Movement Symmetry Research Articles

Deep Learning Evidence for Global Optimality of Gerver’s Sofa

The moving sofa problem, introduced by Leo Moser in 1966, seeks to determine the maximal area of a 2D shape that can navigate an L-shaped corridor of unit width. Joseph Gerver’s 1992 solution, providing a lower bound of approximately 2.2195, is the best known, though its global optimality remains unproven. This paper leverages neural networks’ approximation power and recent advances in invexity optimization to explore global optimality. We propose two approaches supporting Gerver’s conjecture that his sofa is the unique global maximum. The first approach uses continuous function learning, discarding assumptions about the monotonicity, symmetry, and differentiability of sofa movements. The sofa area is computed as a differentiable function using our “waterfall” algorithm, with the loss function incorporating both differential terms and initial conditions based on physics-informed machine learning. Extensive training with diverse network initialization consistently converges to Gerver’s solution. The second approach applies discrete optimization to the Kallus–Romik upper bound, improving it from 2.37 to 2.3337 for five rotation angles. As the number of angles increases, our model asymptotically converges to Gerver’s area from above, indicating that no larger sofa exists.

Effect of Programed Walking Exercise Using Bot Fit in Younger Adults

IntroductionPhysical inactivity and sedentary behavior both increase the risk of chronic disease and mortality. Regular participation in physical activity and reducing sedentary behavior play important roles in maintaining physical health and disease prevention.ObjectiveThe purpose of this study was to investigate the effect of programed walking exercise using a wearable hip exoskeleton, Bot Fit on muscle strength, muscle effort, and the kinematics of the pelvis in younger adults.MethodsWe designed three parallel experimental conditions and randomly assigned participants to one of three groups: those assigned to exercise using an interval program of Bot Fit (interval group), those who used a power program of Bot Fit (power group), and a control group who exercised without Bot Fit. A total of 45 young adults participated in 18 exercise-intervention sessions over six weeks, and all participants were assessed at two time points: before and after the 18 exercise sessions. Each assessment evaluated muscle strength, muscle effort, and the kinematics of the pelvis during walking. In addition, the number of steps, distance, energy expenditure, and heart rate for 30 min during the exercise sessions were recorded.ResultsA significant increase in the maximum voluntary contraction (MVC) of the left biceps femoris (BF) was evident in the interval group, while significant changes in the MVC of the bilateral BF were seen in the power group after Bot Fit exercise. A significant decrease of muscle effort in the right BF in the interval group and right lumbar erector spinae and bilateral BF in the power group were also observed. In addition, the symmetry index of pelvic tilt significantly improved in the interval group, and greater exercise volume and intensity in both the interval and power groups compared with the control group were confirmed as measured by the number of steps, distance, energy expenditure, and heart rate.ConclusionsThe results of this study confirmed the beneficial effect of programed walking exercise using the Bot Fit on muscle strength of trunk and lower extremities, muscle effort, and pelvic movement symmetry in younger adults. Personalized exercise programs can be provided for younger adults using various resistance or assistance modes of robotic device with the Bot Fit.Trial RegistrationClinicalTrials.gov, NCT05862077. Registered 22 March 2022, https://register.clinicaltrials.gov/.

Functional Symmetry Observation Scale, Version 2: Reliability, Construct Validity, and Potential for Clinical Use.

To examine the intrarater and interrater reliability and construct validity of the Functional Symmetry Observation Scale, Version 2 (FSOS-V2) in infants with congenital muscular torticollis (CMT). The FSOS-V2 is a video-based measure of postural and movement symmetry in infants with CMT. Four examiners scored 50 participants' videos twice. Scores obtained by the same rater and across 4 raters were compared to examine intrarater and interrater reliability, respectively. Participants' habitual head deviation from midline in supine photographs was measured using a protractor. Relationship between the head tilt angles and FSOS-V2 scores was examined to assess construct validity. Fifty infants with CMT, age range 1 to 16months, participated. Results indicated moderate to good intrarater and poor to moderate interrater reliability. The FSOS-V2 construct validity was supported. The FSOS-V2 can be used by the same therapist repeatedly to make clinical decisions. Further research will strengthen its psychometric properties.

