Brain Activation During Maximum Concentric and Eccentric Knee Extension Muscle Contractions

Purpose: In spite of mounting evidence indicating that concentric and eccentric knee extensor muscle contractions might have special nervous system control strategies, the differentiation of brain frequencies between concentric and eccentric movements and how the motor cortex programs this contraction has been less studied. In this study, the brain and muscle activation differences during maximum concentric and eccentric contractions were compared. Methods: Nine healthy volunteers performed 20 maximum eccentric and 20 maximum concentric knee extensor contractions. Electroencephalography (EEG) signals from sensorimotor-related cortical areas were recorded simultaneous with the electromyography (EMG) of the knee extensor muscles. In the spectral analysis the performance related power values were calculated for Theta (4-7 Hz) and Alpha (7-12 Hz). Results: The time-domain results revealed, longer time and greater cortical activity is required for the preparation of an eccentric contraction. For the eccentric task, the cortical activity was greater, but the EMG was lower in comparison to the concentric task values. Statistical analysis showed significant higher and lower Theta and Alpha power in both types of contractions compared to the resting state, respectively. Conclusion: These findings suggest that increased Theta power is associated with task complexity and focused attention and decreased Alpha power values with increased information processing in the somatosensory cortex

Association between Preparatory Knee Muscle Activation and Knee Valgus Angle during Single Leg Cross Drop Landing Following Anterior Cruciate Ligament Reconstruction

Background: Knee valgus angle seems to be a key factor in both primary– and second–ACL injury risk models. The control of the alignment of the lower limb during dynamic movements depends on the neural activation of the muscles crossing the knee joint prior to the occurrence of stressful events. The current study examined the relationship between the preparatory knee muscle activity and knee valgus angle. Methods: Twenty-eight ACL reconstructed (ACLR) athletes were asked to perform three trials of a single-leg cross drop landing (SCD). Lower extremity kinematics and surface EMG were recorded. Initial contact knee valgus angle and EMG from 100 ms prior to ground contact were used in the data analyses. Results: Preparatory activation medial and lateral hamstring muscles were found to be negatively correlated with knee valgus angle at initial contact (P<0.05). However, the preparatory activity of vastus medialis and vastus lateralis muscles was not associated with initial contact knee valgus angle (P>0.05). Conclusion: The preparatory activity of the knee muscles is linked to knee valgus angle at initial contact, and it may indicate a potential target of second ACL injury prevention programs

Association of Sleep Duration and Quality With Health-Related Quality of Life in Fresher University Students

Background and Objective Sleep duration and quality are important factors for health-related quality of life (HRQoL). This study aimed at investigating the association of sleep duration and quality with HRQoL in fresher students of Neyshabur University of Medical Sciences. Methods The study included 471 fresher students. The sleep duration and sleep quality were measured with the Persian version of Pittsburgh Sleep Quality Index (PSQI) and the HRQoL was evaluated with the Persian version of the 12-Item Short Form Survey (SF-12). The data were collected from late September to early October in 2019 and 2020. The multiple linear regression model was used to determine the independent association of sleep duration and quality with HRQoL. A p-value ≤ 0.05 was considered statistically significant. Results The mean age of the participants was 21.8 ± 6.0 years and the majority of them (62.4%) were female. The total HRQoL score and the prevalence of poor sleep quality were 81.6% and 28.0%, respectively. Among the students, 51.8% and 6.4% reported a sleep duration shorter than 7 hours and equal or more than 9 hours, respectively. The multiple linear regression model showed that excessive sleep duration (≥ 9 h) and sleep quality were associated with Mental Component Summary (MCS) and total HRQoL, respectively (p = 0.036, p = 0.018). Conclusions Referring to the results, enough and quality sleep has beneficial effects on HRQoL in students. Therefore, future strategies should be developed to improve sleep and consequently HRQoL among university students

Age-related changes to motor synergies in multi-joint and multi-finger manipulative skills: a meta-analysis

