Body Center Of Gravity Research Articles

Kinematic differences between female national and provincial athletes in the tennis serve.

Tennis, the second-largest ball game in the world, has a particularly wide audience. To date, little research has been conducted on the biomechanics of female serves. The purpose of this study was to capture the key moments by using 1,000 frames/s high-speed video analysis, to analyze the kinematics of the serving techniques of national athletes and provincial athletes, to determine the differences between the two levels of athletes, and to provide theoretical references for the improvement of scientific training level. Ten female athletes were selected as participants for this study, five of whom are national athletes, and the other are provincial athletes. Three-dimensional filming techniques were employed to capture videos of the first and second serve techniques. Simi Motion was applied to obtain the 3D kinematic data. Statistical analyses were performed using IBM SPSS Statistics 27.0, and Mann-Whitney U tests were conducted to determine differences between groups. Significant differences in kinematics were found between national and provincial athletes. At the moment of the left knee's minimum flexion (T2), in the first serve, national athletes had a smaller shoulder-hip vertical plane angle (-18.281 ± 6.142° vs. -25.631 ± 3.497°; p = 0.047) and a larger hip vertical plane rotation angle (-9.378 ± 4.263° vs. -0.470 ± 4.724°; p = 0.047). In the second serve, national athletes had a smaller hip horizontal plane rotation angle (-1.720 ± 4.683° vs. 24.146 ± 24.014°; p = 0.047) but a larger hip vertical plane rotation angle (-11.553 ± 1.949° vs. -0.422 ± 4.958°; p = 0.009). At the moment of impact (T4), in the second serve, national athletes' batting position (0.296 ± 0.088 m vs. 0.446 ± 0.094 m; p = 0.047) was further back. Additionally, in the second serve, national athletes consistently had their body center of gravity further back at T2 (-0.106 ± 0.052 m vs. -0.018 ± 0.048 m; p = 0.028), T3 (0.002 ± 0.038 m vs. 0.132 ± 0.039 m; p = 0.009), and T4 (0.073 ± 0.050 m vs. 0.217 ± 0.034 m; p = 0.009). The results of this study indicated several significant kinematic differences between national and provincial athletes, these variations were noted in the shoulder, hip, and body center of gravity. In summary, for the overall first and second serves, it is recommended that national athletes increase the horizontal plane angle of the shoulders and hips at T2, whereas provincial athletes decrease the horizontal plane angle of the shoulder-hip. In addition, provincial athletes need to increase the vertical plane angle of the hip joint, so that the top of the hip can be increased more, and provincial athletes need to be careful not to have the center of gravity too far in front of the body at T2, T3, and T4, so that it can hit the ball at a higher position to increase the swing speed.

Effect of slope change on kinematics of amateur golfers' full swing.

Golf courses are designed with uneven terrain. These factors are especially important when facing (slope), players need to straighten the posture of each part of the body in order to complete the swing on an inclined surface such as flat ground. Amateur players may be more likely to change the movement patterns of their shots due to uneven terrain. Therefore, it may be necessary to clarify the shot characteristics of amateur players and provide reference materials for technical improvement. The purpose of this study was to examine the effect of slope on amateur golfers' swing kinematics by analyzing the variation of time variables, body center of gravity (COG), and shot parameters of amateur golfers' swing at different ground slopes. Six male amateur golfers participated in the experiment. The 7-iron was used for 5 swings each at three slopes: flat ground (FG, 0∘), ball below foot (BBF, +10∘), and foot below ball (FBB, -10∘). The OptiTrack-Motion capture system was used to collect kinematic data, and the three-dimensional motion data will be transmitted to Visual3D software for subsequent data analysis such as golf swing division and body COG changes. Shot parameters (carry, swing speed, ball speed, and smash factor) were recorded for each swing using the Caddie SC300 radar monitoring device. The results showed that there was no difference in the overall swing time and the time required for each interval at different slopes (p> 0.05) there is no significant difference in the change of the COG of the body in the forward and backward directions (p> 0.05). The three slopes of swing speed, ball speed, carry and smash factor were not significantly different (p> 0.05). The rhythm of the amateur golfer's swing was not affected by the slope, but the slope restricts the movement of the body's COG, which may affect the weight movement, and ultimately cause the performance parameters to not reach the level of the FG.