Optimized Tool Motion Symmetry for Strip-Width-Max Mfg of Sculptured Surfaces with Non-Ball Tools Based on Envelope Approximation

Optimized Tool Motion Symmetry for Strip-Width-Max Mfg of Sculptured Surfaces with Non-Ball Tools Based on Envelope Approximation

The Aerodynamic Performance of a Novel Overlapping Octocopter in Hover

A novel octocopter with an overlapping rotor arrangement is proposed in this paper to increase the payload with a limited size. The aerodynamic performance was obtained by both experiments and numerical simulations with the rotor spacing ranging from 1.2 D to 2.0 D (L= 1.2 D, 1.4 D, 1.6 D, 1.8 D, 2.0 D). Also, the aerodynamic parameter was evaluated by the thrust, power consumption, thrust coefficient, power coefficient, and figure of merit (FM) in hover. Compared with a traditional co-axial octocopter, the results indicated that the overlapping octocopter at L= 1.8 D presented an increasing thrust up to 15.98%, and the FM increment was up to 6%. Additionally, the streamline distribution showed that the symmetry of the vortex movement in the downwash flow for the overlapping rotors will offset the rotor interference with an increase in thrust. Meanwhile, the vortex deformation resulting from the induced velocity from the upper rotor also led to an increase in power consumption. Finally, the optimal aerodynamic performance of the overlapping octocopter was obtained with a rotor spacing of L= 1.8 D at 1800 RPM.

What the trained eye cannot see: Quantitative kinematics and machine learning detect movement deficits in early-stage Parkinson's disease from videos

BackgroundEvaluation of disease severity in Parkinson's disease (PD) relies on motor symptoms quantification. However, during early-stage PD, these symptoms are subtle and difficult to quantify by experts, which might result in delayed diagnosis and suboptimal disease management. ObjectiveTo evaluate the use of videos and machine learning (ML) for automatic quantification of motor symptoms in early-stage PD. MethodsWe analyzed videos of three movement tasks—Finger Tapping, Hand Movement, and Leg Agility— from 26 aged-matched healthy controls and 31 early-stage PD patients. Utilizing ML algorithms for pose estimation we extracted kinematic features from these videos and trained three classification models based on left and right-side movements, and right/left symmetry. The models were trained to differentiate healthy controls from early-stage PD from videos. ResultsCombining left side, right side, and symmetry features resulted in a PD detection accuracy of 79 % from Finger Tap videos, 75 % from Hand Movement videos, 79 % from Leg Agility videos, and 86 % when combining the three tasks using a soft voting approach. In contrast, the classification accuracy varied between 40 % and 72 % when the movement side or symmetry were not considered. ConclusionsOur methodology effectively differentiated between early-stage PD and healthy controls using videos of standardized motor tasks by integrating kinematic analyses of left-side, right-side, and bilateral symmetry movements. These results demonstrate that ML can detect movement deficits in early-stage PD from videos. This technology is easy-to-use, highly scalable, and has the potential to improve the management and quantification of motor symptoms in early-stage PD.

Prevalence of movement asymmetries in high-performing riding horses perceived as free from lameness and riders' perception of horse sidedness.

A high proportion of horses in training, perceived as free from lameness by their owner, exhibit vertical movement asymmetries. These types of asymmetries are sensitive measures of lameness, but their specificity as indicators of orthopaedic pathology or locomotor function remains unclear. Equine athletes performing at a high level could be assumed to exhibit a higher degree of movement symmetry compared with the general horse population, but this has not been confirmed. This study investigated the prevalence of movement asymmetries in horses performing at a high level in three equestrian disciplines; show jumping, dressage and eventing, as well as the association between riders' perception of horse sidedness and said movement asymmetries. Using an inertial measurement unit-based system (Equinosis), gait analysis was performed on 123 high-performing horses. The mean difference between the two vertical minimum and between the two maximum values of each stride was recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax). The horses were defined as asymmetric if one or multiple asymmetry parameters exceeded an absolute trial mean of: >6mm for HDmin or HDmax, and >3mm for PDmin or PDmax, with standard deviation less than the respective mean value. Based on the results, 70% of the horses were classified as asymmetric, which is similar to previous findings for young riding horses and horses competing at a lower level. More than one-third of these high-performing horses had asymmetry values of similar magnitude to those seen in clinically lame horses. No clear associations were observed between rider-perceived sidedness and the vertical movement asymmetry values, indicating that the perceived unevenness between sides is not a determinant of vertical movement asymmetry. Longitudinal studies on movement asymmetries in relation to training intensity and full clinical examinations with local or systemic analgesic testing are desired as further research to determine whether these movement asymmetries indicate a welfare problem.

