Kinesiology & Physical Education

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Biomechanical modeling as a practical tool for predicting injury risk related to repetitive muscle lenthening during learning and training of human complex motor skills
(SpringerOpen, 2016) Wan, Bingjun; Shan, Gongbing
Previous studies have shown that muscle repetitive stress injuries (RSIs) are often related to sport trainings among young participants. As such, understanding the mechanism of RSIs is essential for injury prevention. One potential means would be to identify muscles in risk by applying biomechanical modeling. By capturing 3D movements of four typical youth sports and building the biomechanical models, the current study has identified several risk factors related to the development of RSIs. The causal factors for RSIs are the muscle over-lengthening, the impactlike (speedy increase) eccentric tension in muscles, imbalance between agonists and antagonists, muscle loading frequency and muscle strength. In general, a large range of motion of joints would lead to over-lengthening of certain small muscles; Limb’s acceleration during power generation could cause imbalance between agonists and antagonists; a quick deceleration of limbs during follow-throughs would induce an impact-like eccentric tension to muscles; and even at low speed, frequent muscle over-lengthening would cause a micro-trauma accumulation which could result in RSIs in long term. Based on the results, the following measures can be applied to reduce the risk of RSIs during learning/training in youth participants: (1) stretching training of muscles at risk in order to increase lengthening ability; (2) dynamic warming-up for minimizing possible imbalance between agonists and antagonists; (3) limiting practice times of the frequency and duration of movements requiring strength and/or large range of motion to reducing micro-trauma accumulation; and (4) allowing enough repair time for recovery from micro-traumas induced by training (individual training time). Collectively, the results show that biomechanical modeling is a practical tool for predicting injury risk and provides an effective way to establish an optimization strategy to counteract the factors leading to muscle repetitive stress injuries during motor skill learning and training.
Factors influencing the effectiveness of axe kick in taekwon-do
(Archives of Budo, 2014) Wasik, Jacek; Shan, Gongbing
Background: Taekwon-do is famous for its powerful kicking techniques and the axe kick is the challenging one, aiming at kicking high section of an opponent. The relevance of the skill in the traditional version of taekwon-do is that a single strike might happen to reveal the winner. The main aims of the study were 1) the kinematic characteristics of the axe kick using motion capture technology and 2) the kinematics conditions leading to maximization of kick effectiveness. Material & Methods: Six International Taekwon-do Federation (ITF) practitioners participated in the study and each of them performed the axe kick (neryo chagi) three times. Using a 3D motion capture technology, selected parameters such as maximum kick foot velocity, durations of take-off, the upswing, the downswing as well as the whole kick and the kick leg angle at maximum velocity were quantitatively determined. The basic descriptive statistics (means & standard deviations) and correlation analyses were performed for revealing the dominant factors related to the kick. Results: The results indicate that the maximum kick power appears around 45º of the kick leg to vertical direction or 85-89% of one’s body height (i.e. the optimal offence/attack height) during the downswing. The variation of the optimal offense height depends on one’s body height, gender and race. And the keys for increasing the kick effectiveness are balanced weight transfer, large hip ROM for pre-lengthening hip extensors and follows an explosive foot downswing for maximizing kick-foot power. Conclusions: The above observations: the maximal kick power occurs around 45° of the kick-leg to the vertical direction during the downswing; shortening the downswing phase could increase the axe kick quality further.
The influence of X-factor (trunk rotation) and experience on the quality of the badminton forehand smash
(De Gruyter Open, 2016) Zhang, Zhao; Li, Shiming; Wan, Bingjun; Visentin, Peter; Jiang, Qinxian; Dyck, Mary; Li, Hua; Shan, Gongbing
No existing studies of badminton technique have used full-body biomechanical modeling based on three dimensional (3D) motion capture to quantify the kinematics of the sport. The purposes of the current study were to: 1) quantitatively describe kinematic characteristics of the forehand smash using a 15-segment, full-body biomechanical model, 2) examine and compare kinematic differences between novice and skilled players with a focus on trunk rotation (the X-factor), and 3) through this comparison, identify principal parameters that contributed to the quality of the skill. Together, these findings have the potential to assist coaches and players in the teaching and learning of the forehand smash. Twenty-four participants were divided into two groups (novice, n = 10 and skilled, n = 14). A 10-camera VICON MX40 motion capture system (200 frames/s) was used to quantify full-body kinematics, racket movement and the flight of the shuttlecock. Results confirmed that skilled players utilized more trunk rotation than novices. In two ways, trunk rotation (the X-factor) was shown to be vital for maximizing the release speed of the shuttlecock – an important measure of the quality of the forehand smash. First, more trunk rotation invoked greater lengthening in the pectoralis major (PM) during the preparation phase of the stroke which helped generate an explosive muscle contraction. Second, larger range of motion (ROM) induced by trunk rotation facilitated a whip-like (proximal to distal) control sequence among the body segments responsible for increasing racket speed. These results suggest that training intended to increase the efficacy of this skill needs to focus on how the X-factor is incorporated into the kinematic chain of the arm and the racket.
Unraveling mysteries of personal performance style; biomechanics of left-hand position changes (shifting) in violin performance
(PeerJ, 2015) Visentin, Peter; Li, Shiming; Tardif, Guillaume; Shan, Gongbing
Instrumental music performance ranks among the most complex of learned human behaviors, requiring development of highly nuanced powers of sensory and neural discrimination, intricate motor skills, and adaptive abilities in a temporal activity. Teaching, learning and performing on the violin generally occur within musico-cultural parameters most often transmitted through aural traditions that include both verbal instruction and performance modeling. In most parts of the world, violin is taught in a manner virtually indistinguishable from that used 200 years ago. The current study uses methods from movement science to examine the “how” and “what” of left-hand position changes (shifting), a movement skill essential during violin performance. In doing so, it begins a discussion of artistic individualization in terms of anthropometry, the performer-instrument interface, and the strategic use of motor behaviors. Results based on 540 shifting samples, a case series of 6 professional-level violinists, showed that some elements of the skill were individualized in surprising ways while others were explainable by anthropometry, ergonomics and entrainment. Remarkably, results demonstrated each violinist to have developed an individualized pacing for shifts, a feature that should influence timing effects and prove foundational to aesthetic outcomes during performance. Such results underpin the potential for scientific methodologies to unravel mysteries of performance that are associated with a performer’s personal artistic style.