Screening testing and computerized vestibulometry in vestibular neuronitis

Introduction. The demonstrative example of unilateral peripheral vestibulopathy is vestibular neuronitis. This disease of infectious-toxic origin has the involvement of vestibular ganglia neurons or vestibular nerve fibers. The overwhelming moment in topic diagnostics of vestibular impairments is within-patient comparison anamnesis data and vestibulometry results. In cases of vestibular neuronitis exception of central vestibular system pathology is mandatory. Objective. To attain objectification of disequilibrium in vestibular neuronitis by means of registration and assessment of oculogyric and postural reactions. Materials and methods. Vestibular passport trials are recommended in the examination of patients with acute vertiginous complaints. Special attention has been given to the revelation of impairments of command eye movements, disturbances of ocular pursuit, spontaneous nystagmus, and catch-up saccades in Halmagyi – Curthoys test. Possible impairments of static and dynamic balance control are assessed in modified Romberg test and Unterberger test. Gaze tests with registration of saccadic and pursuit eye movements, spontaneous and optokinetic nystagmus reactions as well bithermal caloric test are carried out in computerized electrooculography and videooculography. Deviations of body gravity center are analyzed with the help of sensory organization test in computerized dynamic posturography. Results and discussion. The results of screening and computerized vestibular testing of 24 patients are presented. High diagnostic value of registration and analysis of oculogyric reactions as well as postural control signs is demonstrated in cases of acute vestibular neuronitis and acerbation of its chronic recurrent variant. The key objective symptom, which confirms peripheral level of vestibular dysfunction, is spontaneous nystagmus registration in elimination of gaze fixation. Unsteadiness in static and dynamic trials confirms the vestibular decompensation extent in acute phase of vestibular ganglia / neurons pathology in cases of vestibular neuronitis. Decompensation signs revelation of this peripheral vestibular dysfunction needs urgent medicine: possible etiotropic and obligate symptomatic therapy as well as spare vestibular rehabilitation exercises. Conclusion. Combination of oculogyric impairments and disturbances of postural control enables to improve accuracy of diagnostics in decompensated stage of vestibular neuronitis.

Stabilometric Characteristics of the Skateboarding Athlete from the Romberg Test

This research aims to find the characteristics of motor control at the level of body stability in skateboarding athletes from the city of Bogotá through a Romberg test with eyes open and eyes closed. The present study is of a descriptive cross-sectional type and the sample selection for the development of this research was for convenience, for which a direct invitation was performed at different skateboarding clubs in the city and the league skating Bogotá who supports the sport. The sample population corresponds to 30 people with an age between 22.86 +/- 7.88 years. Participants developed Romberg test with a duration of 30 s and under the modalities eyes open and closed on a platform of plantar pressure and stabilometry BTS P-Walk. Significant changes were found in comparison of the open and closed eyes tests in the lateral flexion of the spine (LSF) with p=0.018, body center of gravity with p=0.043, left center of gravity with p=0.018, showing improvements in body stability evaluation with eyes closed. It is evident that skateboarding athletes due to the dynamics and sports development on an unstable base present a high level of stability represented in mediolateral and anteroposterior stability and variability radii close to zero, additionally it is observed that work at eye level closed generates a better sports adaptation from the vestibular and peripheral system for motor control and balance.

