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  • Author: Krzysztof Maćkała x
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A Kinematics Analysis Of Three Best 100 M Performances Ever

The purpose of this investigation was to compare and determine the relevance of the morphological characteristics and variability of running speed parameters (stride length and stride frequency) between Usain Bolt’s three best 100 m performances. Based on this, an attempt was made to define which factors determine the performance of Usain Bolt's sprint and, therefore, distinguish him from other sprinters. We analyzed the previous world record of 9.69 s set in the 2008 Beijing Olympics, the current record of 9.58 s set in the 2009 Berlin World Championships in Athletics and the O lympic record of 9.63 s set in 2012 London Olympics Games by Usain Bolt. The application of VirtualDub Programme allowed the acquisition of basic kinematical variables such as step length and step frequency parameters of 100 m sprint from video footage provided by NBC TV station, BBC TV station. This data was compared with other data available on the web and data published by the Scientific Research Project Office responsible on behalf of IAAF and the German Athletics Association (DVL). The main hypothesis was that the step length is the main factor that determines running speed in the 10 and 20 m sections of the entire 100 m distance. Bolt’s anthropometric advantage (body height, leg length and liner body) is not questionable and it is one of the factors that makes him faster than the rest of the finalists from each three competitions. Additionally, Bolt’s 20 cm longer stride shows benefit in the latter part of the race. Despite these factors, he is probably able to strike the ground more forcefully than rest of sprinters, relative to their body mass, therefore, he might maximize his time on the ground and to exert the same force over this period of time. This ability, combined with longer stride allows him to create very high running speed - over 12 m/s (12.05 -12.34 m/s) in some 10 m sections of his three 100 m performances. These assumption confirmed the application of Ballerieich's formula for speed development. In most 10 m sections of the 100 m sprint, the step length was the parameter that significantly determined the increase of maximal running speed, therefore, distinguishing Bolt from the other finalists.

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Asymmetry of Step Length in Relationship to Leg Strength in 200 meters Sprint of different Performance Levels

Asymmetry of Step Length in Relationship to Leg Strength in 200 meters Sprint of different Performance Levels

The purpose of this study was to quantify and compare asymmetry of stride length during 200 m sprint in different levels of performance. Six sprinters from national and regional levels participated in the study. They were assigned to 3 groups: school-boys (novice sprinters) junior (intermediate) and senior (advance - national and regional level) category. This study investigated selected kinematic parameters with special focus on stride length. The resulting values were measurements of each stride length (rounded-off to nearest full centimeter) during a 200 m sprint, using a manual stride measurement method. The findings indicate that the asymmetry of stride length exists in all categories, and the impact on decreasing velocities of the youngest sprinters (school-boys) are significantly associated with shorter strides, whereas cadence has little change. However, when a statistical adjustment was made for each group of runners it was found that more advanced runners did not have a significantly higher level of asymmetry with stride length at any given velocity.

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Structural asymmetry of foot arch formation in early school-age children

Summary

Study aim: the purpose of the study was to compare foot shapes in early school-age boys and girls.

Material and methods: the study included 90 boys and 98 girls aged seven to nine years old. The shape of the foot arch was examined using a podoscope. The longitudinal arch was assessed according to the Clarke angle value on the basis of Kasperczyk’s classification. The transverse arch was assessed according to the Wejsflog index. An analysis of variance, a post-hoc LSD test and a chi-square test were performed.

Results: normal transverse arches in both feet appeared in 84% of the examined children. An analysis of the average value of the Wejsflog index showed that it is similar and within limits in all of the test groups indiscriminately when it comes to gender and age. Normally, longitudinal arches in both feet occurr in 44% of children. The average value of Clarke’s index in a test group of school-age girls was within normal range while a functionally flattened foot appeared in the case of seven and eight-year-old boys.

Conclusions: the outcomes of the present study conducted on a randomly chosen group of developing boys and girls show that changes in foot structure are mostly symmetrical in nature (almost 90%), meaning that if the left foot is normal, the right one is normal, too. Gender had no effect on the foot build or arch type in either foot. The right and left feet showed symmetrical structure in the majority of the children.

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Biomechanical, Neuro-muscular and Methodical Aspects of Running Speed Development

Biomechanical, Neuro-muscular and Methodical Aspects of Running Speed Development

The purpose of present review article is to gather the most important findings in the field of speed development including biomechanical, motor and neuro-muscular factors. Maximum speed is a complex motor ability, which manifests itself in real sports situations and is an important factor in various sports disciplines. Efficiency of maximum running is defined with frequency and the length of stride. Both variables are mutually dependant; they also depend on the processes of central regulation of motor stereotype. From the biomechanical point of view, a running stride as a basic structural unit depends on eccentric-concentric muscular cycle of take-off action. Utilisation of elastic strength in muscular-tendon complex and pre-activation of the gastrocnemius muscle is highly important in this element. Maximum running is very limited hereditary motor ability with characteristic of reduced possibility for controlling movement. Cerebellum, co-activation of muscles in kinetic chain and the frequency of activation of motor units play important roles in controlling the activation of agonists and antagonists. The prime goal of training is to create an optimal model of motor stereotype in the zone of maximum speed. Such process has to be long term and methodical.

