, et ce pour des raisons non-métaboliques. En conclusion, ce travail propose que la réorganisation du mouvement lors de l apprentissage de la marche athlétique soit orientée par les contraintes de la tâche d une part et parla perception de l effort périphérique d autre part dans un but d optimisation métabolique. Toutefois,l optimisation des facteurs métabolique ne semble pas prioritaire lorsque le système locomoteur doit s adapter rapidement face à un niveau critique de contrainte.The first aim of the present work was to investigate movement reorganization with learning a complex motor skill, racewalking. The second aim was to bring more insight into the role of metabolic factors and perceived exertion. To do so, the first two studies analyzed the evolution of a large number of kinematic variables when participants underwent the practice sessions. At the start of each session, three instructions (i.e., biomechanical constraints) concerning the regulations and technique of racewalking were given. The results of the first study put forward a rapid evolution ofcoordination and control (Newell, 1985) that seem to reach a plateau at the fourth session out of seven in total. The second study, that investigated closely these first four sessions, revealed an important role of task constraints on movement reorganization, refuting the existence of general principles concerning the mastery of degrees of freedom (Bernstein, 1967). Furthermore, the first study showed a reduction in metabolic values and peripheral perceived exertion with practice, which were significantly correlated to the global movement reorganization. Overall, the results seem to raise an important role of peripheral sensory information on the adoption of more economical movement patterns with practice. The third study showed that after the seven learning session, participants spontaneously adopted racewalking as a new pattern in the transition test, between walking and running, for non-metabolic reasons. In conclusion, the present work proposes that the movement reorganization accompanying the learning of racewalking is oriented by task constraints on one sideand peripheral perceived exertion on the other aiming for metabolic optimization. Nevertheless, optimization of metabolic factors doesn t seem a priority when the motor system should quickly adapt to a critical level of constraints.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

A Prototype Of Virtually Interactive Hand Activating Devise-Low Cost Portable Head Mounted System (vihad Plus) For Neurological Rehabilitation

Background and Purpose: Restoring function in individuals who have severe paralysis of the upper extremity secondary to stroke is challenging. Recent technologies have made it possible to use robotic devices as novel tools for assisting the therapists to provide safe and intensive rehabilitation with repeated motions. However, most of the training robots are types of Continuous Passive Motion (CPM) devices that produce slower and stereotyped movement patterns. Earlier works have shown that passive or slow movements do not significantly benefit motor improvement. Several studies reveal that even the use of ipsilateral electromyographic (EMG) pattern recognition approaches might not be practical to decode movement intention and, may negatively affect re-mapping of the neural pathways in the brain. To have a successful hand rehabilitation system, the system should be able to produce a wide variety of unpredicted and challenging movement patterns of various degrees of speed and range of motion with increasing complexity, sufficient enough to produce the necessary neurological plasticity of the affected brain. Current rehabilitation devices are not sufficient to produce such a range of complex activities which enables maximum neurological plasticity. Objective: In this work, we describe a prototype of the contralateral EMG-based Interactive Hand Activating Devise for Stroke (IHADS) system that can detect a hemiplegic person's intention for bilaterally executed hand activities using his/her surface EMG signals from the non-affected side (contralateral). Furthermore, this system can assist in bilateral hand activities through an exoskeleton attached to the hemiplegic upper extremity to initiate progressively challenging and unpredicted type of activities in a virtual reality (VR) world to obtain optimum functional recovery by inducing maximum neurological plasticity. Design: The IHADS system is made up of an embedded controller and a robotic exoskeleton, contralateral EMG sensors and a VR interface with a semi-immersed VR system, where the patient will be seeing progressively impulsive activities that would force the brain to activate the affected extremity to manipulate through the remaining neural networks and mirror neuronal system which in turn will optimize the neurological recovery. This means that the paralyzed arm will be following the motion of the healthy arm whose motion is picked up by the EMG sensors and are translated as actuation signals for the exoskeleton to execute virtually created challenging activities. Conclusion: Contralateral EMG-based 'IHADS' system is a unique, cost effective, highly innovative and portable robotic device. If incorporated into the stroke rehabilitation, this system will be capable of autonomous guidance through the use of real-time feedback from the contralateral upper limb, integrated via the VR interface and the hand activating device to make rehabilitation more intense, functional, motivating, and capable of inducing maximum neurological plasticity