Application of Core Strength Training in Badminton Footwork Teaching with Computer Aid

Badminton, as a national sport in China, has been strongly concerned by the Chinese people. In the sports arena, China’s badminton also occupies a leading position in the world. As for the core concept of badminton, how to effectively master the badminton footwork is also an important goal for every badminton lover in training and teaching. Core strength training, as a practical application in the teaching of badminton pace, occupies a position that cannot be ignored. Under the influence of a certain body center of gravity and conduction, core strength training has a flexible function to drive the physical strength. The training and teaching of badminton footwork of core strength is conducive to the flexible movement of limbs in badminton and plays an important role in the balance of power. Compared to traditional situation, there are many core strength training methods. However, problems still exist in some potential training. From the point of view of badminton step training, besides the use of both hands and brain, badminton has certain technical requirements on feet step and the coordination ability of the body, which requires the basic application of core strength training. In this regard, with the help of computer, this paper will focus on the nationwide badminton sports to conduct in-depth exploration and analysis on the teaching of core strength training.

The Impact of the Human Body Position Changes During Wheelchair Propelling on Motion Resistance Force: A Preliminary Study.

The aim of this research was to analyze the impact of the human body position changes caused by propelling a wheelchair with the pushrim propulsion on the value of motion resistance force. The discussed research works are in progress; therefore, the presented results should be treated as preliminary. The research was carried out in the group of six volunteers propelling a wheelchair of which frame was inclined, in respect to the horizontal plane, under the angle of 0 deg, 7 deg, and 14 deg. The area of the position variability of the human body center of gravity (COG) and the coefficients of wheelchair rolling resistance have been determined. Based on the measurements conducted, rolling resistance force FT and motion resistance force FR have been defined for three values of frame inclination angle. The determined force of rolling resistance Ft depended on the location of the COG of the human body and the value of the coefficients of rolling resistance of the front and rear wheels of a wheelchair. This force was a component of the resistance to motion FR, which also took into account the influence of gravity resulting from the inclination of the wheelchair on an inclined plane. For the tested inclination angles relative to the horizontal plane, the rolling resistance force ranged from 9.82 N to 22.81 N. Analyzing the variability of the rolling resistance force FT, it was found that for the final phase of the driving motion, it increased by 36% for the inclination angle of 0 deg and 43% for the inclination angle of 7 deg. Its increase was 48% for the inclination angle of 14 deg in relation to the human body position for the beginning of the driving motion. In the case of measuring the value of the resistance to motion FR, it was observed that, depending on the angle of the incline of the wheelchair, it ranged from 14.69 N to 256.33 N. The measurements conducted enabled the derivation of an analytical model for determining rolling resistance force depending on the position of the human body COG and the wheelchair inclination angle. The conducted research demonstrated the impact of the COG position on the changes of motion resistance force, thus expanding the state of knowledge, introducing a new parameter which, like a surface type and wheel type, affects motion resistances.

Targeted Training in Light of the Biomechanical Analysis foe the Skill of (Lift) and Its Impact on the Physical Level for Aerobic Dance Gymnasts

The aim of the research is to Biochemical characterization of lift skill in aerobic dance gymnasts. Determination of the quantitative values of some biochemical variables of the lift skill for aerobic dance gymnasts.Designing a training program using guided exercises in the light of (kinematic analysis) of the lift skill for aerobic dance gymnasts. First: Research Methodology: The researcher used the descriptive method (case study)The experimental method using single group and the two measurements (prior - post).Second: Research Sample (skill): lift skill for Italy aerobic dance gymnastic team in world champion 2017, which came in first place. Human Research Sample: the sample was selected with the intentional method for number of 8 aerobic gymnasts, who are registered in Egyptian Gymnastics Federation The time of (overall performance) of lift skill for aerobic dance gymnasts has taken period of time that reached (2,6) sec., time of (approaching) stage reached (0,4) sec., the time of stage of (jumping), (pushing and lifting), and (flying) has reached (0,5) sec., while the time of (landing) stage has taken (0,7) sec. The maximum height reached by the highest point in the body is (instep), which has reached (3.06) meters in the flying stage, while each of (right instep), (body gravity center), during the performance of the skill has reached (2,98) meters, (2,28) meters, respectively .The maximum speed rate was for the right foot in start of flying stage, which reached (15.39 m / s).

