ENERGY EXPENDITURE DURING RUNNING CALCULATED FROM CINEMATOGRAPHIC DATA

This paper outlines a method of measuring energy expenditure and presents experimental results in horizontal running. Unlike research and experiments in the past decade whereby the energy expenditure was calculated based on oxygen intake and with athletes directly connected to equipment in the laboratory (e.g. Howley, E.T. and Glover, M.E. (1974); Morgan, D.W. eta1 (1989), measurement can now be undertaken independent of such a procedure. Our method involves filming and computer processing combined with anthropometric data. It is similar to the method of Aleshinsky's (1986), with the difference that we use the full 3D approach instead of being restricted to a planar motion. First we obtain cinematographic data (coordinates) of 18 landmarks of the human body by using 3 video cameras (50 Hz PAL system) and a Peak Performance system. A conversion software is used to translate these coordinates into Euler angles and base coordinates. It also calculates for each parameter a spline of the 5th order which serves as input for the next step. With the help of the commercial software SDS of Solid Dynamics, France, we animated a mathematical model (Hanavan model with segments based on anthropometric data of the athlete) according to movements in the film. Eight male sports students were filmed individually running at a speed of 4 to 5mls. In addition, four ran at a speed of 8 to 9mls. In each run a complete stride-circle was analyzed. Results of our calculations agreed with those given by the researchers who used the energy expenditure values reported by researchers who used the oxygen-intake method. At the lower speed, power per kg body mass was equal to 13.6 W/kg(v=4 m/s) and 17.0 W/kg(v=5 m/s), whereas the oxygen-intake method (corrected for oxygen consumption when standing quietly) yielded results of 14.7 and 18.5 W/kg. In addition, we were able to measure that the higher speed and the results revealed a dramatic increase of the power from 28 to 43 W/kg. In conclusion our method not only opens up the possibility of on-the-spot measurements for general motion (no restriction to aerobic movements), but that energy expenditure can be given as a function of time

THE INFLUENCE OF TIMING IN MOVEMENT EFFICIENCY

INTRODUCTION The vertical movement of the human body is visible in almost all sports. Even in the case of sports like running, cycling, and long jumping where the aim is to achieve horizontal distance, vertical motion is obvious and highly essential in performing the movement. Components of vertical motion contribute to the total energy needed for the movement. In this study we analyze efficiency of the vertical motion components and discuss timing as one of the factors influencing the energy consumption of the movement. Efficiency is defined as the quotient of the work output divided by the energy needed to perform and given as η= Wout / Ein where Wout is work per formed on a mass. In both the ascending or descending motions. Ein is energy produced by muscles to do so. In classical mechanics efficiency is calculated as positive for ascent and negative for descent. METHOD A computer simulation of human motion beginning in a standing position, moving down to a squatting position and vice versa was performed. The motion was constructed symmetrically for upward and downward movements, so that a downward movement can be described as an upward movement with time reversed (t -> -t). For this simulation we used the commercial software SDS Version 3.5 of Solid Dynamics. The human body is approximated by the Hanavan model using anthropometric data of a male person. Similar simulations are also done in the following movements: a) raising the body off the ground with one leg on a bench b) alternate stepping with one leg then the other, keeping the same foot position when on the ground C) lifting weights with the arms flexed In the second stage of the study we obtained real movement data using 3 cameras and a 3D Peak Performance digitizing system. This data and the anthropometry of our subjects were included into an inverse dynamics analysis, using SDS to calculate the efficiency. RESULTS Figure 1 represents the efficiency simulation for a squatting motion at difference timings. The graph shows for a downward or upward movement with a duration of 0.75 seconds, which result in an efficiency of 0.674. For slower movements η Coverges below 0.9. Our experiment shows efficiencies in the same range as the simulation. A detailed analysis of the various simulations demonstrates that efficiency is dependent on timing. Conclusion The above results suggest that the optimizing of efficiency helps to reduce energy consumption of the vertical motion. This subsequently provides more energy needed for the horizontal motion and thus the complete performance. Such effects seem unimportant for a single movement, but with thousands of repetitions in a cyclic motion the minute energy conservation adds up to a substantial amount and consequently influences the performance

