Innovative sensory-motor model conscious to movements based on simulation of mathematical modeling flywheel sprinting style

Фотографии: 

ˑ: 

V.G. Semenov1
Y.A. Maslovskiy2
V.I. Zakrevskiy3
T.P. Yushkevich4
1Smolensk State Academy of Physical Culture, Sport and Tourism, Smolensk, Russia
2 Polessky State University, Pinsk, Belarus
3Mogilev State A.A. Kuleshov University, Mogilev, Belarus
4Belarusian State University of Physical Culture, Minsk, Belarus

Keywords: run stride structure; sensorimotor model; movement apprehension model; mathematic simulation; sensorimotor sensitivity; muscle activity profiles by run phases; stride style of sprint run; foot phalanges zone; purposely controlled subject environment; body flexor/ extensor muscle strength complex

Introduction

It is in the course of the ongoing innovation process that special efforts are being taken to rethink the new evidence that supports the idea of strength symbiosis of the flexor and extensor muscles and their realignment on the internal, inter-segmental and integral levels of the lower limbs within the frame of the sprint run biodynamical model to help develop and excel the linear speed qualities of female sprint runners (V.G. Semenov, 1997, 2008).

The purpose of the study was to provide an experimental evidence to support the innovative sensorimotor movement apprehension model based on mathematical simulations of stride style in sprint run.

Materials and methods. We have developed a promising method of theoretical synthesis of competitive sport techniques based on human body movement simulation model using the relevant application computer tools (V.I. Zakrevskiy, 2007). The core idea of the method is to decode the multi-component biomechanics of the competitive movement sequence in terms of space and time and describe it by the second-degree differential equations on the whole and the second-degree Lagrange equations in particular. The sprinter’s biomechanical system movement synthesizing equations that refer to the aerial (unsupported) phase of the run sequence are designed based on the relevant mathematical model; since these equations have recurrent structure and apply to the N-segment model, they provided us with the means to computerize the movement generation process. It was based on this mathematical model that we studied the stride style of sprint run using preset space- and time-specific parameters. We used the 100 m sprint race video captures of six elite men sprint runners for our video-cyclographic analyses. We used the formula offered by V.I. Zakrevskiy (2007) for the mathematical profiling of the aerial phase of the runner’s movement sequence. In applying the formula, we assumed the kinematic scheme of the N-segment biomechanical system acting on the condition of the athlete having no contact with support, i.e. the movement model mathematical design method applied to a free three-segment structure.

Results and discussion. The study results demonstrated the important role of the stride movements as verified by the muscle activity profiles decoding (I.M. Kozlov and L.V. Samsonova, 1990) and the mathematic simulation (V.I. Zakrevskiy, Y.A. Maslovskiy, 2007) data.

These findings gave us the means to objectively consider the dominance of the sensorimotor sensitivity in the phased activity profiles of the muscle groups with the emphasis on the proximal flexor muscle action sequence and its work mode in application to the lower limbs of the modern elite sprint runners (Y.A. Maslovskiy, 2005).

Furthermore, it was found by the study that the movement control in every stride was 90% exercised with no controlling contribution from brain cortex, and only some 10% of the run movements were apprehended, including the leg stride movements (V.D. Kryazhev, 2002). Therefore, there are good grounds to state that the whole stride action within the run step sequence comprises an ideal and accessible movement apprehension model. It is known that N.A. Bernstein (1947) described this type of functional process as the “ancient musculoskeletal impulse pushing the leg forward”, with the relevant run technique element being called the “active stride”. The striding action is intended to drive the lower limbs and the body centre of gravity (BCG) in the aerial movement phase. This is how the athlete really controls the movements in the striding leg carry-over phase for account of the internal forces generated by thigh flexing and extension action that involves thigh flexor muscles (including musculus iliopsoas, musculus Sartorius, wide fascia stretcher, and crested and straight muscles), reactive force generated by the thigh acceleration and retardation actions in the movement phase, and inertial force. As demonstrated by the study data, the run speed loss values were the lowest in the moment of the support leg being cushioned in the ankle joint. The follow-up motion of the striding leg goes on in the back step phase, while the maximum cross movement of the legs occurs in the aerial phase of the movement sequence (V.I. Zakrevskiy, Y.A. Maslovskiy, 2005).