Influence of Different Ways of Carrying Luggage on the Center of Pressure Sway and Upper Body Center of Gravity

Influence of Different Ways of Carrying Luggage on the Center of Pressure Sway and Upper Body Center of Gravity

Finding Centre of Gravity of Yoga Asana Postures to support Self-Assisted Yoga Practice

Self-assisted yoga practice should ensure safety. Being in a wrong posture while doing practice may cause problems like fall or fractures in the bones. Practitioners of activities like yoga, sports etc. should maintain correct postures all through their practice. Maintaining a correct posture is influenced by Centre of Gravity whose location is based on distributing the entire body weight evenly for stability. In this paper, we propose a method to find the Centre of Gravity of any asana sequence. The location of Centre of Gravity will be used by the assistive system to instruct the practitioner how to alter their postures to avoid fall and enable to take-up perfect practice. Motion capture systems will give the details in the form of Biovision hierarchy format, from which the coordinate values of human joints can be accessed. Based on the segmentation method, whole body Centre of Gravity is calculated. We have used Vrikshasana for our experiment and yoga posture data for ten participants are used to find the Centre of Gravity variations. Data for two trails were acquired. CM Variations in segments like thigh, angle are calculated. From the results the instructors may find whether ankle or thigh’s position should be changed to maintain correct posture.

The Kinematics Analysis of Wu Yibing's Tennis Forehand Technique

Objective: Search for the forehand swing stroke technical characteristics and kinematics rules of the outstanding young men's tennis players in the world. It provides some theoretical basis of Tennis forehand technique for tennis coaches and athletes. Research object: The world's elite teenage male tennis player Wu Yibing. Research methods: Using two JVC GC-PX10AC high-speed cameras (50 frames per second), the scene of the 2017 international tennis federation youth masters competition was filmed in the field. And the video recorded in the field was analyzed with a 3-D Signal TEC V2.0C software. Conclusions: (A) In the stage of the backswing: Wu Yibing's shoulder and hip angle has been obviously reversed. He uses his elbow to guide the tennis racket to lead the whole movement smoothly and form an “arc”. Wu Yibing's right wrist, elbow and shoulder keep a certain linear velocity, increasing the racket acceleration time and space. And the process of the traditional forward swing acceleration is extended to the backward stage.(B)In the stage of hitting the ball: Wu Yibing's shoulder and hip angle has been obviously reversed. To gain more control to counteract the impact of the ball, his right shoulder joint remains a small angle to reduce the radius. In tennis racket contact ball moment, the right shoulder joint and right hip joint linear velocity were 0.94m/s and 1.06m/s respectively. The right wrist and elbow joint linear velocity achieve a high standard of 11.81m/s and 5.56m/s respectively. (C)In the stage of the follow up: Wu Yibing's body center of gravity is not moving forward and the body's center of gravity is slightly undulating. However, his body's moving to the left is obvious. His right shoulder angle changes a little and the elbow lifts a little, but the right elbow is in the substantial rotation around the torso to the left. To increase the friction of the racket to the ball, there is a reacceleration of Wu Yibing's right elbow after the racket touches the ball. And his right elbow is rapidly spinning with a twist of the wrist. So he can play a powerful upper spin ball.

