The effects of initial conditions and takeoff technique on running jumps for height and distance

Curved Approach in High Jump Induces Greater Jumping Height without Greater Joint Kinetic Exertions than Straight Approach

PURPOSE

The most height-specific jumping mode, the athletic high jump, is characterized as a running single-leg jump (RSLJ) from a curved approach. The main advantage of a curved approach is believed to be facilitation of bar clearance. However, the effect of a curved approach on center-of-mass (CoM) height generation has not been clarified. Here, we show that the curved RSLJ (C-RSLJ) is more suitable than the straight RSLJ (S-RSLJ) for CoM height generation.

METHODS

We collected data using motion capture from 13 male high jumpers (personal best, 2.02-2.31 m) that performed C-RSLJ and S-RSLJ. We then compared the energy generation contributing to CoM height (Evert) in each approach.

RESULTS

All participants attained greater CoM height in C-RSLJ than in S-RSLJ (difference, 0.055 ± 0.024 m). Three-dimensional joint kinematics and kinetics were similar between both approaches, except for the ankle plantar-flexion torque, which was smaller in C-RSLJ. The sum of positive work was comparable between the approaches, whereas the sum of negative work in C-RSLJ was significantly smaller than in S-RSLJ. The shank forward rotation induced a larger difference in Evert generation between C-RSLJ and S-RSLJ (0.80 ± 0.36 J·kg-1) than any other segment (≤0.36 J·kg-1).

CONCLUSIONS

Compared with a straight approach, a curved approach induces greater CoM height without increasing joint kinetic exertions during takeoff. The curved approach changes the initial condition of the takeoff and promotes the transformation of horizontal kinetic energy into Evert. This study provides novel practical perspectives for high jumpers and highlights the importance of segment biomechanics in human motor performance.

Acquisition of mechanical energy directly contributing to sideward propulsion in sidestep cutting manoeuvre

Humans seldom perform steady-state forward locomotion and often change locomotive direction through non-forward propulsion. Such manoeuvrability is essential for humans; however, unsteady-locomotion mechanics are understood less than steady-state locomotion because of the difficulty in research on unsteady locomotion with a wide range of variations. Here we show the body sideward propulsion mechanism in a sidestep cutting manoeuvre. We analysed the motion and ground reaction force of 10 males during the stance phase in 90° sidestep cutting with maximal efforts and determined the segmental components to the changes in the mediolateral-kinetic (E_ML), anteroposterior-kinetic (E_AP), and superoinferior-kinetic plus gravitational-potential energies (E_SI). The medial velocity and E_ML increased from the beginning to the end of the stance. The stance-leg shank rotation increased E_ML and decreased E_AP(early stance: 0.54 ± 0.17 and -1.49 ± 0.59 J/kg, late stance: 0.25 ± 0.14 and - 0.40 ± 0.17 J/kg), even while the knee and ankle work outflowed energy from the shank. The shank rotation induced over half the total increase in E_ML during the early stance (58 ± 7%). The stance-leg thigh rotation increased E_ML and decreased E_AP (early stance: 0.28 ± 0.12 and -0.26 ± 0.15 J/kg, late stance: 1.43 ± 0.26 and -0.47 ± 0.13 J/kg). We added the transformation from E_AP to E_ML by the shank and thigh rotations in the transverse plane to the sideward propulsion mechanisms, similar to the transformation from E_AP into E_SI in running single-leg jumps in a previous study. Coupled with previous studies, we prove the commonality in propulsion mechanisms across non-forward locomotion modes with different objective directions, which bridges the knowledge between unsteady locomotion modes.

Dynamic Characteristics of Approach Spike Jump Tasks in Male Volleyball Players

The approach running spike-jump (RSJ) is a crucial technique in the sport of volleyball. Two types of RSJs are commonly used for the volleyball spike attack: (1) RSJ with one leg (RSJ-1L) and (2) RSJ with two legs (RSJ-2L). The purposes of the current study were to compare the kinematic and kinetic differences between the RSJ-1L and RSJ-2L. Ten male college volleyball players performed spike jumps by striking a stationary ball at maximal jump height. Data were collected by six infrared Qualisys motion-capture cameras (180 Hz), two AMTI force platforms (1800 Hz), and recorded by Qualisys Track Manager software. The RSJ-1L demonstrated the faster three-step approach running velocity, greater vertical GRF, and ankle, knee, and hip joint moment, but less jump height, shorter last step length and push-off time, smaller knee and hip joint flexion angles at the initial foot-contact, and knee range of motion compared to the RSJ-2L. The current study contributed to the understanding of biomechanical differences of the volleyball spike jumps and can be used to adapt to the volleyball training.

