Purpose The primary purpose of this study is to show and guide how to construct a large variety of behaviors in systems dynamic for sport science. Methods By applying a simple algorithm to networked agents, which could, conceivably, offer a straightforward way out of the complexity, computational mechanism which along with its dynamics (payoff, failure, and strategy) involved. Results The model starts with the probability that systemic risk potential such as failure spreads. Even in a very random structure commonly used in sports field, propagation of the potential is guaranteed by an arbitrary network property of a set of elements. Despite the intensive systemic potential, the opposite type of potential like absence of failure could also be driven when there has been a strong investment in protection through a heuristically evolved protection level. Conclusion The implementation still needs to be polished against what happens in the real sports world, but in general, applied conceptual principle and methodological techniques behind the network-agent based mechanisms could be useful for researchers those who need to use systemes dynamic to guard in sport science.
Purpose This study measured the haptic extroperception accuracy, that is, judging one hit position in a hand-held object. Especially, what factors associated the estimation of contact position when the impact is made at the grasped implement by hitting the ball. Methods Relative frequency and conditional probability based analysis verified that perceivers influenced not only the amount of pressure distinguished impressions by the coefficient of restitution but also the pressure distributions encoded impressions by the distance from the hand to the impact. Results Results conformed to previous invariant characteristic on dynamic touch in showing that perceiving the location of the impact of grasped objects, including dominant perceiving selectively modality, is constrained by inertial properties with such success requires appreciating the location of the implement’s center of percussion. Conclusion Investigated in this planes captured as a mechanical factor, we would suggest a broader hypothesis for further research into the effects of the rotational inertia related to haptic position accuracy in the hand-held object, and leading to different estimates of system function providing an account of generalization that accommodates of its varied aspects.
Purpose The purpose of this study was to investigate the effects of a functional fatigue protocol on lower extremity dynamic and static postural control. Methods A total of 20 physically active collegiate students participated in this study (ten males, ten females; age 22.5±2.7 years; mass 67.0±13.0 kg; height 168.0±8.9 cm). A unilateral stance with eyes closed for 10 seconds was performed to test static postural control using a balance force plate and single-leg drop landing on 30cm box was performed as a dynamic postural control test and captured using VICON motion analysis system. Results The results of this study showed an average heart rate of 176.3 beats/minute, an 18 rating on the perceived exertion scale, significant differences in blood lactate, and a static postural control deficit after fatigue as compared with before fatigue(p<.05). Dynamic postural control after fatigue changed landing strategy in the form of stiff landing. Knee flexion was decreased at initial contact and at peak vertical ground reaction force, also, both decreased valgus and internal rotation of knee joint. Conclusions This protocol may use for enhancing fatigue-endurance training as well as for inducing fatigue. Further, to ascertain a landing strategy, it is recommended to increase landing height to clearly observe changes in landing strategy.
PURPOSE This study aimed to analyze the dynamic posture stabilization and kinematic variables between visual feedback and Y-balance training groups during jump-landing. METHODS Thirty-eight male players (age: 22.6 ± 1.12 years, height: 175 ± 3.54 cm, weight: 65.5 ± 5.11 kg) were included in this study, and chronic ankle instability was checked using Cumberland Ankle Instability Tool (CAIT) and Balance Error Scoring System (BESS). They were randomly assigned to the Visual biofeedback (Training group: TG, n = 19) and Y-balance groups (Control group: CG, n = 19) for four weeks. TG performed balance training using the Biodex balance system (BBS) and CG performed training using the Y-balance system. During jump landing, time to stabilization (TTS), force plate (COP, GRF); joint angle and moment were collected and analyzed. All analyses were performed with SPSS 21.0, and Bonferroni was used for repeated measured ANOVA and post-hoc. RESULTS The results indicated that there was an interaction between TG and CG in terms of AP and ML directions of TTS (p < 0.05). AP/ML TTS of the TG for the post-test was smaller than that for CG (AP: p = 0.000; ML: p = 0.046). ML TTS of the TG for post-test was smaller than at pre-test (p = 0.041), and AP TTS of the CG for ankle joint moment (p < 0.05). There was an interaction between TG and CG in terms of dorsiflexion (DF) and plantarflexion (PF) of joint moment (p < 0.05). Ankle moment of the CG for post-test decreased than at pre-test (DF: p = 0.040, PF: p = 0.032), and ankle dorsiflexion moment of the CG for post-test was decreased than at pre-test (p = 0.046). CONCLUSIONS Balance ability was achieved more effectively through visual biofeedback training than Y-balance training. Therefore, we recommend balanced training with visual feedback on chronic ankle instability.
