NEUROMECHANICS OF SPECIFIC TRAINING SKILLS
AbstractINTRODUCTION Towing weights or parachutes, alternate leg bounds, bungee running, sprinting with weight jackets or sprinting against the resistance of a coach or a training partner are popular training exercises to combine the technomotorical elements of sprinting with strength training. It is thus assumed that these exercises are very specific. Training science states that specific training skills must only be applied to top athletes’ training routines, where general basic exercises do no longer show any adaptation effects. There is however no general agreement about criteria of specificity. The discussion is about the correspondence of training skills as mentioned above and the technomotorical ideal of sprinting. Can the load applied to the athlete within one exercise be so high that the skill can no longer be called specific? Is there a threshold between specific and unspecific? METHODS Several studies were conducted to yield insight into the subject. In a longitudinal study we focussed our interest on the adaptive effects of tow sprinting against various resistances. Tow sprinting was also investigated kinematically and analysed for differences to free and supramaximum sprinting. Tow sprinting against different resistances, sprinting with a weight jacket and alternate leg bounds have also been studied with respect to their muscle activation and the influence of the exercises to the innervation patterns. Those exercises have been analysed kinematically as well. Again they were also related to the sprint movements of the respective test subjects. Additional registration of muscle activity was assumed to reveal not only the effects but also the causes of technical alterations of running style due to the different load situation in tow running and other sa called specific skills such as alternate leg bounds and sprinting with a weight jacket. The main accelerating muscle were examined, i.e.: m.gastrocnemius, m.rectus femoris, m.biceps femoris, m.gluteus maximus, m.vastus medialis. RESULTS The training experiment revealed the strength training potential of tow running against high loads for especially the leg extensors. Differences to the control group have been highly significant. Kinematical analyses revealed a good correspondence of tow running to free sprinting though it was remarkable that even low loads altered running style considerably. Running against the resistance of a parachute showed highest correspondence to free sprinting whereas tow running with an added load of 30kg could in no case be regarded as a specific training skill. Still it was hard to distinguish objectively between specific and unspecific movements. No criteria could be found to determine a specificity threshold. The combined EMG and kinematic movement analysis revealed the severe disturbances of the free sprint movement patterns combined with the different load situations. Tow running not increases the electrical activity but also influences individual intermuscular coordination patterns. Increasing load alters coordination until it no longer corresponds to the free running action. In the case when hip extensors and knee flexors do no longer contribute to the forward acceleration of the body the exercises cannot be called specific. Then they are alternative exercises within strength training. REFERENCES Clarys,J.P./Cabri, J. (1992): Electromyography and the study of sports movements: A review. Brussels. bicker, A.(1995): Untersuchungen zur bereinstirnmung von Zugwiderstandslaufen und Sprintbewegungen. In Stein, N./Miide, U.: Widerstandsbelastungen im Schnelligkeitstraining. Koln Mero, AdKomi, P. (1987): Electromyographic activity in sprinting at speeds ranging from sub-maximal to supramaximal. Med. & sci. in sports and exercise.
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