Take-off velocity, force and power features manifestation in training exercises of athletes

The purpose of the study is to identify take-off velocity, force and power features manifestation in training exercises of athletes. 11 training exercises were subjected to metrological assessment. Analysis of take-off indicators allows us to assess their level individually for each athlete in each exercise. It greatly facilitates the coach’s task of individual exercises selection.

Biomechanical Characteristics of Single Leg Jump in Collegiate Basketball Players Based on Approach Technique

Our study investigated the characteristics of the biomechanics of lower extremities during running single leg jump (RSJ) in collegiate basketball players. Twelve division III male basketball players voluntarily participated in this study. They performed three trials of the running single leg jump with two approach speeds (fast and preferred) randomly. The kinematic data were collected by motion analysis system (200 Hz), and kinetic data were collected using the AMTI force platform (1000 Hz), and electromyography (EMG) data were recorded by the Delsys surface Electromyography (EMG) system (2000 Hz). Kinematic, kinetic and EMG signal were synchronized using EvaRT 4.6. Peak Ground reaction force, eccentric loading rate (ELR), gastrocnemius (GA) of pre-activation phase, and tibialis anterior (TA) of push-off phase were found significantly larger in the fast approach speed (p < 0.05). RSJ improves muscle activation level and stretch reflex. Higher activation of TA and GA during RSJ may have the benefit of decreasing risk of injury and jump training. Thus, it is helpful in muscle stretch adaptation.

Reliability of Head, Neck, and Trunk Anthropometric Measurements Used for Predicting Segment Tissue Masses in Living Humans

Soft and rigid tissue mass prediction equations have been previously developed and validated for the segments of the upper and lower extremities in living humans using simple anthropometric measurements. The reliability of these measurements has been found to be good to excellent for all measurement types (segment lengths, circumferences, breadths, skinfolds). However, the reliability of the measurements needed to develop corresponding equations for the head, neck, and trunk has yet to be determined. The purpose of this study was to quantify the inter- and intrameasurer reliability of 34 surface anthropometric measurements of the head, neck, and trunk segments. Measurements (11 lengths, 7 circumferences, 11 breadths, 5 skinfolds) were taken twice separately on 50 healthy, university-age individuals using standard anthropometric tools. The mean inter- and intrameasurer measurement differences were fairly small overall, with 64.7% and 67.6% of the relative differences less than 5%, respectively. All measurements, except for the right lateral trunk, had intraclass correlation coefficients (ICCs) greater than 0.75, and coefficients of variation (CVs) less than 10%, indicating good reliability overall. These results are consistent with previous work for the extremities and provide support for the use of the defined surface measurements for future tissue mass prediction equation development.

The effect of increasing strength and approach velocity on triple jump performance

The triple jump is an athletic event comprising three phases in which the optimal phase ratio (the proportion of each phase to the total distance jumped) is unknown. This study used a planar whole body torque-driven computer simulation model of the ground contact parts of all three phases of the triple jump to investigate the effect of strength and approach velocity on optimal performance. The strength and approach velocity of the simulation model were each increased by up to 30% in 10% increments from baseline data collected from a national standard triple jumper. Increasing strength always resulted in an increased overall jump distance. Increasing approach velocity also typically resulted in an increased overall jump distance but there was a point past which increasing approach velocity without increasing strength did not lead to an increase in overall jump distance. Increasing both strength and approach velocity by 10%, 20%, and 30% led to roughly equivalent increases in overall jump distances. Distances ranged from 14.05m with baseline strength and approach velocity, up to 18.49m with 30% increases in both. Optimal phase ratios were either hop-dominated or balanced, and typically became more balanced when the strength of the model was increased by a greater percentage than its approach velocity. The range of triple jump distances that resulted from the optimisation process suggests that strength and approach velocity are of great importance for triple jump performance.