Inertial Sensor-Based Quantification of Movement Symmetry in Trotting Warmblood Show-Jumping Horses after "Limb-by-Limb" Re-Shoeing of Forelimbs with Rolled Rocker Shoes.

Hoof care providers are pivotal for implementing biomechanical optimizations of the musculoskeletal system in the horse. Regular visits allow for the collection of longitudinal, quantitative information ("normal ranges"). Changes in movement symmetry, e.g., after shoeing, are indicative of alterations in weight-bearing and push-off force production. Ten Warmblood show jumping horses (7-13 years; 7 geldings, 3 mares) underwent forelimb re-shoeing with rolled rocker shoes, one limb at a time ("limb-by-limb"). Movement symmetry was measured with inertial sensors attached to the head, withers, and pelvis during straight-line trot and lunging. Normalized differences pre/post re-shoeing were compared to published test-retest repeatability values. Mixed-model analysis with random factors horse and limb within horse and fixed factors surface and exercise direction evaluated movement symmetry changes (p < 0.05, Bonferroni correction). Withers movement indicated increased forelimb push-off with the re-shod limb on the inside of the circle and reduced weight-bearing with the re-shod limb and the ipsilateral hind limb on hard ground compared to soft ground. Movement symmetry measurements indicate that a rolled rocker shoe allows for increased push-off on soft ground in trot in a circle. Similar studies should study different types of shoes for improved practically relevant knowledge about shoeing mechanics, working towards evidence-based preventative shoeing.

Kinematic changes in dairy cows with induced hindlimb lameness: transferring methodology from the field of equine biomechanics

Lameness is a common issue on dairy farms, with serious implications for economy and animal welfare. Affected animals may be overlooked until their condition becomes severe. Thus, improved lameness detection methods are needed. In this study, we describe kinematic changes in dairy cows with induced, mild to moderate hindlimb lameness in detail using a “whole-body approach”. Thereby, we aimed to identify explicable features to discriminate between lame and non-lame animals for use in future automated surveillance systems. For this purpose, we induced a mild to moderate and fully reversible hindlimb lameness in 16 dairy cows. We obtained 41 straight-line walk measurements (containing > 3 000 stride cycles) using 11 inertial measurement units attached to predefined locations on the cows’ upper body and limbs. One baseline and ≥ 1 induction measurement(s) were obtained from each cow. Thirty-one spatial and temporal parameters related to limb movement and inter-limb coordination, upper body vertical displacement symmetry and range of motion (ROMz), as well as pelvic pitch and roll, were calculated on a stride-by-stride basis. For upper body locations, vertical within-stride movement asymmetry was investigated both by calculating within-stride differences between local extrema, and by a signal decomposition approach. For each parameter, the baseline condition was compared with induction condition in linear mixed−effect models, while accounting for stride duration. Significant difference between baseline and induction condition was seen for 23 out of 31 kinematic parameters. Lameness induction was associated with decreased maximum protraction (−5.8%) and retraction (−3.7%) angles of the distal portion of the induced/non-induced limb respectively. Diagonal and lateral dissociation of foot placement (ratio of stride duration) involving the non-induced limb decreased by 8.8 and 4.4%, while diagonal dissociation involving the induced limb increased by 7.7%. Increased within-stride vertical displacement asymmetry of the poll, neck, withers, thoracolumbar junction (back) and tubera sacrale (TS) were seen. This was most notable for the back and poll, where a 40 and 24% increase of the first harmonic amplitude (asymmetric component) and 27 and 14% decrease of the second harmonic amplitude (symmetric component) of vertical displacement were seen. ROMz increased in all these landmarks except for TS. Changes in pelvic roll main components, but not in the range of motion of either pitch or roll angle per stride, were seen. Thus, we identified several kinematic features which may be used in future surveillance systems. Further studies are needed to determine their usefulness in realistic conditions, and to implement methods on farms.