Purpose The aim of the current meta-analysis was to examine the extent to which there are differences in upper extremity motor synergies across different age groups in manipulative tasks. Methods The studies that used the uncontrolled manifold method to examine the effect of age on motor synergies in multijoint and multi-finger tasks were selected. Sixteen relevant studies from 1154 articles were selected for the meta-analysis—4 and 12 studies considered multi-joint kinematics and multi-finger kinetic tasks respectively. Results The results of the meta-analysis suggested reduced strength of synergies in multi-finger task in older adults, but this was not the case for synergies in multi-joint task. Part of this age-related difference in finger function is related to the increased variability in total force in grasping tasks. However, reductions in the strength of multi-finger synergies in hand functions following ageing appear to depend on the characteristics of the task. Conclusions These findings indicate that the cooperation among fingers to stabilise the total required force to apply for grasping and other fine motor skills is less efficient in older adults that might affect the quality of manipulative tasks

Longitudinal adaptation of vastus lateralis muscle in response to eccentric exercise

In der vorliegenden Studie wurde daher den Einfluss exzentrischen Trainings, mit unterschiedlicher Reizmagnitude, Bewegungsgeschwindigkeit und Muskellänge bei Reizapplikation, auf die Adaptation des M. vastus lateralis (VL) untersucht. Die 31 Studienteilnehmer wurden randomisiert in zwei Trainings- und eine Kontrollgruppe aufgeteilt. Die Trainingsgruppen führten 30 Trainingseinheiten mit exzentrischem Training der Knieextensoren an einem Isokineten durch. Gruppe 1 (n=10) trainierte ein Bein mit 65% der maximalen willkürlichen isometrischen Kontraktion (MVC) und das andere Bein mit 100% MVC, bei einer Winkelgeschwindigkeit von 90°/s und einem Kniewinkel von 25°-100°. Gruppe 2 (n=10) trainierte beide Beine mit 100% MVC, ein Bein aber mit einer Winkelgeschwindigkeit von 90°/s in einem Kniewinkel von 25°-65° und das andere Bein mit 240°/s und 25°-100°. In der Pre- und Postmessung wurde die VL Muskelfaserlänge mittels Ultraschall bestimmt und die Moment-Winkel- und Leistungs-Winkelgeschwindigkeitsrelation mit einem Dynamometer erfasst. Die Ergebnisse zeigen nur für Bein mit 240°/s eine signifikante (pThe present study investigated the effects of magnitude, velocity and muscle length at which the eccentric stimulus is applied on the longitudinal adaptation of the vastus lateralis muscle (VL). The 31 participants were randomly assigned into two experimental groups to perform 30 sessions of eccentric training for the knee extensors (3 times/week) and one control group. The first experimental group (n=10) exercised one leg at 65% of maximum voluntary isometric contraction (MVC) and the second leg at 100% MVC at 90°/s from 25° to 100° knee angle on an isokinetic device (Biodex 3). The second experimental group (n=10) exercised one leg at 100% MVC at 90°/s from 25° to 65° knee angle and the other leg at 100% MVC at an angular velocity of 240°/s from 25° to 100° knee angle. In pre and post measurements the fascicle length of the VL was examined by ultrasonography and the moment-angle and power-angular velocity relationship of the knee extensors with a dynamometer. The results showed an increase (

A new method of diagnosing athlete's anterior cruciate ligament health status using surface electromyography and deep convolutional neural network

International audienc

Corrigendum to “A new method of diagnosing athlete's anterior cruciate ligament health status using surface electromyography and deep convolutional neural network” [Biocybern. Biomed. Eng. 40 (1) (2020) 65–76]

International audienc

The Symmetry Comparison balance Performance and Plantar pressure Distribution in Active Adolescent’s Girls with Ankle Pronation While Standing and Stance Phase of Gait: Symmetry Comparison Balance performance and plantar pressure Distribution in Active adolescent’s female with Ankle Pronation while standing and Stance phase of Gait

