Kinetic and Kinematic Analysis of Locomotion Speed of Higher Secondary Boys

The purpose was to analyze selected components of locomotion speed. Thirty school boys of age ranging from 17 to 19 year were selected as subject. Selected anthropometric and mechanical parameters were body weight, body height, leg length, maximum locomotion speed, leg power, stride length, stride frequency, body inclination, angle of leg placement in braking phase, push-off angle, horizontal projection of CG in braking phase, horizontal projection of CG in propulsion phase, horizontal velocity of CG in braking phase, horizontal velocity of CG in propulsion phase, velocity of swing leg in braking phase, velocity of swing leg in propulsion phase, angular velocity of thigh in propulsion phase, contact phase, flight phase, braking phase, and propulsion phase. The maximum locomotion speed was determined by a field test. Running action was filmed by a digital video camera with 120 fps for the distance between 40 to 50 m of the 100 m race. The anthropometric parameters were measured using standard procedure. The selected mechanical parameters were analyzed by motion analysis software. Results showed that weight, height, leg length, stride length, stride frequency had higher positive correlation with maximum locomotion velocity, whereas, contact phase, flight phase and propulsion phase had higher negative correlation with maximum locomotion velocity.

The Impact of the Human Body Position Changes During Wheelchair Propelling On Motion Resistance Force

Purpose - The aim of this research was to analyse the impact of the human body position changes caused by propelling a wheelchair with the pushrim propulsion on the value of motion resistance force. Material and methods - The research was carried out in the group of six persons propelling a wheelchair whose frame was inclined, in respect to the horizontal plain, under the angle of 0°, 7° and 14°. The area of the position variability of the human body centre of gravity and the coefficients of wheelchair rolling resistance have been determined in the research. Results -The results obtained, depending on the wheelchair inclination angle, ranged from 9.82 N to 22.81 N. In addition, it has been determined that the percentage increase in rolling resistance force, with the body position proper for the initial propulsion phase, in relation to the body position for the final propulsion phase, amounted to: 35.6% for the inclination angle of 0°, 43.2% for the inclination angle of 7°, and 48.3% for the inclination angle of 14°. Conclusion - the research done demonstrated the impact of the centre of gravity position change on the change of motion resistance. Thus, the research supplemented knowledge with a new parameter which, like a surface type and wheel type, affects motion resistances.

Improving speed motor skills in women’s football-tennis for elite players

Football-tennis is a sport that appeared in 1922, and in 1940, the first official regulation was issued. It can be an individual or team sport with single, double or triple events, plus the mixed doubles and triples, which is played by both men and women. Football-Tennis is not recognised nationally and globally as other sports, therefore, in most cases, no emphasis is placed on the physical, technical and tactical training where to take into account the regularisation of training depending on the competitive period in which athletes are at a specific time. The study was conducted on elite athletes representing the Romanian team in international competitions and having a competitive experience of 10-15 years. The motor ability tested in this paper was the speed of movement, which was measured with the help of the OptoJump device. The test applied checked the running speed over the distance of 5 meters. Two tests were performed by players as follows: an initial one, which aimed to determine the level of manifestation of their speed of movement, and a final one, which aimed to determine the level of progress following the application of the centralised training programme. The main objective was to find out: step length, flight time, contact time, flight phase, flat foot, propulsion phase, steps/m, height, angle of inclination and speed in m/s.

Intra-Segment Coordination Variability in Road Cyclists during Pedaling at Different Intensities

Background: The purpose of this study is to examine the lower extremity intra-segment coordination and variability of road cyclists during pedaling at different intensities. Methods: Eleven semi-professional road cyclists perform four trials at workloads of 50%, 75%, 100%, and 125% of their maximum power output in a randomized order. Thigh, shank, and foot range of motions (ROM) and the coordination and variability of these segments are compared across different pedaling intensities. Results: Foot ROM in the sagittal plane and shank ROM in the transverse plane are significantly different between different pedaling intensities. Moreover, specific coupling patterns and variabilities are observed across the pedaling cycle; however, they were not significantly different across different pedaling intensities in four pedaling phases. Conclusion: The results highlight the role of knee extensors and plantar flexors during the first and second half of the propulsion phase of pedaling, respectively. Thigh abduction dominancy with faster movement compared to the shank indicates a more valgus stress during the propulsive phase of pedaling, which can increase the risk of overuse injuries in the knee. Moreover, the smaller variability during the transition between the propulsive and recovery phases indicates a reduction in degrees of freedom and may increase the risk of overuse injuries.