Analysis of the relationship between physical self-concept and body composition

Introduction: Body image is a psychological construct which refers to self-concept including self-image and feelings an individual perceives regarding his or her body. Several studies have examined how women subjectively perceive their bodies in Western cultures compared to objective measures. However, limited studies have examined this relationship among women in the Gulf region (e.g., Qatar) in which Islamic traditional clothing (i.e., Abaya) is typically adopted and possible differences in the judgment of a healthy body shape might be found. The purpose of this study was to see whether there is a connection between the objective body composition measures [i.e., body weight (BW), body height (BH), body mass index (BMI)] and the subjective measures of physical self-description. We expect to find a tendency among females in this study to estimate a thinner body image compared to their current/measured one. Methods: 97 female volunteers (18-26 years) were recruited from Qatar University. We measured their body composition (i.e., BW, BH and BMI). We used the short version of the Physical Self-Description Questionnaire (PSDQ), a multidimensional physical self-concept instrument with 11 original subscales including: body fat, health, appearance, global physical self-concept. The collected data for all variables were analyzed using Statistica software (v.12, DELL) for correlations using Pearson’s coefficients. Results: Based on the BMI results, 25.7% of the participants were classified as overweight or obese (12.3% and 13.4%, respectively). Results indicated a significant negative moderate correlation between the global physical self-concept on one side and BMI (r=-0.27) and BW (r=-2.0) on the other. Furthermore, the perceived body fat showed significant negative correlation with BMI (r=-0.57) and with BW (r=-0.52). The inter-correlation within the subscales showed that the perceived body fat was significantly correlated with appearance (r=0.25), health (r=0.16) and global physical score (r=0.34). Conclusion: Our results indicated a clear and logic relationship between perceived global physical self-concept scores and participants` body composition (i.e., negative correlation). However, an interesting result in line with our hypothesis and concerning the way participants perceived their own body fat indicates a negatively correlation with BMI and BW. In the studied population, a possible interpretation could be done based on the positive link revealed between perceived body fat, perceived appearance, perceived health and global physical score. Indeed, this could indicate that the ideal perceived body might be different and higher than norms presented in the World Health Organization classification. To get further insights on the nature of these relationships, we have started new investigations on the relationship between the other subscales of physical self-description and a comprehensive physical fitness test (ALPHA-FIT Test, UK).This publication was made possible by UREP grant #17-044-3-011 from the Qatar national research fund (a member of Qatar foundation). The statements made herein are solely the responsibility of the authors

Muscle Strength and Glycaemic Control among Patients with Type 2 Diabetes.

Poor glycaemic control is associated with chronic life-threatening complications. This cross-sectional study examined whether there is an association between handgrip strength and glycaemic control among patients with diabetes. Data on 1058 participants aged 40 and older were collected from the National Health and Nutritional Examination Survey (NHANES). Muscle strength was assessed using a handgrip dynamometer, and glycaemic control was assessed using HbA1c. Handgrip strength was presented as age- and gender-specific quartiles, with participants in quartile 1 having the lowest handgrip strength and participants in quartile 4 having the highest handgrip strength. Logistic regression analyses were used to assess the association between handgrip strength and poor glycaemic control among participants with diabetes. Three models, each adjusted to include different variables, were employed. Odds ratio (OR) values revealed no association between handgrip strength and glycaemic control after adjusting for age, gender, and race in model 1. With further adjustment for sedentary activity, income-to-poverty ratio, education, and smoking, patients in quartile 4 of handgrip strength had 0.51 odds of poor glycaemic control (95% CI: 0.27-0.99). However, the reported association above vanished when further adjusted for insulin use (OR = 0.67; 95% CI: 0.35-1.28). In conclusion, findings may indicate an association between glycaemic control and muscle strength. This association may be altered by insulin use; further investigations are required.Qatar University (project No. QUST-1-CHS-2020-11

Physical fitness and physical self-concept of male and female young adults in Qatar

Background Physical inactivity is high within the Qatari population, particularly within females, and school-based environments, contributing to increased morbidity and mortality. School-based physical activity (PA) outcomes may be mediated by physical self-concept. Low physical self-concept may negatively impact PA engagement, compromising childhood and adolescent physical fitness, which may translate into adulthood. Normative physical fitness data for the Qatari population is unavailable. Stratifying normative physical fitness appears prudent, to not only allow comparisons to be made worldwide, but enable informed decisions for public health policy and future interventions in the Qatari population.Scopu