Using microdialysis to monitor dopaminergic support of limb-use control following mesencephalic neurosphere transplantation in a rodent model of Parkinson's Disease

Controlled nigrostriatal dopamine release supports effective limb use during locomotion coordination that becomes compromised after this pathway deteriorates in Parkinson’s Disease (PD). How dopamine release relates to active ongoing behavior control remains unknown. Restoring proper release strategy appears important to successful PD treatment with transplanted dopamine-producing stem cells. This is suggested by apparently distinct behavioral support from tonic or phasic release and corresponding requirements of requisite afferent control exhibited by intact nigrostriatal neurons. Our laboratory previously demonstrated that transplanted dopaminergic cells can elicit skilled movement recovery known to depend on phasic dopamine release. However, efforts to measure this movement-related dopamine release yielded seemingly paradoxical, incongruent results. In response, here we explored whether those previous observations derived from rapid reuptake transport into either transplanted cells or residual, lesion-surviving terminals. We confirmed this using minimal reuptake blockade during intrastriatal microdialysis. After unilateral dopamine depletion, rats received transplants and were subjected to our swimming protocol. Among dopamine-depleted and transplanted rats, treatment supported restoration of limb movement symmetry. Interestingly, subsequent reuptake-restricted microdialysis confirmed distinct swimming-induced dopamine increases clearly occurred among these lesioned/transplanted subjects. Thus, phasic firing control appears to contribute to transplant-derived recovery in Parkinsonian animals.

Examination time-distance characteristics of gait and pelvic kinematics in individuals with Diabetic polyneuropathy: a case-control study

ABSTRACT Background Diabetic Peripheral Neuropathy (DPN) disrupts body and movement biomechanics, increases mechanical stress during walking, and predisposes individuals to injuries owing to the repetitive effects of these stresses. Aims This study aimed to assess and compare the impact of neuropathy on gait and pelvic kinematics in individuals with DPN. Methods This case-control study included two groups: 23 individuals diagnosed with DPN aged between 35–70 and 23 healthy individuals aged–35–70. The BTS-G, a wireless motion sensor, was used to assess the time-distance characteristics of walking in all participants. The system analyzed data pertaining to walking speed, cadence, percentages of stance and swing phases, durations of walking cycles, double-step lengths, pelvic tilt, obliquity, and rotation symmetries. Results There were no statistically significant differences between the groups in cadence, left and right stance phase percentages, or left and right swing phase percentages (p > 0.05). However, significant differences were observed between the groups in terms of speed, left and right walking cycle durations, and left and right double-step lengths (p < 0.05). Additionally, no statistically significant difference was found between the groups in pelvic tilt symmetry and left and right pelvic tilt range of motion values (p > 0.05). Nevertheless, significant differences were identified between the groups in pelvic obliquity symmetry, pelvic rotation symmetry, left and right pelvic obliquity range of motion, and left and right pelvic rotation range of motion values (p < 0.05). Conclusions The findings of this study suggest that individuals with DPN exhibit decreased walking speed, prolonged gait cycle duration, increased double step length, and reduced pelvic obliquity and rotation range of motion.

A protocol to quantify cross-sectional and longitudinal differences in duction patterns.

Currently, there is no established system for quantifying patterns of ocular ductions. This poses challenges in tracking the onset and evolution of ocular motility disorders, as current clinical methodologies rely on subjective observations of individual movements. We propose a protocol that integrates image processing, a statistical framework of summary indices, and criteria for evaluating both cross-sectional and longitudinal differences in ductions to address this methodological gap. We demonstrate that our protocol reliably transforms objective estimates of ocular rotations into normative patterns of total movement area and movement symmetry. This is a critical step towards clinical application in which our protocol could first diagnose and then track the progression and resolution of ocular motility disorders over time.

Upper-Limb Movement Quality before and after Surgery in Women with Breast Cancer: An Exploratory Study.