The stride phase of the run claims higher contribution from the pelvis rotation movements around the longitudinal and sagittal axes, with the pelvis rotation angles coming up to 40-45º. The maximum bent of the pelvis is registered around the sagittal axis at the moments when it comes to the vertical position. It should be emphasized that trunk movements make a significant contribution to the stride style of the run technique. Growing intensity of the trunk movements along the longitudinal axis are found to contribute around 6-10% to the speed of the run in fact.

It was further found by the biomechanical analysis of the run technique movement sequences of the leading modern elite sprinters, as demonstrated by the sets of qualitative and quantitative indicators, that the back step and pelvis movement phases are driven mostly by extensions of the thigh flexor muscles and for this reason are extremely efficient. In the front stop phase, when the leg goes down to the ground, the striding movements are driven by the thigh and trunk extensor muscle groups, with the potential energy being transformed to the kinematic energy and, hence, the linear speed of the run and BCG being kept up. Consequently, the efficient striding movements in the high-speed musculoskeletal sequences help move the body and contribute to the BCG being accelerated, and thereby increase the strength impulse of the foot pushing off the ground (D.D. Donskoy, 1985).

Therefore, it may be stated with confidence that the most effective stride style model is the one that is typical for the modern elite sprinters’ run technique. The study further demonstrates that the foot-and-ground contact is controlled by the foot phalanges zone with the leg being bent to the maximum in the knee and hip joints as this technique helps the aerial and ground phases of every stride being combined in a most efficient manner and, for this reason, the free limb segment movement frequencies may reach their maximums. This stride style performance manner significantly increases the workloads on the trunk and thigh extensor and flexor muscle groups; and this is why they must be functionally fit for the run, with the top fitness being developed by the special new-generation tools and training equipment. Therefore, the strength integrity of the trunk extensor and flexor muscles plays not only the role of an upper support to absorb the eccentric push-off reaction, but, more importantly, transforms the inertial and reactive forces into the motor actions of the lower limbs. The upper part of the body (including arms, shoulders and trunk) effectively takes in the eccentric push-off reaction by moving in the opposite direction. In this motor element, the right arm and shoulder move forward or backward together with the left leg, whilst the left arm and shoulder move together with the right leg. The step frequency rates, however, are so high in sprint run (up to 4.8 to 4.88 steps per second for women and 5.0 to 5.5 steps per second for men) that it is practically impossible for the shoulder “twist-untwist” movements (restricted by the natural compensatory frame) to take in the frequent and powerful push-off reactions of that kind in every run cycle. There are good reasons to believe that it is the arms that “lead” legs in the sprint run process and, since the actions and counteractions are interrelated, fast and strong arm movements may help reinforce the lower limb movements, including the push-off actions (D.D. Donskoy, 1985).

This gives us the grounds to state that the stride energy zone expands and part of the sprint workload is taken over by the relevant trunk muscle groups acting as an upper functional support. It may be maintained in this context that the run musculoskeletal movement design with the high contribution of the stride style to support and reinforce the linear speed of every body segment helps generate distinctive energy “waves” by the striding motions of the right and left legs with the active contribution of the relevant trunk muscle groups. The energy waves travel, in an asymmetric manner, both along and in between the lower and upper elements of the sprinters’ musculoskeletal system, with the wave rhythms being synchronized by the system elements in terms of the wave amplitudes and frequencies that is characteristic, first of all, of the increased contribution of reactive forces (D.D. Donskoy, 1995).

The run stride style helps shape up the relevant functional geometry of the lower limb muscle groups that creates an important framework to support, facilitate and increase the movement sequence frequency characteristics to the maximum possible degrees. On the whole, this bodily geometry helps increase the movement speeds of the lower limbs in every run step through convergence (harmonization) of the extensor and flexor muscle group actions in the thighs, shins and feet (V.G. Semenov, 1997, 2008).