THE ROTATIONAL ABILITY OF 'THE HUMAN BODY

In sports like gymnastics, trampolining and diving, attention is focussed on control and good execution. Like all general movements, the movements involved in such sports are motions that consist of translation and rotation. However in this case, proficiency depends dominantly on the rotational ability of the athlete while performing the movement. We analyze such a movement using parameters from anthropometry, dynamics, and posture. We recorded anthropometric data of top athletes in trampolining and compared them with those of ordinary people. With a computer program based on the Hanavan model together with mass density values given by Dempster, we use the data to calculate the inertia tensor. Further data pertaining to dynamics, timing and coordination are derived by video-cinematographic methods. With the aid of two cameras, we filmed simultaneously various trampoline performances during the international competition held in Dillenburg, Germany in 1991. The videos were then digitized and the data processed by computer. We obtain the results for momentum, body orientation, posture and the center of gravity of the trampolinists during a jump. We demonstrate how strongly body structure, dynamics, timing and coordination contribute to the ability of the human body to rotate. The important parameters are the inertia tensor and the momentum, the combination of which determines the rotating. While momentum remains constant during a jump, the inertia tensor may vary in time due to different postures. Our findings show what momentum is necessary and which posture have to be in sequence for athletes to excel

Initiation of a stable convective hydroclimatic regime in Central America circa 9000 years BP

Many Holocene hydroclimate records show rainfall changes that vary with local orbital insolation. However, some tropical regions display rainfall evolution that differs from gradual precessional pacing, suggesting that direct rainfall forcing effects were predominantly driven by sea-surface temperature thresholds or inter-ocean temperature gradients. Here we present a 12,000 yr continuous U/Th-dated precipitation record from a Guatemalan speleothem showing that Central American rainfall increased within a 2000 yr period from a persistently dry state to an active convective regime at 9000 yr BP and has remained strong thereafter. Our data suggest that the Holocene evolution of Central American rainfall was driven by exceeding a temperature threshold in the nearby tropical oceans. The sensitivity of this region to slow changes in radiative forcing is thus strongly mediated by internal dynamics acting on much faster time scales

International Society of Biomechanics in Sport March Newsletter 2015

IN THIS ISSUE: Message from the Editor, Preview of ISBS 2015, Poitiers, ISBS Student Mentor Program 2015,ISBS Student Mini Research Grant, ISBS Student Development Profile, Call for ISBS Awards, Hans Gros Emerging Researcher 2015, ISBS Practitioner Profile, ISBS Membership Renewal, Call for bids for hosting ISBS, ISBS Lab Profile, Call for ISBS Election, ISBS Sponsors, ISBS Officer

Parasitic Nematodes Modulate PIN-Mediated Auxin Transport to Facilitate Infection

Plant-parasitic nematodes are destructive plant pathogens that cause significant yield losses. They induce highly specialized feeding sites (NFS) in infected plant roots from which they withdraw nutrients. In order to establish these NFS, it is thought that the nematodes manipulate the molecular and physiological pathways of their hosts. Evidence is accumulating that the plant signalling molecule auxin is involved in the initiation and development of the feeding sites of sedentary plant-parasitic nematodes. Intercellular transport of auxin is essential for various aspects of plant growth and development. Here, we analysed the spatial and temporal expression of PIN auxin transporters during the early events of NFS establishment using promoter-GUS/GFP fusion lines. Additionally, single and double pin mutants were used in infection studies to analyse the role of the different PIN proteins during cyst nematode infection. Based on our results, we postulate a model in which PIN1-mediated auxin transport is needed to deliver auxin to the initial syncytial cell, whereas PIN3 and PIN4 distribute the accumulated auxin laterally and are involved in the radial expansion of the NFS. Our data demonstrate that cyst nematodes are able to hijack the auxin distribution network in order to facilitate the infection process

Linkage scan of nicotine dependence in the University of California, San Francisco (UCSF) Family Alcoholism Study

Nicotine dependence has been shown to represent a heritable condition, and several research groups have performed linkage analysis to identify genomic regions influencing this disorder though only a limited number of the findings have been replicated

Construction of a consistent YAC contig for human chromosome region 3p14.1

Chromosomal deletions and translocations of human chromosome region 3p14 are observed in various human malignancies and suggest the existence of a tumor suppressor gene locus within this region. Tumors most frequently affected by these aberrations are small-cell lung cancer and renal-cell carcinoma. In continuation of our previously published YAC contig of chromosome region 3p14.2-p14.3, we report here on the construction of a YAC contig of at least 11 Mb that consisted of 171 YACs and covers the entire subregion 3p14.1. This contig includes the t(3;8) breakpoint of a hereditary renal-cell carcinoma localized in 3p14.2 and extends into human chromosome region 3p12-p13. It defines the order of 34 DNA probes in relation to reference markers D3S6 and D3S30 as well as the human protein tyrosine phosphatase-gamma gene. For 31 DNA probes we identified nonchimeric YACs by fluorescence in situ hybridization. The minimal tiling pathway consists of 16 yeast artificial chromosomes. As a prerequisite for identification of a putative tumor suppressor gene within this region, this contig renders human chromosome region 3p14.1 accessible to gene isolation