Solar Wind Measurements from the Planetary Magnetometer Onboard the BepiColombo Spacecraft

<p>BepiColombo is en-route to Mercury. The boom carrying the planetary magnetometers (MPO-MAG instrument) was deployed in space on 25th of October in 2018. After the deployment, the magnetic disturbances arising from the spacecraft have been greatly decreased. Since the deployment, the fluxgate sensors have been monitoring the magnetic field continuously except for the solar electric propulsion phase. Extensive calibration and data processing activities have since enabled us to greatly decrease spacecraft-generated <br>disturbances in the magnetic field observations; these activities constitute a key step towards making the data <br>suitable for scientific analysis. We present a few cases of identified magnetic disturbances, discuss the challenges <br>they pose, and compare methods to clean the data. We also compare MPO-MAG measurements to observations by the <br>Advanced Composition Explorer (ACE) solar wind monitor, thereby highlighting the small-scale nature and rapid <br>evolution of interplanetary magnetic field (IMF) variations. We conclude with an overview of the scientific <br>goals of the instrument team for the in-orbit mission phase.</p>

DETECTION OF FORWARD PROPULSION USING A SINGLE ACCELEROMETER DURING WALKING IN OLDER POPULATION

In the geriatric population, diminished ankle joint moment and weak plantar flexor can contribute to inadequate forward propulsion and negatively impact gait performance, which can lead to poor energetic efficiency. Detection of propulsion phase can help identify gait normality and guide rehabilitation therapy to improve functional performance. Current methods have limited application in daily life and unsuitable for continuous monitoring. In this study, we aim to develop algorithms based on a single sensor attached to the shin to accurately detect propulsion phase. Six elderly (age: 73 years, BMI: 30.4) were recruited. Participants walked at their normal pace while wearing a plantar pressure system and an accelerometer on the shin. The pressure data was used to define the beginning of the propulsion phase when the pressure switched from the heel to the forefoot. A wavelet algorithm was developed to automatically detect the start and end points of propulsion phase using an accelerometer. The Bland-Altman method was used to evaluate the agreement between these methods. Pearson’s Coefficient was used to quantify the correlation. Based on the Bland-Altman analysis, A high agreement was obtained between the proposed method using accelerometer and pressure sensor (bias =9 ms, precision = 30 ms). Both algorithms are significantly correlated (r = 0.85, p<0.05). This study presents an innovative algorithm to automatically detect the propulsion phase for older adults during walking. Using wearable could facilitate the capture of propulsion phase during living activity, which might provide more insights into the mechanism of walking during rehabilitation therapy.

USAIN BOLD – BIOMECHANICAL MODEL OF SPRINT TECHNIQUE

The aim of this research was to determine which kinematic parameters generate the maximum sprint speed of the world’s fastest sprinter, Usain Bolt. The biomechanical parameters of a double sprint step, using a 2D kinematic analysis under conditions of the realization of its maximum velocity were analyzed. The APAS computer system was used for the kinematic analysis. The data was recorded with three digital cameras CASIO EX-F1 with a frequency of 300 Hz, while the cameras were connected to one another and synchronized. The measurements were performed at the international athletics competition IAAF World Challenge in Zagreb, Croatia. Bolt reached a maximum speed of 12.42 m·s-1 in the section between 70 and 90 meters. His average stride length in this section was 2.70 m at an average frequency of 4.36 strides/s. His average contact time was 0.86 s and the average duration of his flight phase was 0.145 s. He developed a maximum vertical ground reaction force of 3956.74 N. This force corresponds to 4.1 times the weight of the athlete. The ratio between his braking and propulsion phase was 37.3% : 62.7%, which is a good indicator of an economical running technique. The maximum speed of Usain Bolt is a combination of optimal anthropometric characteristics, motor abilities, and an extremely rational technique of sprinting gait.

Interlimb Force Coordination in Bipedal Dance Jumps: Comparison Between Experts and Novices

Bipedal tasks require interlimb coordination that improves with practice and acquisition of skills. The purpose of this study was to compare interlimb force coordination during dance-specific rate-controlled consecutive bipedal jumps (sautés) between expert dancers and nondancers. To analyze coordination of vertical ground reaction forces recorded under each leg, the vector coding approach was used. Although there were no differences in the patterns of interlimb force coordination between groups, the dancers exhibited less variability of interlimb force coordination during the transition phase from weight acceptance to propulsion as well as during the propulsion phase itself. The interlimb force coordination variability was associated with task performance only during the transition phase, which highlights the potential importance of control during this phase. In conclusion, expert dancers were better at reducing interlimb force coordination variability during the task-relevant transition phase, which was related to better performance at maintaining jump rate and jump height consistency.