UPPER BODY MOVEMENTS IN ELITE JAVELIN THROWS

INTRODUCTION - For an athlete to compete at an international level he will not only need the raw materials necessary for the event, but an effective training programme. That will enable him to utilise these resources to the full. It is well accepted that exercise prescription must match the mode of training to the desired effect. This is embodied in the specificity principle which states that training adaptations are specific to the cells and their structural and functional elements that are overloaded (McCafferty & Horvath, 1977).Hence, to provide training advice to the elite javelin thrower exact details of the thrower's movements during the event must be known. Otherwise, developing a training programme to fit the thrower's requirements will be impossible. It was the aim of this study to quantify the upper body movements of a group of elite javelin throwers when performing at the highest level of competition. Every throw of12 athletes competing in the men's javelin final of the 1995 World Championships were filmed and, subsequently analysed. Filming was conducted using 2 phase-locked High speed Photosonics 1PL cine cameras which were zoomed on the javelin runway such that all of the thrower's movements incorporating the last few cross-over strides, the delivery and the first few meters of the javelin6gM after release, were in full view. Calibration of this area was achieved by mounting Rflective spherical markers on a system of vertical poles that were arranged to surround a 7 m x 4 m x 3.2 m volume. Three dimensional coordinates of the markers were generated using an Elta Ill tachymeter. The films developed and the best performances of the competitors were digitised using a sys-tem developed by Bartlett (1 990) compatible with Acorn Archimedes computers. RESULTS -Analysis of the best throws by the three medallists (all over 86 m) showed that all three athletes achieved release speeds in excess of 30 m.s-I. However, the way in which each athlete achieved such a high speed was very different indeed. For example, the gold and silver medallists were found to laterally align the trunk during the delivery in a similar manner. Nevertheless, the path of the javelin grip in a lateral direction differed by 54 cm between the two athletes. Furthermore, angular velocities of the elbow joints in extension were found to range between 45.0 rad.s-I and 26.5 rad.s! Similarly the movement of the upper arm during the delivery was a combination of extension, horizontal flexion and abduction, the angular velocities of which ranged from 21.8rad.s-I to 15.6 rad.s-I. Medial rotation angular velocities were as high as 45.0 rad.s-I indicating that this also is a important contributor to the release speed of the javelin. CONCLUSIONS - These results suggest that the patterns of muscular activation or the muscles used to accelerate the javelin were very different for the three medal lists. It would therefore seem appropriate that the training programmes of each athlete should be different and designed very specifically to meet their unique movement pattern. Examining the contribution of the upper body musculature to the release speed of the javelin is an aim of future research. REFERENCES Bartlett, R.M. (1 990). A biomechanical analysisprogramme package. Unpub. Mas. Thes.McCafferty, W.B. & Horvath, S.M. (1977).Research Quarterly, 48, 358-37 1

Persistent homology-based gait recognition robust to upper body variations

Gait recognition is nowadays an important biometric technique for video surveillance tasks, due to the advantage of using it at distance. However, when the upper body movements are unrelated to the natural dynamic of the gait, caused for example by carrying a bag or wearing a coat, the reported results show low accuracy. With the goal of solving this problem, we apply persistent homology to extract topological features from the lowest fourth part of the body silhouettes. To obtain the features, we modify our previous algorithm for gait recognition, to improve its efficacy and robustness to variations in the amount of simplices of the gait complex. We evaluate our approach using the CASIA-B dataset, obtaining a considerable accuracy improvement of 93:8%, achieving at the same time invariance to upper body movements unrelated with the dynamic of the gait.Ministerio de Economía y Competitividad MTM2015-67072-

Positive/Negative Emotion Detection from RGB-D upper Body Images

International audienceThe ability to identify users'mental states represents a valu-able asset for improving human-computer interaction. Considering that spontaneous emotions are conveyed mostly through facial expressions and the upper Body movements, we propose to use these modalities together for the purpose of negative/positive emotion classification. A method that allows the recognition of mental states from videos is pro-posed. Based on a dataset composed with RGB-D movies a set of indic-tors of positive and negative is extracted from 2D (RGB) information. In addition, a geometric framework to model the depth flows and capture human body dynamics from depth data is proposed. Due to temporal changes in pixel and depth intensity which characterize spontaneous emo-tions dataset, the depth features are used to define the relation between changes in upper body movements and the affect. We describe a space of depth and texture information to detect the mood of people using upper body postures and their evolution across time. The experimentation has been performed on Cam3D dataset and has showed promising results

The Walking Brain: factors influencing human gait

Human walking is a standardized, repeatable and rhythmic locomotor act, with biomechanical patterns reported as roughly common to all healthy individuals. However, some gait patterns could be affected by cognitive, social and cultural factors. This mini-review aims at investigating top-down related differences in walking healthy patterns due to the above factors. The reviewed literature reported that socio-economic factors are at the basis of differences in pedestrian walking speed, related to the pace of life: faster speed was found in industrialized countries than in developing ones. Furthermore, it was suggested that the ancient division between men and women in hunters and gatherers, respectively, could be at the basis of gender visual differences and, in turn, in upper body movements during walking, with women walking with a more stable head. Interestingly, changes in gait speed did not affect cortical resources needed for spatial cognition, whereas a cognitive task may affect the gait speed. The most reliable parameters, poorly affected by psycho-social factors, resulted the symmetry of limb movements and the ratio between stance and swing duration. The latter was found close to the irrational number called golden ratio, providing a fractal structure to human gait cycle. Both these parameters are at the basis of the harmony of human walking, a feature maintained also in presence of top-down driven gait modifications

KINECTWheels: wheelchair-accessible motion-based game interaction

The increasing popularity of full-body motion-based video games creates new challenges for game accessibility research. Many games strongly focus on able-bodied persons and require players to move around freely. To address this problem, we introduce KINECTWheels, a toolkit that facilitates the integration of wheelchair-based game input. Our library can help game designers to integrate wheelchair input at the development stage, and it can be configured to trigger keystroke events to make off-the-shelf PC games wheelchair-accessible

Quantification of upper body movements during gait in older adults and in those with Parkinson's disease: impact of acceleration realignment methodologies.

