DETERMINATION OF ARMS AND LEGS CONTRIBUTION TO PROPULSION AND PERCENTAGE OF COORDINATION IN BREASTSTROKE SWIM

In the present study, the Indirect Measurement of Active Drag (IMAD) was used to study the contribution of the legs and arms to propulsion in breaststroke swim. Contrary to the Measuring of Active Drag (MAD) system, the IMAD can be used for all strokes and therefore enabled us to study the breaststroke swim to estimate not only the percentage of legs and arms contribution to propulsion but also the percentage of swimmers’ arms and legs co- ordinations. The method revealed that the best coordination was 87.8% and that the contributions of arms and legs in propulsive force were 67% and 65% and in velocities were 97.7% and 98.2%, respectively, showing that the swimmers received equal contributions from the arms and legs in propulsion and velocity during breaststroke swim

A COMPUTER SIMULATION FOR LEG STIFFNESS IN MAXIMAL SPRINTING

When humans and other mammals run, the body's complex system of muscle, tendon and ligament behave like spring. A computer simulation for terrestrial running at maximal speed is presented in this study, based on a leg with the properties of non-linear spring. At maximal speed, the horizontal speed has 'been conSidered constant while the vertical component was considered zero at landing. Three non-linear springs have been considered for quadriceps, hamstring, and gastrocnemius muscles with different stiffness coefficients. The goal of present study was to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when the sprinter alters the landing angles (from braking to take-off) at maximal speed. Results also showed that at maximal speed the stiffness coeffiCients presented non-linear behaviour

A MECHANICAL MODEL TO ESTIMATE LEGS MUSCLE STIFFNESS COEFFICIENTS IN HORSE DURING JUMPING

The purpose of present study was to use a simple mechanical model to estimate horses’ legs muscles stiffness coefficients in jump height during jumping a spread fenceof 140 cm high. A digital camcoder was used (25 Hz) along with Ulead Studio program in order to obtain time, related distance, and various angles in horses’ legs data. The total jump distance and time of flight for each horse were measured with a precision of 10^-2 m and 10^-2 s respectively. Biomechanical formulae have been established in order to evaluate the muscles stiffness coefficients. Three groups of leg muscles; serratus ventralis, biceps brachii, and radial carpal extensor were considered in this study and their stiffness coefficients were successfully estimated

A NEW BIOMECHANICAL APPROACH TO SIDE-FOOT SOCCER SHOTS’ CHARACTERISTICS DETERMINATION

This study considers the biomechanical factors that are relevant to succeed in the kicking of a ball into three points; A, B, and C pre-selected in the area of gate. Sixteen amateur of top university players participated in this study. Two cameras at 30 Hz were used in sagital and frontal planes. The recorded data were processed through computer with Ulead Video Studio and AutoCad softwares. The time of flight, time of ball contact with kicking foot, the angle of volley, ball velocity, and the angle of knee flexion were achieved. Then by biomechanical formulae, ball speed, launch angle, range, force exerted to ball, and finally the torques applied to leg joints; ankle, knee, and hip were obtained. The ball speed, launch angle, and the ball range were theoretically estimated and then verified with the mentioned method

DRAG FORCE RELATED TO BODY DIMENSIONS IN FRONT CRAWL SWIMMING

So far, a great deal of attention has been given to find out relationship between body dimensions (anthropometrical variables) and hydrodynamic resistance for actively swimming subjects. The development of a new indirect method for determining active drag (IMAD) warranted a reevaluation of this relationship, which was the aim of present study. Twenty one novice male swimmers with different body shape and experience ranging from 11 to 14 years and in mass from 35 to 70 kg have volunteered in this study. The variables were mass, height, upper limit length, arm, forearm, hand lengths, and torso, arm, and head circumferences. Very high and significant correlations were found between active drag and anthropometric variables. The drag force was ranging from 14.5 to 52.5 N. The results achieved from this study agreed well with the results obtained by other researchers using direct measurement systems

NINTENDO WII CONTRIBUTION TO SPORTS BIOMECHANICS: A PILOT STUDY OF PUSH-OFF KINEMATICS IN BREASTSTROKE SWIM TURN

WII, as accelerometer was used to study push-off phase in breaststroke swim turn. The accelerometer could not be used directly into the water; therefore necessary modifications had to be done in order to use it in water. The results have been compared with the results of Qualisys Motion Analyzer system and theoretical modelling. A comparison of three results showed that the Nintendo WII acceleration power was 0.978 (r=0.989) very near the theoretical one (r=1), while the digitized filming showed a poorer power of 0.443 (r=0.67).The main problem with WII system was the noise that in our pilot study was not properly coped. The results obtained were reasonable and opened a new window for the use of Nintendo WII system in future research

Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning