Agreement between force and deceleration measures during backward somersault landings (original) (raw)
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Journal of sports science & medicine, 2010
In most common bilateral landings of vertical jumps, there are two peak forces (F1 and F2) in the force-time curve. The combination of these peak forces and the high frequency of jumps during sports produce a large amount of stress in the joints of the lower limbs which can be determinant of injury. The aim of this study was to find possible relationships between the jump height and F1 and F2, between F1 and F2 themselves, and between F1, F2, the time they appear (T1 and T2, respectively) and the length of the impact absorption phase (T). Thirty semi-professional football players made five countermovement jumps and the highest jump of each player was analyzed. They were instructed to perform the jumps with maximum effort and to land first with the balls of their feet and then with their heels. All the data were collected using a Kistler Quattro Jump force plate with a sample rate of 500 Hz. Quattro Jump Software, v.1.0.9.0., was used. There was neither significant correlation betwee...
Journal of Applied Biomechanics, 2012
It is common practice to study jump landing mechanics by having subjects step off a box set at a certain height instead of landing from a jump. This practice assumes that the landing mechanics are similar between stepping off a box and a countermovement jump as long as the heights can be matched. The mechanics of the two methods had never been compared when landing from identical heights. Thus, the purpose of this study was to compare the mechanics of landing from a countermovement jump to landing from a step-off. Participants performed three maximal countermovement jumps. The mechanics of one countermovement jump was compared with a center of mass fall height matched step-off landing. The step-off landing showed a more rapid time to peak ground reaction force (GRF) in both genders and greater GRF peak and loading rate in males only. No difference was observed between joint angles at initial contact; however, the countermovement jump showed significantly greater joint flexion angles...
Subtalar Pronation Does Not Influence Impact Forces or Rate of Loading During a Single-Leg Landing
Journal of athletic training
contributed to conception and design; acquisition and analysis and interpretation of the data; and drafting, critical revision, and final approval of the article. Bruce M. Gansneder, PhD, contributed to analysis and interpretation of the data and critical revision and final approval of the article. Sandra J. Shultz, PhD, ATC, CSCS, contributed to conception and design; acquisition and analysis and interpretation of the data; and drafting, critical revision, and final approval of the article.
The aim of this study was to compare the take-off's kinetic and kinematic variables between three types of jumps from a standing position: counter movement jump with arm swing CMJa), standing back somersault with landings on the spot (BSls) and standing back somersault with rear displacement at landing (BSld). Five elite level male gymnasts (age 23.17 ± 1.61 years; height 165.0 ± 5.4 cm; weight 56.80 ± 7.66 kg) took part in this investigation. A force plate and a 3D movement analysis system were synchronized and used for data collection. Statistical analysis via non-parametric Kruskal-Wallis test showed a significant difference between the take-off variables. The vertical component of force, peak power, impulse and displacement of the centre of mass were significantly different (P<0.01). Similarly, the horizontal component of force, maximum speed, peak power and displacement of the centre of mass were significantly different (P<0.01). However, vertical velocity remained relatively constant. In conclusion, the standing back somersaults performed on the spot's variables (without back displacement) were very similar to the ones analysed during counter movement jump with arm swing. The standing back somersault with landing on the spot allowed better force impulse. This was facilitated by a take-off closer to the centre of mass, unlike the standing back somersault with rear displacement in landing. Analysing kinetic and kinematic together, allowed the endorsement of linear regression equations enabling the prediction of some variables from others.
Gait & posture, 2015
Time to stabilization (TTS) is the time it takes for an individual to return to a baseline or stable state following a jump or hop landing. A large variety exists in methods to calculate the TTS. These methods can be described based on four aspects: (1) the input signal used (vertical, anteroposterior, or mediolateral ground reaction force) (2) signal processing (smoothed by sequential averaging, a moving root-mean-square window, or fitting an unbounded third order polynomial), (3) the stable state (threshold), and (4) the definition of when the (processed) signal is considered stable. Furthermore, differences exist with regard to the sample rate, filter settings and trial length. Twenty-five healthy volunteers performed ten 'single leg drop jump landing' trials. For each trial, TTS was calculated according to 18 previously reported methods. Additionally, the effects of sample rate (1000, 500, 200 and 100 samples/s), filter settings (no filter, 40, 15 and 10 Hz), and trial l...