The upper body accelerations of people with Parkinson’s disease (PD) measured by inertial measurement units (IMUs) may contribute towards diagnostic algorithms and help track disease progression. Before extracting variables related to upper body motion, acceleration signals require realignment to a global reference; however, the impact of these techniques on the resulting upper body variables is unclear. Therefore, the aim of this investigation was to examine the impact of four different realignment methods designed to correct acceleration signals on a range of upper body variables in older adults and in patients with PD. Two minutes of continuous gait were measured in 54 community-dwelling older adults (71.1 �6.7 years) and 60 people with PD (age: 68.5 � 9.1 years). Three IMUs placed on the 5th lumbar vertebra, 7th cervical vertebra and the back of the head recorded the acceleration of the upper body. A selection of upper body variables sensitive to impaired upper body control in PD and four acceleration realignment methods were compared. A mixed-model ANOVA showed that the choice of realignment method significantly affected the values of upper body variables as well as their ability to discriminate between the PD and control group. Our findings indicate researchers and clinicians should be cautious when comparing upper body variables extracted from IMUs using different realignment methods, and consideration of realignmenttechnique will be important when identifying the most sensitive markers of disease presence and progression. Therefore, it’s strongly recommend that researchers consider and report their realignment methods when assessing upper body variables during gai

Odd Sensation Induced by Moving-Phantom which Triggers Subconscious Motor Program

Our motor actions are sometimes not properly performed despite our having complete understanding of the environmental situation with a suitable action intention. In most cases, insufficient skill for motor control can explain the improper performance. A notable exception is the action of stepping onto a stopped escalator, which causes clumsy movements accompanied by an odd sensation. Previous studies have examined short-term sensorimotor adaptations to treadmills and moving sleds, but the relationship between the odd sensation and behavioral properties in a real stopped-escalator situation has never been examined. Understanding this unique action-perception linkage would help us to assess the brain function connecting automatic motor controls and the conscious awareness of action. Here we directly pose a question: Does the odd sensation emerge because of the unfamiliar motor behavior itself toward the irregular step-height of a stopped escalator or as a consequence of an automatic habitual motor program cued by the escalator itself. We compared the properties of motor behavior toward a stopped escalator (SE) with those toward moving escalator and toward a wooden stairs (WS) that mimicked the stopped escalator, and analyzed the subjective feeling of the odd sensation in the SE and WS conditions. The results show that moving escalator-specific motor actions emerged after participants had stepped onto the stopped escalator despite their full awareness that it was stopped, as if the motor behavior was guided by a “phantom” of a moving escalator. Additionally, statistical analysis reveals that postural forward sway that occurred after the stepping action is directly linked with the odd sensation. The results suggest a dissociation between conscious awareness and subconscious motor control: the former makes us perfectly aware of the current environmental situation, but the latter automatically emerges as a result of highly habituated visual input no matter how unsuitable the motor control is. This dissociation appears to yield an attribution conflict, resulting in the odd sensation

Exploring the effects of peripheral sensibility on visuospatial and postural capacities during goal-directed movements in long-term Tai Chi practitioners

BackgroundFalls are directly related to visuospatial ability and postural stability. Perturbations of upper body movements pose a challenge to older adults and may cause falls. This study investigated visuospatial ability and postural stability during goal-directed upper body movements between the Tai Chi and control groups and tried to connect them with their sensations.Materials and methodsThirty-seven older adults were recruited to perform the touch (TT) and blind touch (BTT) tasks. The target positioning error (TPE), ankle proprioception, tactile sensation, time to stabilization (TTS), and maximum displacement (Dmax) of the center of pressure trajectory were compared between the groups during the tasks. The relationships of visuospatial ability and postural stability to proprioception and tactile sensation were investigated.ResultsDmax in the mediolateral (DmaxML) direction decreased during BTT compared to TT among the Tai Chi group but not the control group. Compared to the control group, less Dmax in the anterio-posterior (DmaxAP) direction, and shorter TTS in AP/ML (TTSAP/TTSML) directions were observed among the Tai Chi group. Compared to TT, DmaxAP decreased during the BTT. The Tai Chi group had less TPE in the vertical (TPEV) direction and in three-dimensional space. Among the Tai Chi group, TPEV, TTSML, and DmaxAP were correlated to their proprioception during plantarflexion; TTSAP was correlated to tactile sensation at the great toe during the TT and BTT; DmaxAP was correlated to tactile sensation at the great toe during the TT. Among the control group, TTSML was correlated to ankle proprioception during dorsiflexion and plantarflexion during the BTT.ConclusionLong-term Tai Chi practitioners exhibited superior visuospatial ability and postural stability during goal-directed upper body movements, which was associated with sensitive proprioception and tactile sensation