Introduction: The foot-ankle ankle has the capability to perform specific functions such as the weight bearing of body in the standing position against the gravity, moving the body to the front and creating stability to keep the balance and control the posture. The purpose of the present study was to evaluate symmetry comparison of balance performance and plantar pressure distribution in active adolescent’s girls with ankle over pronation while standing and during stance phase of gait. Materials and Methods: In this quasi- experimental study, 34 active adolescent girls between 14 and 17 were selected as simple. The navicular drop measurement by Bordy method, the plantar pressure distribution by foot pressure device (PT-Scan4452F100), and the symmetry between the two limbs and balance function by symmetry Index and Balance performance formula were used. Mean and Deviation was used to describe data, Shapiro-Wilk Test to verify the normality od the data, and independent t-test to compare the variable of the two groups at significance level of P≥0.05. Results: The symmetry comparison of balance performance and plantar pressure distribution showed that a significant difference in symmetry of rear foot pressure distribution (P=0.04), symmetry of rear foot impulse (P=0.04), symmetry of medial heel (P=0.04), symmetry of tars 1 (P=0.04) and symmetry of ankle rotation (P=0.03) between two groups, indicating more symmetry in healthy girls than those ankle hyperpronation, indicating more symmetry in healthy girls than those ankle hyperpronation. Conclusion: The current study’s findings showed that the girls with the hyperpronation had less asymmetry on the medial heel foot and increased pressure distribution on the 1st tarsus. Also, the symmetry of balance function of heel rotation around the ankle’s axis and the impulse of rear foot in the healthy group were more than in the hyperpronation group. Furthermore, because of more contact of the inner surface of the soles with the ground in the people with hyperpronation, the pressure level on the inner edge and 1st metatarsus was increased and the medial heel symmetry in the pronation group was decreased compared to the healthy group. Hence, more scientific evidence is needed to generalize the results

C3D data based on 2-dimensional images from video camera

The Human three-dimensional (3D) musculoskeletal model is based on motion analysis methods and can be obtained by particular motion capture systems that export 3D data with coordinate 3D (C3D) format. Unique cameras and specific software are essential for analyzing the data. This equipment is quite expensive, and using them is time-consuming. This research intends to use ordinary video cameras and open source systems to get 3D data and create a C3D format due to these problems. By capturing movements with two video cameras, marker coordination is obtainable using Skill-Spector. To create C3D data from 3D coordinates of the body points, MATLAB functions were used. The subject was captured simultaneously with both the Cortex system and two video cameras during each validation test. The mean correlation coefficient of datasets is 0.7. This method can be used as an alternative method for motion analysis due to a more detailed comparison. The C3D data collection, which we presented in this research, is more accessible and cost-efficient than other systems. In this method, only two cameras have been used

Perceived Discomfort, Neck Kinematics, and Muscular Activity During Smartphone Usage: A Comparative Study

ObjectiveThe present study aims to evaluate the effects of posture, task, and handgrip style on discomfort, neck kinematics, and concomitant muscular activity when using a smartphone (SP).BackgroundAlong with the popularity of smartphones, musculoskeletal disorders have become prevalent among smartphone users. However, comprehensive aspects of discomfort, kinematics, and electromyographic responses across various conditions remain to be investigated.MethodTwenty-four young smartphone users performed typing, video watching, and reading tasks while holding the smartphone both with one hand and with two hands while either sitting or standing. Neck kinematics and muscular activities were simultaneously recorded.ResultsWorking with SPs led to higher discomfort in the neck (p = 0.01), lower back (p = 0.01), and shoulder (p = 0.04) while sitting as compared to standing. Sitting was associated with greater neck flexion and more minor lateral bending for all tasks and grip styles (p \u3c 0.05). Electromyographic analysis indicated significant differences between sitting and standing, with alterations being dependent on the test condition. Moreover, neck kinematics and muscular activities significantly differed based on the task nature, handgrip, and interactions.ConclusionThis study highlights the risk of using smartphones in increased neck angle flexion and muscular activities fatigue. Thus, posture and handgrip should be considered while using SPs. As each test condition affects a specific dependent variable, a holistic approach is required to evaluate the responses of SP users’ musculoskeletal systems.ApplicationResults can be applied to develop guidelines for musculoskeletal disorders/discomfort prevention among SP users, especially with the rise of smartphone use during the COVID-19 pandemic