bernstein's stages of motor learningbernstein's stages of motor learning

Bernstein was one of the pioneers in the field of motor control and motor learning inventing original devices that track the motion of people with and without experience in actions. Bernstein was one of the pioneers in the field of motor control and motor learning inventing original devices that track the motion of people with and without experience in actions. Keep in mind that just like too little variability (rigidity) is not optimal too much variability (aka instability) is also not optimal. Movement and postural variability, as discussed previously, is also proving to be an extremely cost effective strategy in reducing the incidence of repetitive stress problems as is seen with too little variability (aka rigidity). Furthermore, the number of muscles acting across a joint generally exceeds the number of kinematic degrees of freedom of that joint. Would you like email updates of new search results? These questions are what eventually lead me to the Chinese martial arts and getting certified as a mobility specialist according to Dr. Andreo Spina and Functional Range Conditioning (FRCms).For me, one of the takeaway from the dynamic systems theory: The biomechanical system can be seen as a sensory filtering mechanism which can be polished via mobility training. FOIA Bethesda, MD 20894, Web Policies As a result, a given movement can be realized with an infinite number of muscle activation patterns (also referred to as the 'inverse dynamics problem'). ), Motor development in children: Aspects of coordination and control (pp. If you can underpin your training with theory from motor learning you will likely be able to understand why a specific training is useful and be able to refine your practice structure. In rehabilitation, we are conditioned to have our patients and clients move slowly in order to be safe, which is wise in the early phases of an injury. So the original motor command is allowed to play out which could lead to either missing the ball completely, missing the goal, a terrible pass, or an injury. It seems that, once again, variability plays a key role in the health of our movement system, similar to the correlation between the neuro-cardiac biomarker of Heart rate Variability (HRV) and our adaptability to stress. The outcome of the movement (i.e. For example after going through a Tai Chi movement, we might then go to a normal or faster speed that might seem normal and then immediately go back to very slow. Many researchers allude to this as the movement strategy. Note here, however, that Bernsteins theory is not a hierarchy, but a continuous perceptual motor interaction. Other tasks, such as dribbling in Football (and other open skills), require sportsmen and women to be able to adapt their movement in order to be successful, as multiple ways of dribbling (movement patterns) are often useful. Think about post-ACL reconstruction where the ACL is back, but now it is about teaching it how to function with the rest of the body in different conditions. Thus in the recent years there seemed to have been an unnecessary shift away from respecting isolated parts given the seductive nature of whole movement patterns. Wouldnt it also make sense if these synergies were controlled by subcortical areas of the CNS, reflex motor control, to allow our conscious mind to focus on other tasks? Their score in this test is our measure of motor learning. Bernstein's levels of movement construction: A contemporary perspective. Moreover, control parameters like direction, force, speed, and perceptual information are variables that move the learner into the new attractor state. 2020 Jul 30;24(4):512-526. doi: 10.1123/mc.2019-0118. So, as the image demonstrates, the question now becomes: Do we really need voltage coming from higher CNS descending tracts or could the voltage from ascending sensory afferents suffice? https://sportscienceinsider.com/author/will_shaw/. This way of looking at movement, may make the dynamic systems model more attractive to biomedical engineers compared to Physical Therapists, Chiropractors, Athletic Trainers, and Performance coaches. To paraphrase Berstein here, it is the characteristics of both the internal forces, musculoskeletal and neurological systems (along with the other systems), and the external forces: gravity, environment, and the task, that one must understand before really understanding the neural control of movement. The bottom line is to migrate away from the idea and the message of this position/posture/movement is bad for you and this one is good for you. I wish someone told me this before I unintentionally hurt those two clients with back pain. This stage is also called the motor stage (Adams, 1971) because the problem to be solved in the associative stage is learning how to perform the skill (Schmidt & Lee, 2005). Through our 4 week treatment plan we-re-taught Katie how to express flexion at her upper thoracic spine through various manual therapy and self care strategies. As an interdisciplinary science, skill acquisition engages experts in neuroscience, physiology, psychology, biomechanics, and coaching, as an avenue to research how the neuromuscular system functions to activate and coordinate the muscles and limbs involved in the performance of a motor skill. Latash ML. To begin with, movement requires a lot of conscious control and thought. This site needs JavaScript to work properly. 