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High Technology in Athletic Training and Performance Analysis

By

Gideon Ariel, Ph.D.

When they talk about their personal goals in sports, athletes usually say they would like to do their best, meaning, reach their maximum performance ability. It is a matter of achieving their absolute liimit in speed, strength, endurance, and skill and combining these elements with performance.

Different athletic performances can be likened to a spectrum. On one side of the spectrum are esthetic events such as gymnastics, diving, and figure skating where success depends on the ability of the athlete to create movements that are pleasing to the referees. In the midddle of the spectrum arre the endurance activities for which the athlete tries to maintain muscular contractions for long periods of time at submaximal intensity levels. And the explosive activities such as printing, jumping and throwing, where the athlete try to achieve maximal coordinate power.

Biomechanical analysis allows investigation of the particular event in order tocreate theideal model of performance. Analysis of the performer and subsequent comparison with the ideal model occurs to allow immediate feedback to the athlete concerning the deviation from the optimum.

The hardware-Software combination allow to model the human body as a sereies of moving "links" upon which muscular gravitational, inertial, and reaction forces are applied. The physical and mathematical model for such a system, although complex, is well defined. The system provides a means of measurring human motion based on the processing of video recordings of a subject's performance. This technique demonstrates significant advantages since it is non-invasive. No wires, sensors, or markers are needed to be attached to the subject (thoough markers can be used with automatic digitizing). In fact, the subject need not be aware that data are being collected. The present system is portable utilizing 2 Kg. notebook computer. Camerase can be taken to the location of the activity and positioned in any convenient manner, so as not to interfere with the subject .

A typical performance analysis assessment consists of four distinct phases - data collection, digitizing, computation, and presentation of results. Video recordings of an activity aremade using two or more cameras, stationary or panned. In the digitizing process two methods can be used. Visual digitizing and Automatic digitizing. The Automatic process require reflective markers to be placed on the athlete's joint center.

After digitization, the computation phase of analysis is performed to compute the true three dimensional image space coordinates of the subject's body joints from the two-diensional digitized coordinates of each camers's view. Computaton is performed using a direct linear transformation or the newer and more powerfull Physical Parameters Transformation, to determined the true image space locations in 3-D.

When transformation is complete, a smoothing or filtering prcedure is performed on the image coordinates to mremove small, random digitizing errors and to compute body joint velocities and acceleratons. At the completion of smoothing, the true three-dimensional body joint displacements, velocities, and accelerations have been computed on a continuous basis throughout the duration of the sequence.

At this point, optional kinetic calculations may be performed to complete the computation phase. Body joint displacements, velocities and accelerations are combined with body segment massdistribution to compute dynamic forces and moments at each of the body joints. Muscular contribution to these forces and moments can then be computed by selectively removing the inertial and ravitational kinetic components.

The presentation phase of analysis allows computed results to be viewed and recorded in a number ofdifferent formats. Body position and body motion can bepresented in both still frame and animated "stick figure" format in three dimensions. Results are reported graphically. Plots of body joints and segments, linear and angular displacements, velocities, acceleration, forces and moments can be produced in a number of format optons.

The preceding discusson has illustrated the use of movement analysis to assess functional capacity. However, functional capacity can also be measured directly by resistive dynamomenty devices. The system employ computerized feedback control of both resistance and movement during training exercise. The intelligent dynamometer allows the machine to dynamically adapt to the activity being performed rather than the traditional approach of modifying the activity to conform to the limitations of the machine.

Case studies in applied biomechanics demonstrate the importance of considering th true patterns of motion in determining efficient performance. One of the most important parameter in training is the ability to allow the performer to achieve a movement pattern of resistance or the pattern of motion experienced by the user during the actual activity. Then the ability to modify the pattern by re program the dynamometer. The standard isokinetic equipment cannot achieve these requirements.

The value of applying the principles of biomechanics to the assessment of functional performance has been clearly demonstated. Movement analysis provides the means to quantify human activity and to provide insight into the mechanisms that contribute either to superior or inferior levels of performance. In addition, a technology has been presented that permits exercise and rehabilitation patterns to biomechanically duplicate the target activity as measure of function capacity.



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