A Comparison of Multiple Forward Somersault Dives from the 3M Springboard: A Case Study
2014
The aim of this study was to examine the differences in the angular velocity profiles and key positional angles of multiple forward somersault dives from the 3m springboard. One internationally ranked male diver performed the forward 1½, 2½, 3½ pike (P) dives while a second diver performed the 4½ tuck (T) dive. High speed video footage and inertial measurement units (IMU) were used to determine eight biomechanical variables. Results indicate that the diver performing the 4½T had a 177 deg/s increase in the angular velocity plateau and held onto his somersault position for 0.26s longer when compared to the 3½P. The forward 4½T takeoff angles were similar to those used in the 2½P and 3½P, but were slightly under rotated at entry. The IMUs proved to be a suitable analysis tool for springboard diving coaches wanting ‘quick turnaround’ performance analysis.
2019
This study aimed to investigate how elite Chinese gymnasts manage the landing impact from a backward somersault. Six international-level male gymnasts performed backward somersault tests with a synchronous collection of kinematics (250 Hz), ground reaction forces (1000 Hz), and sur face electromyography (2000 Hz). A 19-segment human model was developed and lower extremity joints torques were calculated by means of a computer simulation. The angles of the lower extremity joints initially extended and then flexed. These angular velocities of extension continued to decrease and the joint torques changed from extensor to flexor within 100 ms before touchdown. The angles of the hips, knees, and ankles flexed rapidly by 12°, 36°, and 29°, respectively, and the angular velocities of flexion, flexor torque , and electromyography peaked sharply during the initial impact phase of the landing. The angles of the hips, knees, and ankles flexed at approximately 90°, 100°, and 80°, respectively. The torques were reversed with the extensor torques, showing a relatively high level of muscle activation during the terminal impact phase of the landing. The results showed that the international-level gymnasts first extended their lower extremity joints, then flexed just before touchdown. They continued flexing actively and rapidly in the initial impact phase and then extended to resist the landing impact and maintain body posture during the terminal impact phase of the landing. The information gained from this study could improve our understanding of the landings of elite gymnasts and assist in injury prevention.
2016
The aim of this case study was to determine the practical application of 3D inertial measurement units and compare angular velocity profiles, key position angles and event timings for the backward 2½ somersaults with 1½ twists (5253B). One male diver performed 11 trials of the 5253B while 3D inertial measurement units (IMU) and high speed video were used to measure kinematic variables. Peak angular velocity about the somersault and twist axes were 900±11deg/s and -1435±28.deg/s, with highly consistent patterns displayed for total flight time (<1%) and peak angular velocity (=2%). A comparison between the 5253B and the backward 2½ somersaults dive (205B) indicated significant kinematic differences at take-off, flight and entry. IMU provide a quick and practical analysis tool for coaches wanting to monitor their athlete’s daily performance.
Journal of sports science & medicine, 2007
The objectives were to determine the number of trials necessary to achieve performance stability of selected ground reaction force (GRF) variables during landing and to compare two methods of determining stability. Ten subjects divided into two groups each completed a minimum of 20 drop or step-off landings from 0.60 or 0.61 m onto a force platform (1000 Hz). Five vertical GRF variables (first and second peaks, average loading rates to these peaks, and impulse) were quantified during the initial 100 ms post-contact period. Test-retest reliability (stability) was determined using two methods: (1) intra-class correlation coefficient (ICC) analysis, and (2) sequential averaging analysis. Results of the ICC analysis indicated that an average of four trials (mean 3.8 ± 2.7 Group 1; 3.6 ± 1.7 Group 2) were necessary to achieve maximum ICC values. Maximum ICC values ranged from 0.55 to 0.99 and all were significantly (p < 0. 05) different from zero. Results of the sequential averaging a...