1st step. In these lines, to rhyme drowned and found, Coleridge inverts the standard word order: Wulf, G., & Lewthwaite, R. (2016). Remember back to our discussion of how variability from correct posture is seen as a mistake or an error from a motor program perspective. However, crucially, during this blue phase we still dont know how much motor learning has taken place. This denial leads to the thought of we just need to move because pain is just an output of the brain anyway. In Bersteins mind coordinating movement is the process of mastering the redundant degrees of freedom of the moving organism. He also believed that: You cant understand the neural control of movement without understanding the characteristics of the system you are moving and the internal and external forces acting on the body. (Bernstein, 1967). Just be sure to acknowledge that the concept of variability needs to still be anchored by the natural principles of biomechanics, tissue tolerance, progression, motor learning, and common sense. Browser Support. Thus when progressing a flexion intolerant spine back to weight training we can integrate variability while still utilizing the principles of biomechanical leverage andgood old-fashioned technique of lifting and strength training. The client is asked to strike a target that moves after each rep. The three distinct phases of learning include 1) the cognitive stage, 2) the associate (also called intermediate) stage and the 3) autonomous stage. He says that there are many schools of eastern martial arts and most of them are very strict with form and joint position in the early stages of their training. For example I once got to observe a track coach cuing up one of his athletes with phrases like, THROW your knees to the sky while driving your other foot through the earth! So although we're still confronting a load sensitive and flexion intolerant spine, we immediately plant the seed of how we're going to avoid these positions while maintaining productivity standards without demonizing flexion itself. I have intellectually and physically lost so many clients in the past because I inappropriately jumped into pain science education with central sensitization concepts before educating about tissue level peripheral sensitization. I have a bit of neck and trap tension now but it's nothing compared to what the back pain was before. From the cognitive perspective, the athlete is attempting to translate declarative knowledge into procedural knowledge. By using, inter alia, Bernstein's 24 English and German articles, the authors present an analysis of the development of Bernstein's theory of movement behavior, against the backdrop of the scientific progress in the Soviet Union in Bernstein's time and the clashes between Soviet politics and science. muscular, skeletal, neurological, and biological) has no commander, meaning the movement self-organizes. Although there may be some differences between the sport and the rehab situations because the patient was skilled prior to the stroke, in both cases you must approach skill acquisition from the perspective of the beginner. So contrary to popular belief as we get better at a motor task there seems to be more variability, not less, in the neuronal discharge patterns being recorded from the CNS. (2020) identified only 13 studies that have investigated freezing and freeing of degrees of freedom in motor learning. Brooks/Cole Pub. The purpose of the study was to optimize productivity, and Bernstein's analysis focused on cutting metal with a chisel. My Tai Chi Sifu (Master), offered me a refreshing perspective that helped me see movement variability in a new light while blending the other motor control models. While they share their similarities and differences, skill acquisition is much deeper than this. On the surface it seems like Spinas parts-focused approach contradicts many movement pattern based approaches (i.e FMS & PNF) out there. The movement pattern established becomes a generalised concept, neither consistent nor efficient. And if we have them sit with better posture and their pain goes away doesnt that indicate that were on to something? 