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Effects of Explosive Type Strength Training on Selected Physical and Technical Performance Characteristics in Middle Distance Running - a Case Report

Abstract

Introduction. Distance running performance is a simple function of developing high speeds and maintaining this speed as long as possible. Thus a correct running technique becomes an important component of performance. Technique is effective if the competitor can reach a better performance result with the same or lower energy consumption. The purpose of this investigation was to examine a six weeks application explosive type strength training on lower extremities power and maximum speed performance improvement in order to facilitate running technique in sub-elite male middle-distance runner. Material and methods. A sub-elite runner performed twice a week special exercises and running drills. He completed a pre and post-training jumping (SJ, CMJ, standing long jump, standing five jump) and speed (20 m from standing and flying start) field tests. For kinematical analysis, a video (SIMI Motion System) of a 10 m sprint from a 20 m flying start was collected. Results. Improvement occurred in all measurements but strong changes were evident in the 10 m from 20 flying start and in stride frequency from 3.90 to 4.01 Hz, due to decreasing of ground contact time from 160 to 156 ms. No strong evidence in the participant's running technique changes. Conclusion. This proved that six weeks of dynamic type strength program seems to improve neuromuscular characteristics of running speed and explosive power and no changes in running technique.

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Selected Determinants of Acceleration in the 100m Sprint

Abstract

The goal of this study was to examine the relationship between kinematics, motor abilities, anthropometric characteristics, and the initial (10 m) and secondary (30 m) acceleration phases of the 100 m sprint among athletes of different sprinting performances. Eleven competitive male sprinters (10.96 s ± 0.36 for 100 with 10.50 s fastest time) and 11 active students (12.20 s ± 0.39 for 100 m with 11.80 s fastest time) volunteered to participate in this study. Sprinting performance (10 m, 30 m, and 100 m from the block start), strength (back squat, back extension), and jumping ability (standing long jump, standing five-jumps, and standing ten-jumps) were tested. An independent t-test for establishing differences between two groups of athletes was used. The Spearman ranking correlation coefficient was computed to verify the association between variables. Additionally, the Ward method of hierarchical cluster analysis was applied. The recorded times of the 10 and 30 m indicated that the strongest correlations were found between a 1- repetition maximum back squat, a standing long jump, standing five jumps, standing ten jumps (r = 0.66, r = 0.72, r = 0.66, and r = 0.72), and speed in the 10 m sprint in competitive athletes. A strong correlation was also found between a 1-repetition maximum back squat and a standing long jump, standing five jumps, and standing ten jumps (r = 0.88, r = 0.87 and r = 0.85), but again only for sprinters. The most important factor for differences in maximum speed development during both the initial and secondary acceleration phase among the two sub-groups was the stride frequency (p<0.01).

Open access
Biomechanical Differences in the Sprint Start Between Faster and Slower High-Level Sprinters

Abstract

The purpose of this study was to examine the kinematic and kinetic differences of the sprint start and first two steps between faster and slower high-level sprinters. Twelve male sprinters were dichotomized according to personal best 60- and 100-m times. Each participant performed five starts under constant conditions. An eight-camera system was used for 3-D kinematic analysis. Dynamic forces at the start were determined with starting blocks mounted on bipedal force plates. Measures of front and rear block total force, front and rear block maximal force, time to front and rear block peak force, total force impulse, total horizontal and vertical impulse, front and rear block force impulse, time of block clearance, block leaving velocity and block leaving acceleration were collected. Between-group comparisons were made using independent samples t tests (p < 0.05) and by calculating effect sizes (Cohen’s d). Spearman’s correlation coefficients were used to examine the relationships between sprint start kinematics, kinetic measures and sprint performance. Significant between-group differences were observed in rear block total force (p = 0.0059), rear block maximal vertical force (p = 0.0037) and total force impulse (p = 0.0493). Only front block total force significantly correlated with 100 m sprint performance in both the slower and faster groups (r = 0.94 and 0.54, respectively; p = 0.05). Our findings suggest that faster sprinters show enhanced sprint start motor performance with greater force development than slower sprinters.

Open access
Changes in the Stiffness of Thigh Muscles in the Left and Right Limbs During Six Weeks of Plyometric Training in Volleyball Players

Abstract

Introduction. Monitoring muscle stiffness in athletes can be a good method of assessing fatigue caused by high training loads, and the early detection of fatigue can help prevent the occurrence of micro-trauma in the muscles that can cause contusions. The research carried out by Wilson et al. [1] confirmed that an optimal level of muscle stiffness is significantly correlated with high muscle loads. The aim of the current study was to determine changes in muscle stiffness of the left and right thighs during six weeks of plyometric training (PT) in volleyball players.

Material and methods. The study involved 16 volleyball players from the second-league Opole University of Technology Club (age = 21.12 ± 1.66 years, height = 191.62 ± 5.73 cm, and weight = 86.25 ± 6.66 kg) with at least five years of competitive experience (7.5 ± 2.44 years). Muscle stiffness was measured during three stages of the plyometric training using a MYOTON PRO device (Estonia).

Results. An RM-ANOVA analysis showed a significant difference in the resting stiffness of the semitendinosus (posterior thigh) muscles of the left and right limbs before the plyometric training began, but no significant differences were found in the stiffness of these muscles in the fourth or sixth weeks of training. The results of the measurement performed for the anterior muscles of the thigh did not reveal a significant difference in the stiffness of the left limb compared to that of the right limb in subsequent weeks of training.

Conclusion. The loads used in plyometric training in volleyball players caused a decrease in the differences in muscle stiffness between the left and right limbs, and in both limbs, adaptation trended towards an increase or a decrease in stiffness.

Open access