Validity of the total body centre of gravity during gait using a markerless motion capture system

Purpose: The purpose of this study was to examine the validity of total body centre of gravity (COG) measurement during gait with markerless motion capture system (MLS) on the basis of values acquired with a marker-based motion capture system (MBS).Materials and methods: Thirty young healthy subjects walked on a flat surface as coordinate data from their bodies were acquired using the Kinect v2 (as a MLS) and Vicon systems (as a MBS). COG was calculated using coordinate data of the total body. Comparisons of COG ensemble curves in the mediolateral and vertical directions were performed between MLS and MBS throughout the gait cycle. The relative consistency between these systems was assessed using Pearson correlation coefficients.Results: The COG trajectory made by using MLS data followed the trend of the COG trajectory with MBS in the mediolateral direction. In the vertical direction, however, the COG trajectories did not match between two systems. High correlation coefficients (r > 0.79) were observed from 30% to 80% of the gait cycle. The greatest difference of COG between MLS and MBS in the mediolateral direction was 1.1 mm. Differences in the vertical direction appeared to be proportional to the distance between the participant and the Kinect v2 sensor.Conclusion: In the mediolateral direction, COG calculated with MLS data during gait was validated with COG calculated on the basis of a MBS. Further correction of systematic error is necessary to improve the validity of COG calculations in the vertical direction.

The Mechanical Principle of Slipping When Walking on Motion Surface with Different Acceleration

The contact force and the required friction coefficient were tested when people walking on motion platform with different accelerations by gait friction tester, forces acting on the body in different gait phase were analyzed, and the effect of the platform acceleration on mechanical principle of slipping was discussed. The results showed that the peak value of the required coefficient of friction (RCOF1) in landing phase increased with increasing of platform acceleration when people walking on accelerated motion platform, which was easy to slip; The peak value of the required coefficient of friction (RCOF2) in taking off phase decreased with larger acceleration, and the slipping tendency decreased. The required coefficient of friction could be decreased by adjusting the gait parameters and the motion of the body gravity center to reduce the possibility of slipping.

Comparison of crossover and jab step start techniques for base stealing in baseball

Base stealing is an important tactic for increasing the chance of scoring in baseball. This study aimed to compare the crossover step (CS) and jab step (JS) starts for base stealing start performance and to clarify the differences between CS and JS starts in terms of three-dimensional lower extremity joint kinetics. Twelve male baseball players performed CS and JS starts, during which their motion and the force they applied to the ground were simultaneously recorded using a motion-capture system and two force platforms. The results showed that the normalised average forward external power, the average forward–backward force exerted by the left leg, and the forward velocities of the whole body centre of gravity generated by both legs and the left leg were significantly higher for the JS start than for the CS start. Moreover, the positive work done by hip extension during the left leg push-off was two-times greater for the JS start than the CS start. In conclusion, this study has demonstrated that the jab step start may be the better technique for a base stealing start and that greater positive work produced by left hip extension is probably responsible for producing its larger forward ground reaction force.

Detection Method of Human Three-Dimensional Body Center of Gravity Based on Inclinometer Network

Detection Method of Human Three-Dimensional Body Center of Gravity Based on Inclinometer Network

Development of maximal speed sprinting performance with changes in vertical, leg and joint stiffness.

This study aimed to clarify the changes in stiffness variables when maximal speed sprinting performance was developed through long-term training. Nine well-trained male athletes performed maximal effort 60-m sprints before and after the completion of six months of winter training. In both experiments, sprinting motion at maximal speed was recorded with a high-speed camera and simultaneously ground reaction force (GRF) was measured. Spatiotemporal and stiffness variables were then calculated. Sprinting speed was significantly developed (P=0.001) through longer step length (P=0.049). While the leg stiffness did not change (from -539±126 to -558±180 N/kg/m) (P=0.686), the vertical stiffness significantly increased (P=0.001) from -1507±346 to -2357±704 N/kg/m due to increase and decrease in vertical GRF and descent of whole body center of gravity, respectively. Moreover, whereas knee joint stiffness remained constant (from -0.228±0.080 to -0.213±0.084 Nm/kg/°) (P=0.448), ankle joint stiffness was significantly developed (P=0.002) from -0.165±0.031 to -0.210±0.032 Nm/kg/° due to a respective increase and decrease in ankle plantarflexion moment and ankle dorsiflexion angle. The results demonstrate that the development of maximal speed sprinting performance through longer step length is accompanied by increases in vertical and ankle joint stiffness, and this shows the importance of vertical and ankle stiffness for improving maximal speed sprinting performance. Findings of this study may assist with the planning of training programs for athletes.