2020 Jun 25;11:1295. doi: 10.3389/fpsyg.2020.01295. If a joint cant do what a movement pattern is requiring, then the system will self organize to move around the limitation. Federal government websites often end in .gov or .mil. Coordination of degrees of freedom and stabilization of task variables in a complex motor skill: expertise-related differences in cello bowing. These include affordances, attention, motivation, cognition, experience, and more. Think of degrees of freedom as the number of joints in the body (well over 300) multiplied by the sum of all of the available ranges of motion at each joint, which for most joints includes 3 planes of motion. bongaardt@svt.ntnu.no PMID: 11008272 DOI: 10.1080/00222890009601360 Abstract eCollection 2020. eCollection 2020. Disclaimer. All we can say with confidence is that input comes in, gets processed, and we get a movement behavioral output. Arajo, D., & Davids, K. (2011). ---task dependent, Week 10 - Stages and Transfer of Learning, AS PE Skill Acquisition - Learning & Performa, The Language of Composition: Reading, Writing, Rhetoric, Lawrence Scanlon, Renee H. Shea, Robin Dissin Aufses, Eric Hinderaker, James A. Henretta, Rebecca Edwards, Robert O. Self, John Lund, Paul S. Vickery, P. Scott Corbett, Todd Pfannestiel, Volker Janssen, Byron Almen, Dorothy Payne, Stefan Kostka. Motor learning has been defined by Shumway-Cook and Woollacott (2017, cited by Bisson) as the process of the acquisition and / or modification of skilled action. Lets reflect on how this motor program narrative and these word choices can lead to catastrophization and fear-avoidance behavior for Bob. This linear/biomechanical perspective is necessary and has served as a valuable tool in advancing our understanding of movement. HEY BRO! Eds. While Bernstein's stages - which emphasize learning from both a motor control and biomechanics perspective - have gathered popularity of late, this post will take a look at Fitts' learning theory as it's premise is based on perceptual factors.which are quite relevant when it comes to tennis. The only way to optimize the afferent inputs from these joints mechanoreceptors is to ensure a competent level of mobility because movement is what stimulates these proprioceptors (i.e mechanoreceptors). Relate this to the early stages of learning, quality coaching and mechanics, and proper delivery of feedback. The resting discomfort she was constantly feeling quickly dissipated. Smaller errors and better consistency is shown because the basic fundamentals have been established and are now being refined. Luckily for us, we also have the option of consciously controlling these three pillars of function. Although their approach start with appraising patterns, checking the parts is an integral part of both their systems (From my experienced as a resident in Vallejo, CA and an assistant instructor for the Selective Functional Movement Assessment). This system is set in its ways and essentially cant adapt to change because feedback isnt a part of the control process. Let us image we have a 18 year-old learning to throw a bean bag underarm into a basket placed 5 metres away with their non-dominant hand. As demonstrated above, we can still present a motor program / biomechanical model within the framework of both pain science and the dynamic systems model using the principle of variability as our guide. I saw both of these clients a couple of days later and the client who presented with mild nerve tension came back reporting full-blown sciatica just hours after our previous session. While all of them appear to share similarities, they differ in their own respective perspectives on how perception and action play a coupled role in skill acquisition, with Bernstein arguing that a motor skill is learned through solving a motor problem. With that in mind, another question Bernstein proposed was: How do the patterns and organization we see in nature come into being from odorless constituent parts?. Would you like email updates of new search results? The general framing of the model and the separate skill acquisition stages in young children are primarily based on two different concepts to approach the control of complex human behavior: The Degrees of Freedom (DOF) problem (also referred to as the motor equivalence problem) has been introduced by Bernstein (1967). Keep in mind that there is a sweet spot to variability.Too much variability is known as instability and too little variability is rigidity. If you are being chased by a rattlesnake, there will clearly be more muscle contraction than if you are running a lap around your local track. It was the Friday of Labor Day weekend early September in Boston back in 2014. Epub 2017 Sep 11. Modularity for Motor Control and Motor Learning. relative timing, relative force, sequence) which changes from situation to situation. This is a valid point however this rationale only considers the short term resolution of pain and does not take into account the longevity of the client and their musculoskeletal health. Motor Control. Knowledge of Results vs Knowledge of Performance, Skill Classification Continuums Learn the Basics, Fitts & Posner's Stages of Learning Cognitive, Associative & Autonomous, Performance