(1) Background: This study aimed to describe upper-limb (UL) movement quality parameters in women after breast cancer surgery and to explore their clinical relevance in relation to post-surgical pain and disability. (2) Methods: UL movement quality was assessed in 30 women before and 3 weeks after surgery for breast cancer. Via accelerometer data captured from a sensor located at the distal end of the forearm on the operated side, various movement quality parameters (local dynamic stability, movement predictability, movement smoothness, movement symmetry, and movement variability) were investigated while women performed a cyclic, weighted reaching task. At both test moments, the Quick Disabilities of the Arm, Shoulder, and Hand (Quick DASH) questionnaire was filled out to assess UL disability and pain severity. (3) Results: No significant differences in movement quality parameters were found between the pre-surgical and post-surgical time points. No significant correlations between post-operative UL disability or pain severity and movement quality were found. (4) Conclusions: From this study sample, no apparent clinically relevant movement quality parameters could be derived for a cyclic, weighted reaching task. This suggests that the search for an easy-to-use, quantitative analysis tool for UL qualitative functioning to be used in research and clinical practice should continue.

Longitudinal changes in vertical stride regularity, hip flexion, and knee flexion contribute to the alteration in gait speed during hospitalization for stroke

Changes in stride regularity and joint motion during gait appear to be related to improved gait speed in hospitalized patients with stroke. We aimed to clarify the changes in stride regularity and joint motion during gait through longitudinal observations. Furthermore, we aimed to clarify the relationship between changes in gait speed, stride regularity, and joint motion during gait. Seventeen inpatients with stroke were assessed for physical and gait functions at baseline, when they reached functional ambulation category 3, and before discharge. Physical function was assessed using the Fugl-Meyer assessment for the lower extremities and the Berg Balance Scale. Gait function was assessed on the basis of gait speed, joint motion, stride regularity, and step symmetry using inertial sensors. The correlations between the ratio of change in gait speed and each indicator from baseline to discharge were analyzed. Both physical and gait functions improved significantly during the hospital stay. The ratio of change in gait speed was significantly and positively correlated with the ratio of change in vertical stride regularity (r = 0.662), vertical step symmetry (rs = 0.627), hip flexion (rs = 0.652), knee flexion (affected side) (r = 0.611), and ankle plantarflexion (unaffected side) (rs = 0.547). Vertical stride regularity, hip flexion, and knee flexion (affected side) were significant factors in determining the ratio of changes in gait speed. Our results suggest that stride regularity, hip flexion, and knee flexion could explain the entire gait cycle and that of the affected side. These parameters can be used as indices to improve gait speed.

Symmetry and synchrony of bimanual movements are not predicated on interlimb control coupling.

Previous studies suggest that bimanual coordination recruits neural mechanisms that explicitly couple control of the arms, resulting in symmetric kinematics. However, the higher symmetry for actions that require congruous joint motions compared with noncongruous joint motions calls into question the concept of control coupling as a general policy. An alternative view proposes that codependence might emerge from an optimal feedback controller that minimizes control effort and costs in task performance. Support for this view comes from studies comparing conditions in which both hands move a shared or independent virtual objects. Because these studies have mainly focused on congruous bimanual movements, it remains unclear if kinematic symmetry emerges from such control policies. We now examine movements with congruous or noncongruous joint motions (inertially symmetric or asymmetric, respectively) under shared or independent cursors conditions. We reasoned that if a control policy minimizes kinematic differences between limbs, spatiotemporal symmetry should remain relatively unaffected by inertial asymmetries. As shared tasks reportedly elicit greater interlimb codependence, these conditions should elicit higher bilateral covariance regardless of inertial asymmetries. Our results indicate a robust spatiotemporal symmetry only under inertially symmetric conditions, regardless of cursor condition. We simulated bimanual reaching using an optimal feedback controller with and without explicit costs of kinematic asymmetry, finding that only the latter mirrored our empirical data. Our findings support the hypothesis that bimanual control policies do not include kinematic asymmetry as a cost when it is not demanded by task constraints suggesting that kinematic symmetry depends critically on mechanical movement conditions.NEW & NOTEWORTHY Previously, the control coupling hypothesis and task-dependent control hypothesis have been shown to be robust in the bimanually symmetrical movement, but whether the same policy remains robust in the bimanually asymmetrical movement remains unclear. Here, with evidence from empirical and simulation data, we show that a spatiotemporal symmetry between the arms is not predicated on control coupling, but instead it is predicated on the symmetry of mechanical conditions (e.g. limb inertia) between the arms.