In view of the high importance of the reactive forces in the run technique, let us consider them in more detail. As found by some sport researchers (L.V. Chkhaidze, S.M. Chumakov, 1972) , there are reactive forces acting as reflection of the main forces and originating in peripheral zones of the musculoskeletal system of an athlete. It is a matter of common knowledge that a prime objective of the run technique being performed in a most efficient manner is to suppress every excessive negative force so as to free up only those forces that contribute to the necessary functionality of the most efficient running techniques and motor actions; and since the case under consideration is no exclusion, these negative forces need to be neutralized too. However, a sprint run technique always generates reactive inertial forces designed to correct motor actions by impulses from the CNS control mechanism. Impulses of such forces are always generated in the moments when the run movement is in the need of apprehensive correction of the striding action that happens when the lower limbs are in the aerial phase of the sequence. Therefore, the main objective of any run movement control function is to control the reactive forces to make them contribute to the efficiency of the run motor sequence performance, with their potential negative effects being mitigated.

It may be assumed that the process of the striding leg being carried over by the acceleration wave in the run motor sequence comprises an ideal functional model of apprehended motor actions. As stated in one of the I.M. Sechenov’s studies, a movement control mechanism may be in effect reduced to permanent, subordinated and strict corrective impulses coming from the CNS. These corrective impulses come to the brain cortex which analyses, apprehends and corrects them based on the data coming from the peripheral systems. To put it in other words, the CNS issues a command to trigger the movement by activation of the relevant muscle groups and thereby controls the motor sequences of the body segment, with the body centre of gravity (BCG) being accelerated and the muscle strength gradients applied to the push-off-ground actions being increased (D.D. Donskoy, 1985).

Therefore, we should recognize that the most efficient stride style model is the one that (as demonstrated by our studies) is typical for modern elite sprinters; this motor action model in this case is found to be subject to uninterrupted control and natural corrective actions of the relevant muscle groups. It was N.A. Bernstein (1947) who demonstrated in his theoretical and experimental studies that the most important force-initiating impulses are generated in the moments when the subject motor sequence is in the most urgent need of corrective actions (in the starting moment of limb stride or leg carrying action, for instance). In this case the author considers the permanent sensor correction that fits into the motor action control cycling theory that assumes the corrections being apprehended. It is on this theoretical basis that N.A. Bernstein established his assumption that the muscular actions and the resultant movements of the body segments are generally interacted in the sense that they act on one another on a permanent basis. This assumption was substantiated by the relevant mathematical proof (in the form of differential equation) of the cyclic nature of the motor sequence control mechanism subject to apprehended movement control. Furthermore, studies by M. Feldenkrais (2007) demonstrated the high priority and critical importance of the movement apprehension mechanisms in the context of the body-perfection-focused personal development systems. These systems consider a human body and mind as the integral system and non-interrupted mental-and-physical process, with every change at one system/ process level immediately triggering the relevant effects at the other levels. These systems are focused on the ties in between the movement control segments of the brain cortex and the muscles; and assume that the human body is able to move with the minimum efforts and maximum effectiveness due to not only the increased strength application actions but to the increased awareness and apprehension of the movement sequence.

Findings of the study convincingly demonstrate that the stride style of sprint run is geared to mobilize the inertial and reactive forces and apply them in a most efficient manner in the aerial free-limb phase of the musculoskeletal system movement sequence. It was further confirmed by the set of laboratory tests that this run style is both the most apprehended and the best controlled run style in use by elite athletes.

Conclusion. The relevant specific motor objectives – with the top priority being given to the stride movements in the sprint run as the largest contributors and controllers of the maximum pace and, consequently, increased linear speed – are attainable only based on application of designated sensorimotor and biotechnological tools that may be implemented in conditions of “purposely controlled subject environment”.

References

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Corresponding author: usacheva-s@bk.ru