EVALUATION OF TRAINING METHODS BY MEANS OF KINEMATIC MEASUREMENTS

Abstract

INTRODUCTIONAim of this work is the evaluation of different training techniques developed for increasing the hip joint range of motion.The standard technique has been comparedwith a training program based on PNF(Proprioceptive Neuromuscolar Facilitation).The experimental data were acquired by using an electrogoniometer system for its easy application in sport exercices, for its reduced dimensions and weight and for its high sample rate (up to 1000 Hz).The quality of the results has been critically analysed and compared with experimental tests made by using both electrogoniometer and optoelectronic system. MATERIAL AND METHODS The flexion extension movement of hip joint of101 male volunteer students, aged between19 and 23 years, was evaluated before and after a training with PNF. The subjects, fastened to an experimental table in supine position, were asked top erform the maximum hip flexion. The tests consist also on passive movements. Preliminary 'results seem to confirm the adequacy of the training technique but the high dispersion of the results leads the authors to analyse the possible causes related to the phenomena. With this aim further tests have been acquired both with electrogoniometer and with an automated optoelectronic system. The experimental analysis included both planar motion of two hinged bar and athletes movement during the standard test. For these analysis reflective markers where rigidly fixed on the electrogonio meter bases. From the 3Dmarker coordinates the angle (a*) between the electrogoniometer bases has been evaluated and compared with that one obtained by the electrogoniometer output. RESULTS The results of the training program showed that the range of motion of the subjects increases after the PNF technique both for passive and active movements The angle between the bases is evaluated in[1.11in which RCHA and RCHB are the electrogoniometer output data representing the two active channels, a and 8 the angles represented in Fig. I.Fig.I In the evaluation of athlete movements the analysis of the result differences of the two systems adopted leads to these following considerations. For the analysed movement the effect of the goniometer cable torsion seems to be negligible while an incorrect calibration procedure seems to be the main source of errors. In fact in the evaluation of athlete movement the gauges have been zeroed at the initial movement position and not with the basis perfectly aligned. This error can be easily corrected if the relative position of the bases is known by using the [ I .2]where k~ and k~ are the output of the electrogoniometer previously correctly calibrated and then placed on the subjects. Another source of errors may be due to the skin where the bases and consequently the markers are fixed. This effect can be partially solved by using rigid cluster linked to the moving body segment. CONCLUSION This study leads to consider new aspects of the movement evaluation by using electrogoniometer and suggest some practical rules to correct the electrogoniometer acquired data.