Associations between Racing Thoroughbred Movement Asymmetries and Racing and Training Direction.

Racehorses commonly train and race in one direction, which may result in gait asymmetries. This study quantified gait symmetry in two cohorts of Thoroughbreds differing in their predominant exercising direction; we hypothesized that there would be significant differences in the direction of asymmetry between cohorts. 307 Thoroughbreds (156 from Singapore Turf Club (STC)-anticlockwise; 151 from Hong Kong Jockey Club (HKJC)-clockwise) were assessed during a straight-line, in-hand trot on firm ground with inertial sensors on their head and pelvis quantifying differences between the minima, maxima, upward movement amplitudes (MinDiff, MaxDiff, UpDiff), and hip hike (HHD). The presence of asymmetry (≥5 mm) was assessed for each variable. Chi-Squared tests identified differences in the number of horses with left/right-sided movement asymmetry between cohorts and mixed model analyses evaluated differences in the movement symmetry values. HKJC had significantly more left forelimb asymmetrical horses (Head: MinDiff p < 0.0001, MaxDiff p < 0.03, UpDiff p < 0.01) than STC. Pelvis MinDiff (p = 0.010) and UpDiff (p = 0.021), and head MinDiff (p = 0.006) and UpDiff (p = 0.017) values were significantly different between cohorts; HKJC mean values indicated left fore- and hindlimb asymmetry, and STC mean values indicated right fore- and hindlimb asymmetry. the asymmetry differences between cohorts suggest that horses may adapt their gait to their racing direction, with kinematics reflecting reduced 'outside' fore- and hindlimb loading.

Effects of core stability and feedback music on upper body mediolateral movements during cycling

BackgroundAsymmetry in involuntary trunk motion during voluntary movements of the lower extremities is a risk factor for musculoskeletal injuries and may be related to core stability. Core stability plays a pivotal role in maintaining postural stability during distal segment movements. Because mediolateral head motion partially represents trunk motion during rhythmic movements, controlling it can help ensure symmetric trunk motion. This study aimed to investigate the relationship between core stability and asymmetric trunk motion during rhythmic movements, and to evaluate the effects of feedback music on mediolateral head motion.MethodsWe developed a system that uses a wireless earbud and a high-resolution inertial measurement unit sensor to measure head angle and provide feedback music. When the head angle exceeds a predefined threshold, the music is muted in the earbud on the side of the head tilt. In our lab-based study, we measured head angles during cycling at 70% of maximum speed using this self-developed system, and compared them between individuals with good (Sahrmann core stability test: 2–5 level) and poor core stability (0–1 level). The amplitude of mediolateral head motion was represented by the difference between the left and right peak angles, and the symmetry in mediolateral head motion was represented by the average of left and right peak angles.ResultsIndividuals with poor core stability demonstrated significantly greater amplitude of, and less symmetry in, mediolateral head motion than those with good core stability. Additionally, feedback music significantly reduced the amplitude of mediolateral head motion in both the good- and poor-core-stability groups.ConclusionOur findings indicate that core stability is crucial for maintaining symmetric head motion during rhythmic movements like cycling. Feedback music could serve as an effective tool for promoting symmetry in head motion and thus preventing musculoskeletal injuries.

The Equiband Pro System improves gait symmetry in horses at the trot.

Abstract It has been shown that there is a relationship between spinal stability and gait symmetry in horses (1-3). Use of the Equiband Pro System, an elastic band system used for in-hand or ridden work with horses, has previously been shown to improve spinal stability and abdominal muscle engagement (4-6). More recently, it was demonstrated that a 4 week handwalking protocol with the System improves hindlimb symmetry in horses with a mild hind limb lameness (7). The purpose of this study was to determine whether the Equiband Pro System affects gait symmetry immediately in horses trotting on the lunge, using a repeated measures crossover study design. Six horses with varying degrees of gait asymmetries trotted on a lunge in both directions, with and without the abdominal and hindquarter bands of the Equiband Pro System. After evaluation of movement symmetry data, generated by an inertial measurement unit (the Equestic SaddleClip), landing forces were found to be significantly more symmetrical between the left and right diagonal limbs in horses while using the Equiband Pro System (p = 0.05). These results suggest that the Equiband Pro System can immediately alter motor patterns, leading to improved gait symmetry. More work is needed to understand the precise mechanism of this effect.

