BIOMECHANICAL FEATURES OF PERFORMANCE DOMINANCE IN THE LOWER LIMBS

INTRODUCTION: The kinematic, dynamic and myoelectrical characteristics of the one-foot vertical jump were examined for the dominant and the non-dominant foot, in order to determine the biomechanical features of performance dominance in the lower limbs. METHODS: Seventy-nine volunteers performed five vertical jumps with either foot on a piezoelectric force platform (Kistler). The sampling frequency was set at 1000 Hz. Three-dimensional analysis was employed for the determination of the kinematic characteristics of the movement, at a sampling rate of 60 Hz. The APAS system was used to record surface electromyograms of four muscles in the lower limb (sampling frequency 1000 Hz). The foot that achieved the highest performance was defined as the dominant foot. Correspondence analysis was employed for the evaluation of the data. RESULTS: The analysis of the data revealed that high performance scores were the output of a common movement pattern for both the dominant and the nondominant foot. Small values of the maximum angular velocity of the foot, leg and thigh were found during the supporting phase of the jump with either limb. The biceps femoris was highly activated before the contact of the foot, but presented less activity during the supporting phase of the jump. The activity of the biceps femoris before the supporting phase of the jump was greater when the jump was performed with the dominant foot. The vastus medialis of the dominant limb presented greater activity during the negative phase of the jump. Finally, the rectus femoris presented greater activity during the positive phase of the jump when the jump was executed with the dominant foot, while the activity of the gastrocnemius was less. CONCLUSION: The differences of the myoelectrical activity of the biceps femoris between the dominant and the non-dominant foot werprimarily responsible for the differences between the two feet in the height of the jump

BIOMECHANICAL ANALYSIS OF PERFORMANCE IMPROVEMENT IN AIMING MOTOR TASKS

INTRODUCTION: The improvement of performance is closely related to specific modifications of the kinematics and the myoelectrical parameters of each aiming motor skill. The purpose of this study was to determine the modifications of selected kinematic and myoelectrical parameters which resulted in the improvement of aiming performance. METHODS: Seventy volunteers practiced a novel throwing skill which involved the throw of a ball performing elbow flexion. Kinematics were computed through film analysis at 80Hz. Furthermore, the surface ectromyograms of four muscles in the elbow region were analyzed to determine the changes in the timing and the intensity of muscle activation which may be accounted for improved performance. The correspondence analysis was employed for the evaluation of the data. RESULTS: The results revealed that performance enhancement was related to the decrease in the time and the displacement of the movement. Practice also resulted to significant modifications in the electrical activity of the muscles. The number of the active muscles was diminished and the agonist activity was reduced. The antagonist activity was increased but it was presented significantly farther from the beginning of the movement after practice. CONCLUSION: Practice brought about specific modifications in the muscular contribution to the throwing task, by means of a reduction in the electrical activity of the primary antagonistic muscles during the movement. These modifications gave rise to specific alterations in the physical aspects of the skill, which directly resulted in improved performance

Volleyball coaches behavior assessment through systematic observation

The purpose of this study was to record and evaluate the practice behaviors of 12 Greek Volleyball National Division coaches, mean age 47.36 (SD=6.1) through feedback that they provided to their athletes throughout the 2010-11 seasons. Verbal and non verbal behaviors were video recorded during four practices, of each coach. A total of 13.400 behaviors were observed and were coded using the Revised Coaching Behavior Recording Form which corresponded to the 12 categories of the instrument. The analyses of videotaped behaviors were made by two trained observers who were checked in the internal and external reliability. Results indicated that there were 279.11 coded coaching behaviors in each training session. A large proportion of reported coaching behaviors 17.38% (n=48.34) were about "Tactical Instruction", followed by "General Instruction" 15.92% (n=44.45) and "Technical Instruction" 12.42% (n=34.68). "Encouragement" and "Motivation" were 10.76% and 10.73% respectively. "Other Comments" (8.67%) and "Demonstration" (8.26%) were in lower rate. ANOVA revealed that there were not differences between 1st and 2nd division coaching behavior, instead of "Criticism" (p < 0.05) with 2nd division coaches have more comments and "Non verbal reward" (p < 0.05) which 1st division coaches were used more often

Gait analysis comparison between manual marking, 2D pose estimation algorithms, and 3D marker-based system