Vertical jumping is one of basic skills in many sports activities. Maximizing vertical jumping performance requires large “power”, which implies that one should generate force against the ground in a short period of time. In order to gain better understandings of how human musculo-skeletal system mechanically functions to achieve maximal power in vertical jumping, the proposed “dynamic catch” mechanism, one of “power amplification” mechanisms through the role of muscle-tendon interaction, was specifically reviewed base on the morphological and mechanical characteristics of lower limb muscle-tendon complex. By understanding basic structural and functional features of human muscle-tendon interaction, this review aims to provide basic scientific information for training and rehabilitation and promote convergence researches in related areas, such as sports biomechanics, mechanical engineering, and sports medicine.
Purpose The present study explored biological autonomy and control of function in circumstances that assessed a presumed relationship to an environmental cycle. An understanding of this behavior appeals to the organism-environment system rather than simply the organism—we seek to expose the laws that underlie end-directed capabilities by measuring biological characteristics (motor synchrony) in an environmental cycle (circadian temperature). Methods Participants (n = 24) at the University of Connecticut (Storrs, USA) and the Seoul National University (Seoul, Korea) served in the study. The production of in-phase bi-manual coordination was examined at different circadian points (allowing comparison of day-night temperature effects) in two experimental designs; (1) normal temperature embedded in a 24 hour cycle (5:00, 12:00, 17:00, and 24:00), and (2) normal versus abnormal temperature [artificially decreasing or increasing] while embedded at two points (5:00 am, 5:00 pm) during the circadian process. A typical bi-manual stability measure varied significantly as a function of the day-night temperature cycle. Results While (i) circadian effects under the artificially perturbed temperature manipulation were not straightforward along the day-night temperature cycle, (ii) the circadian effect divided by the ordinary circadian seems to be constant along the day-night temperature cycle. Conclusions The discovery of direct and robust relation between biological aspects (body temperature and motor synchrony) an environmental process (circadian temperature cycle) may echo adaptation of our biological system to the environment. This relation supports the claim that the organism and the environment should be considered as integrated system in which biological (or physical) dynamics takes place as a mutual factor.
The human foot is only part that directly contact between the body and the external environment, and is ideally positioned to provide sensory information to the Central Nervous System (CNS) during static and dynamic tasks. Through cutaneous mechanoreceptors located in the dermis, the foot is able to recognize touch pressure and vibration stimuli, which provide important feedback information used for the fine coordination of movements. The purpose of this study is to quantitatively examine the effect of changing the foot cutaneous sensory by temperature stimulus on maximal performance and muscle activation using wavelet technique. Sixteen healthy subjects volunteered to participate in this study (Male: Age 21.4±2.4years; Height 174.7±5.3츠; Weight 70.6±5.2kg; Female: Age 20.5±0.6years; Height 163.2±3.1cm; Weight 55.6±4.8kg). Sensory pressure thresholds were determined for the plantar surface of the foot using monofilament. Kinematic, kinetic and EMG data which relative to maximal performance were collected while squat jumping in each temperature condition(cool 12-15℃ normal 28-30℃ hot 45-48℃). Maximal jump height was significant higher in normal condition. Vertical GRF in normal condition showed higher peak value the other conditions. And then EMG signal were significant different between temperature conditions during maximal performance. By changed sensory feedback on temperature, one can alter maximal performance and muscle activation pattern. Cutaneous feedback is important in performance and neuromuscular control, and temperature changes significantly influence on lower extremity during maximal squat jump performance of healthy subjects.