Physiology and biomechanics researches of the special preparedness and contention activity of highly skilled kayakers

Purpose — development of methodology for individual evaluating special fitness and competitive activity of highly skilled kayakers.&#x0D; The rationality of the rower’s movement structure is largely determined by the character of work and interaction of the posterior and anterior bundles of the deltoid muscle, which perform the rower’s arm movements during applying both “pulling” and “pushing” efforts. The following causes of individual rowing technique errors significantly affecting sports result were identified: general muscle rigidity, lack of sufficiently complete and timely muscle relaxation; untimely involvement of muscles in work (appearance of mutual activity zones of antagonist muscles); late start of muscle activity (inertial moments of movement of rower's body biolinks are not provided before water entrapment); protracted, too long muscle activity (movement is performed entirely at the expense of muscular activity, without the use of inertial and propelling forces); low speed of muscle engagement in work leading, as a rule, to the “drop” of efforts on the oar. Two groups of athletes with diametrically opposite levels of physical capacity development and one group, which was characterized by their uniform development, were distinguished. The first group was distinguished by the high indices of power and efficiency of the work performed while covering the competitive distance. Such athletes showed higher sports results on short distances. The second group was distinguished by high indices of the efficiency of applying efforts, symmetry of movements, and successful performances on long competitive distances. Such rowers were classified as athletes with predominant development of special endurance quality. The rowers of the third group differed in the average values of the above mentioned indices and demonstrated equal success on both short and long competitive distances. Athletes with preferential development of speed-strength qualities and rowers with an advantageous development of special endurance have no significant difference in speed of covering 500 m distance and heart rate. However, there are significant differences in other indices of special fitness. Rowers with even development of physical qualities have differences in all recorded indices compared to those of the first two groups.&#x0D; The individual peculiarities of rowers’ movement coordination during covering a competitive distance of 500 m were determined. All rowers are divided into two groups. The first group is characterized by rational coordination of movements at the beginning of the distance covering and pronounced disturbances in the work dynamics of the muscles of the body turn and the nature of effort applied to the oar at the end of the distance. In the second group, we encounter the opposite phenomenon: with an irrational movement structure at the beginning of the distance, there is a transition of work to a more correct character at the end of its covering. The most preferable option for increasing the efficiency of athletes’ technical preparation is the use of the methodology for designing generalized and individual models of motor action structure. Preparation of rowers with account for their predisposition to the formation of the most important components of sportsmanship is the most preferable option. When drawing up individual plans for the preparation of athletes, the coaches should take into account these practical recommendations and adhere to the recommended directions of training. Repeated examinations (four months later) revealed the effectiveness of managing the process of technical preparation of kayakers based on the correction of intermuscular coordination.

Embodimetrics: A Principal Component Analysis Study of the Combined Assessment of Cardiac, Cognitive and Mobility Parameters.

There is a growing body of literature investigating the relationship between the frequency domain analysis of heart rate variability (HRV) and cognitive Stroop task performance. We proposed a combined assessment integrating trunk mobility in 72 healthy women to investigate the relationship between cognitive, cardiac, and motor variables using principal component analysis (PCA). Additionally, we assessed changes in the relationships among these variables after a two-month intervention aimed at improving the perception-action link. At baseline, PCA correctly identified three components: one related to cardiac variables, one to trunk motion, and one to Stroop task performance. After the intervention, only two components were found, with trunk symmetry and range of motion, accuracy, time to complete the Stroop task, and low-frequency heart rate variability aggregated into a single component using PCA. Artificial neural network analysis confirmed the effects of both HRV and motor behavior on cognitive Stroop task performance. This analysis suggested that this protocol was effective in investigating embodied cognition, and we defined this approach as "embodimetrics".