IntroductionRecent advances in Artificial Intelligence (AI) and Computer Vision (CV) have led to automated pose estimation algorithms using simple 2D videos. This has created the potential to perform kinematic measurements without the need for specialized, and often expensive, equipment. Even though there's a growing body of literature on the development and validation of such algorithms for practical use, they haven't been adopted by health professionals. As a result, manual video annotation tools remain pretty common. Part of the reason is that the pose estimation modules can be erratic, producing errors that are difficult to rectify. Because of that, health professionals prefer the use of tried and true methods despite the time and cost savings pose estimation can offer.MethodsIn this work, the gait cycle of a sample of the elderly population on a split-belt treadmill is examined. The Openpose (OP) and Mediapipe (MP) AI pose estimation algorithms are compared to joint kinematics from a marker-based 3D motion capture system (Vicon), as well as from a video annotation tool designed for biomechanics (Kinovea). Bland-Altman (B-A) graphs and Statistical Parametric Mapping (SPM) are used to identify regions of statistically significant difference.ResultsResults showed that pose estimation can achieve motion tracking comparable to marker-based systems but struggle to identify joints that exhibit small, but crucial motion.DiscussionJoints such as the ankle, can suffer from misidentification of their anatomical landmarks. Manual tools don't have that problem, but the user will introduce a static offset across the measurements. It is proposed that an AI-powered video annotation tool that allows the user to correct errors would bring the benefits of pose estimation to professionals at a low cost

Whole Grain Products, Fish and Bilberries Alter Glucose and Lipid Metabolism in a Randomized, Controlled Trial: The Sysdimet Study

Due to the growing prevalence of type 2 diabetes, new dietary solutions are needed to help improve glucose and lipid metabolism in persons at high risk of developing the disease. Herein we investigated the effects of low-insulin-response grain products, fatty fish, and berries on glucose metabolism and plasma lipidomic profiles in persons with impaired glucose metabolism.Altogether 106 men and women with impaired glucose metabolism and with at least two other features of the metabolic syndrome were included in a 12-week parallel dietary intervention. The participants were randomized into three diet intervention groups: (1) whole grain and low postprandial insulin response grain products, fatty fish three times a week, and bilberries three portions per day (HealthyDiet group), (2) Whole grain enriched diet (WGED) group, which includes principally the same grain products as group (1), but with no change in fish or berry consumption, and (3) refined wheat breads (Control). Oral glucose tolerance, plasma fatty acids and lipidomic profiles were measured before and after the intervention. Self-reported compliance with the diets was good and the body weight remained constant. Within the HealthyDiet group two hour glucose concentration and area-under-the-curve for glucose decreased and plasma proportion of (n-3) long-chain PUFAs increased (False Discovery Rate p-values <0.05). Increases in eicosapentaenoic acid and docosahexaenoic acid associated curvilinearly with the improved insulin secretion and glucose disposal. Among the 364 characterized lipids, 25 changed significantly in the HealthyDiet group, including multiple triglycerides incorporating the long chain (n-3) PUFA.The results suggest that the diet rich in whole grain and low insulin response grain products, bilberries, and fatty fish improve glucose metabolism and alter the lipidomic profile. Therefore, such a diet may have a beneficial effect in the efforts to prevent type 2 diabetes in high risk persons.ClinicalTrials.gov NCT00573781

A Comparative Analysis of Symmetry Indices for Spatiotemporal Gait Features in Early Parkinson’s Disease

This study compared the five most commonly used equations for calculating gait symmetry in discrete variables among Parkinson’s disease patients. Twelve patients (five women and seven men) performed ten consecutive gait trials on a 10 m walkway. Gait data were collected using eight optoelectronic cameras (100 fr/s). The analysis focused on various spatiotemporal parameters, including cadence, step time, stride time, single support, double support, walking speed, step length, stride length, step width, and foot angle. Five symmetry indices were calculated for each trial rather than averaging the ten recorded trials. The variability in and reliability of each symmetry equation were assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC), respectively. Additionally, Bland–Altman plots were produced to visualize the agreement between each pair of methods for each spatiotemporal parameter. The results revealed that the symmetry ratio method exhibited lower variability and higher reliability compared with the other four indices across all spatiotemporal gait parameters. However, it was found that the reliability of a single trial was generally poor, regardless of the symmetry calculation formula used. Therefore, we recommend basing measurements of gait asymmetry in Parkinson’s disease on multiple trials

The Effect of an Interventional Movement Program on the Mechanical Gait Characteristics of a Patient with Dementia

We investigated the effect of an occupational therapy movement program (OTMP) on the specific mechanical characteristics of walking in a person with dementia. The hip joint of the patient’s dominant limb was examined for flexion, extension, adduction, abduction, and internal or external rotation movements. This study included simple gait and dual-task gait conditions, with motor and cognitive tasks performed simultaneously. Neuropsychological scales and the gait analysis system (Vicon) were used to assess the patient pre- and post-intervention. Following the OTMP, statistically significant improvements were observed in hip movements, including flexion/extension, adduction/abduction, and internal/external rotation. These findings suggest that the OTMP can enhance hip mechanical gait characteristics and potentially contribute to functional independence in individuals with dementia