Human Center of Gravity Dynamics A New Parameter Of Motor Development Functions

A study of a new parameter of human growth and development was conducted. The percentage of the height of body gravity center to the stature in supine position was measured in males and females during the period of pre-puberty (l995), young and adult puberties (1995 and 1997) and male adults (1995). The parameters measured were weight, stature and the height of the gravity center. Data were calculated in obtaining arithmetic means, standard deviations of all parameters and the percentage of gravity point height to stature. The percentages of male and female means, as well as standard deviations, were compared statistically. It was shown that in the pre-puberty group the location of the gravity center to stature was the same in percentage in males compared to females, whereas in the adult group (1987, 1995) a higher percentage was found in males. Among males (1995) differences were found in the percentages, which might have been caused by differences of body typology; the mesomorphic type showed the highest percentage, the endomorphic type showed the lowest, whereas the ectomorphic type it was in between.

An Adaptive Dual-Window Step Detection Method for a Waist-Worn Inertial Navigation System

In waist-worn pedestrian navigation systems, the periodic vertical acceleration peak signal at body centre of gravity is widely used for detecting steps. Due to vibration and waist shaking interference, accelerometer output signals contain false peaks and thus reduce step detection accuracy. This paper analyses the relationship between periodic acceleration at pedestrian centre of gravity and walking stance during walking. An adaptive dual-window step detection method is proposed based on this analysis. The peak signal is detected by a dual-window and the window length is adjusted according to the change in step frequency. The adaptive dual window approach is shown to successfully suppress the effects of vibration and waist shaking, thereby improving the step detection accuracy. The effectiveness of this method is demonstrated through step detection experiments and pedestrian navigation positioning experiments respectively. The step detection error rate was found to be less than 0·15% in repeated experiments consisting of 345 steps, while the longer (about 1·3 km) pedestrian navigation experiments demonstrated typical positioning error was around 0·67% of the distance travelled.

Kinematics Characteristic of Exoskeleton Walking Robot for Older People

The movement processes of the older people during walking on level ground were captured by the high-speed video camera with the speed of 500 frames per second. The gait parameters of the older people during walking on level ground were obtained by the quantitative analysis of the successive photographs captured by the high-speed video camera. Kinematics features of the older people during walking on level ground were discussed. Along with the growth of the age, step velocity, step frequency and step length were reduced, and gait cycle was rising. According to the morphology of the older people during walking on level ground, a mechanical model was put forward to aid the design of the exoskeleton walking robot. The couple walking characteristics between the older wearer and the exoskeleton walking robot was studied. In the single support phase of the exoskeleton walking robot, the change of the hip joint was gradually decreased to provide the driving force for the stable walk, the change of the knee joint was increased and following decreased and then increased to forward the older people's body center of gravity, and the change of the ankle joint was gradually increased to reduce the impact force of the ground. The results would provide the basic theory to bionic references for improving the reasonable properties of the exoskeleton walking robot. This work would provide certain theoretical and practical base in developing the exoskeleton walking robot on bionic structural design.

1A15 フォースプレートのみを用いた歩行時の体重心位置計測(GS1-1:歩行・運動・姿勢制御(1))

1A15 フォースプレートのみを用いた歩行時の体重心位置計測(GS1-1:歩行・運動・姿勢制御(1))

Altura Percentual do Centro de Gravidade em Canoístas de Elite

O objetivo desse estudo foi comparar a altura do centro de gravidade e características antropométricas de atletas da equipe masculina nacional brasileira de canoagem velocidade com indivíduos não atletas.