Characteristics of preferred walking patterns in young Qatari adults

Walking is the most natural and important activity of daily living as it refers to the primary type of terrestrial human locomotion. Analyses of gait patterns typically examine the speed and manner in which people prefer to walk. Even though humans can walk at speeds ranging from near 0 km/h to 9 km/h, they typically only use a very limited range of speeds around 4.5 km/h in their daily life (Bohannon & Andrews, 2011). The preferred walking speed (PWS) is used in clinical settings as an indicator of a person’s mobility. For example, elderly people, or those suffering from osteoarthritis prefer to walk at slower speeds. Therefore, improving their PWS is considered as a significant clinical goal. Many studies on gait analysis tried to identify the basic parameters of normal unconstrained gait in different populations. Despite the fundamental common shared characteristics, walking patterns may vary from a person to another according to several factors such as age, gender, physical characteristics, etc. In a study examining the “pace” of random pedestrians in 31 cities around the world, differences in the walking speed were found to be linked to parameters such as climate, economic variables, size of population and cities (Levine & Norenzayan, 1999). More recently, a study has put forward the impact of the cultural background on walking norms by revealing several significant differences in basic gait parameters between young Kuwaiti and Swedish adults (Al-Obaidi et al., 2003). Specifically, the authors presented the first evidence concerning walking patterns in a population from the Gulf region and proposed an interpretation to the found differences that is linked to traditional clothing and foot wear. This reveals the need for a specific normative database targeting healthy young Qataris. Creating such databases for Qatar is desirable for rehabilitation purposes for people with impaired walking patterns (e.g., elderly fallers, people suffering from stroke consequences, hemiplegia, Parkinson disease, etc). For instance, the aim of this study is to evaluate the preferred walking speed and manners in which young male and female Qatari adults walk as compared to non-Qatari participants with similar physical characteristics. To characterize walking patterns we used spatiotemporal kinematic indicators such as stride length, stride frequency and support phase duration. The associated physiological cost and perceived exertion of walking at a preferred pace will also be examined to test for possible differences. We expect to see differences between the preferred walking patterns of Qatari and non-Qatari participants as proposed by Al-Obaidi and collaborators (2003)

Ketamine-based sedation use in mechanically ventilated critically ill patients with COVID-19: A multicenter cohort study

Backgrounds: Ketamine possesses analgesia, anti-inflammation, anticonvulsant, and neuroprotection properties. However, the evidence that supports its use in mechanically ventilated critically ill patients with COVID-19 is insufficient. The study's goal was to assess ketamine's effectiveness and safety in critically ill, mechanically ventilated (MV) patients with COVID-19. Methods: Adult critically ill patients with COVID-19 were included in a multicenter retrospective-prospective cohort study. Patients admitted between March 1, 2020, and July 31, 2021, to five ICUs in Saudi Arabia were included. Eligible patients who required MV within 24 hours of ICU admission were divided into two sub-cohort groups based on their use of ketamine (Control vs. Ketamine). The primary outcome was the length of stay (LOS) in the hospital. P/F ratio differences, lactic acid normalization, MV duration, and mortality were considered secondary outcomes. Propensity score (PS) matching was used (1:2 ratio) based on the selected criteria. Results: In total, 1,130 patients met the eligibility criteria. Among these, 1036 patients (91.7 %) were in the control group, whereas 94 patients (8.3 %) received ketamine. The total number of patients after PS matching, was 264 patients, including 88 patients (33.3 %) who received ketamine. The ketamine group's LOS was significantly lower (beta coefficient (95 % CI): −0.26 (−0.45, −0.07), P = 0.008). Furthermore, the PaO2/FiO2 ratio significantly improved 24 hours after the start of ketamine treatment compared to the pre-treatment period (6 hours) (124.9 (92.1, 184.5) vs. 106 (73.1, 129.3; P = 0.002). Additionally, the ketamine group had a substantially shorter mean time for lactic acid normalization (beta coefficient (95 % CI): −1.55 (−2.42, −0.69), P 0.01). However, there were no significant differences in the duration of MV or mortality. Conclusions: Ketamine-based sedation was associated with lower hospital LOS and faster lactic acid normalization but no mortality benefits in critically ill patients with COVID-19. Thus, larger prospective studies are recommended to assess the safety and effectiveness of ketamine as a sedative in critically ill adult patients