EFFECT OF SOFT TISSUE ON DISSIPATING ENERGY & REDUCING FORCES

During impacts the soft tissues of the body move relative to the underlying skeleton and so the rigid body approximation used in most whole body biomechanical analysis can have limitations. Quantifying both the characteristics of the soft tissue motion and then its effects on joint moments and forces, as well as the forces and energy within the soft tissues themselves can be important for a fuller understanding of impact dynamics. During this part of the applied session examples from both modelling and experimental based research will be presented that demonstrate some of the effects soft tissue motion has on the system dynamics

DESCRIPTIVE ANALYSIS OF HIP AND KNEE JOINT LOADING DURING REVERSE ROUNDHOUSE KICK (HOOK) KARATE KICK PERFORMED IN TRAINING AND COMPETITION MODES

The purpose of this study was to examine hip and knee joint loading during the performance of the common reverse roundhouse or hook kick (Ura Mawash geri. Twenty eight black belt karate players performed hook kicks in two different ways, training kick and competition kick. Motion and force data were collected with a VICON motion analysis system and two Kistler force plates. 3D joint motions and joint moments about the hip and knee of both the support leg and kicking leg for all kicks were calculated in Visual3D. The maximum moments were more varied between kick types for the kicking leg but the joint angles were similar in most cases. Joint loading higher than in the literature for cutting actions were found, with cutting actions considered a risky action

HIP AND KNEE LOADING OF KARATE PLAYERS PERFORMING TRAINING AND COMPETITION STYLE VERSIONS OF A ROUNDHOUSE KICK

The main purpose of this study was to examine hip and knee joint loading during the performance of the common roundhouse kicking technique in both a training mode and in a competition mode. 15 black belt karate players performed roundhouse kicks in two different ways, basic kick and competition kick. Motion and force data were collected with a VlCON motion analysis system and two Kistler force plates. 3D joint motions and joint moments about the hip and knee of both the support leg and kicking leg for all kicks were calculated. The maximum moments were more varied between kick types for the kicking leg but the joint angles were similar in most cases. Joint loading comparable to the literature was found for joint previously examined but several high joint moments at extremes of motion were found in the supporting leg

FROM MEASUREMENT TO MODELLING IN SPORT COLLISIONS

Understanding the factors and the mechanism causing injury is one of the fundamental stages of the “sequence of prevention” of injury in sport (van Mechelen et al., 1992). Sports activities typically impose high and repetitive biomechanical demands on the neuro-musculo-skeletal system (e.g. Dufek & Bates, 1991; Trewartha et al., 2015), which research can try to capture and characterise. However, despite the progress of technologies and experimental methods, it is often impossible to directly measure the effects of specific sport events on the anatomical structures of the human body. In particular, the analysis of injury mechanisms in sports involving impacts (e.g. scrummaging and tackling in rugby, landing after a jump, or kicking in martial arts) needs to face a number of interdependent challenges, for which conventional approaches are not always adequate

SOFT TISSUE MOVEMENT IN THE LOWER LIMB DURING DROP JUMPS

Understanding loading on the human body and movement energetics is essential for researchers and practitioners to optimise training and investigate potential mechanisms of injury and adaptation. Recent work has suggested soft tissue movement relative to underlying bones during impact affects not only calculated loading but also metabolic cost. The aim of this study was to quantify the movement of the centre of mass of the soft tissues of the shank during high-impact, drop jump landings from 30 and 45 cm in healthy, adult males, and quantify the work done by these tissues. Soft tissue centre of mass moved by up to 0.038 m in the vertical direction (average: 0.021 m), and the soft tissues performed 2.9-3.5 J of work (4.1-6.4 J absolute work) during the landings. These results may hence have a significant effect on calculated joint torques and movement energetics

Modelling suppressed muscle activation by means of an exponential sigmoid function: Validation and bounds

This article was accepted for publication in the Journal of Biomechanics [© Elsevier Ltd.] and the definitive version is available at: http://dx.doi.org/10.1016/j.jbiomech.2015.01.009The aim of this study was to establish how well a three-parameter sigmoid exponential function, DIFACT, follows experimentally obtained voluntary neural activation-angular velocity profiles and how robust it is to perturbed levels of maximal activation. Six male volunteers (age 26.3±2.73 years) were tested before and after an 8-session, 3-week training protocol. Torque–angular velocity (T–ω) and experimental voluntary neural drive–angular velocity (%VA–ω) datasets, obtained via the interpolated twitch technique, were determined from pre- and post-training testing sessions. Non-linear regression fits of the product of DIFACT and a Hill type tetanic torque function and of the DIFACT function only were performed on the pre- and post-training T–ω and %VA–ω datasets for three different values of the DIFACT upper bound, αmax, 100%, 95% & 90%. The determination coefficients, R2, and the RMS of the fits were compared using a two way mixed ANOVA and results showed that there was no significant difference (p<0.05) due to changing αmax values indicating the DIFACT remains robust to changes in maximal activation. Mean R2 values of 0.95 and 0.96 for pre- and post-training sessions show that the maximal voluntary torque function successfully reproduces the T–ω raw dataset