Coaching & Skill Acquisition in Elite Golf, full article on the Cognitive, Associative & Autonomous stages of learning, How to Power Clean Guide Master Your Technique, The Power Snatch: How-To Guide, Benefits & Programming, Practice: Percentage of scored penalties in a football training session, Retention: Percentage of scored penalties in next weeks training, Transfer: Percentage of scored penalties in cup final after 120 minutes play. Newell KM, Carlton LG, Hancock PA. Another name for this stage is the motor stage. The message I kept reminding her was, Slumping is not the enemy, mindless stagnation of posture is. We have to realize that the majority of our clients have no clue or any reference regarding the abstract concepts of neuroscience like the smudging of the homunculus, the overriding fear-memory of the amygdala, and the CNS perception of threats influence on up-regulating peripheral receptors in the dorsal root ganglion. 107-109) identified and described a number of changes that occur with learning in humans and other species in a range of movement tasks. Keep in mind that this sensory feedback can encompass any of the sensory modalities (vision, auditory, beliefs/perceptions, mechanical/proprioceptive) as a means of communicating back to the control center to alter behavior. However with the dynamic systems model, the food menu can provide a very interesting variety of options allowing us to mix and match appetizers, entrees, and desserts to create a very different yet engaging dining experience with each visit. To facilitate this, the coach again needs to identify task variables, set key variable parameters, and induce contextual interference effects accordingly. Consider the following example: The example above highlights that athletes ability to retain and transfer their skill is more valuable than their practice performance. The field of motor control basically studies how the Central Nervous System (CNS) controls posture and movement. Our example data shows that retention scores are rarely as high as the peak during practice performance. They have 100 practice throws and we give them a point for each successful throw. The third stage in this model is the autonomous stage, where the skill has become automatic. No theory to date is perfect, however each does capture something useful that helps us understand how we learn movement. Gentiles two stage theory of motor learning places the performers goal at the centre of learning. Motor control is the study of how we control movement and produce useful coordinated responses. Harbourne RT, Stergiou N. Nonlinear analysis of the development of sitting postural control. Relate effective teaching and practice conditions to Bernstein's theory of Freezing the Degrees of Freedom. Of course, this is nothing but intuition and it needs to be further investigated especially within open skills. Fair warning this principle is one of the hardest to understand at first. Although there are rules in the english language, every word typically has a synonym which allows us to express what were thinking in various ways; this is the beauty and art of language. Latash and his colleagues, thus extrapolated on Bersteins idea of synergies and describe a synergy as a neural organization (not just muscles) of a multi-elemental system that: 1) Organizes sharing of a task among a set of elemental variables i.e higher order neurons, lower level neurons (motor units), muscles and joints and. We are sorry that this post was not useful for you! This is a very linear way of thinking about synergies. Thus, Spina suggests that we take a step back from obsessing over whole patterns before we have checked that the parts (joints) involved in the respective pattern are even communicating to the CNS in the first place. Bernstein figured that muscle synergies were a rational idea for solving the degrees of freedom problem. Motor learning theory sits at the heart of improving performance. Either way, you are still engaging in the motor skill of running, but with different task goals. Without this sensory feedback we would have something called an open loop system which looks like the image below. Schmidt [7] defines a motor program as an abstract representation of a movement plan, stored in memory, which contains all the motor commands required to carry out the intended action. Invariant features are relatively fixed, whereas parameters are flexible features that define how to execute the generalized motor program, easily modified from one athlete to another. Repetition without repetition as famously stated by Bernstein himself reminds us that no two movement patterns will ever be the same. 6, 8, 15-18 Two key theories which have influenced neurological physiotherapy are Bernstein's 'motor schema theory' 19 and Fitts and Posner's three key stages of motor learning. Step 2/2. However, as World War I broke out in the summer of 1914, the Bernstein family felt the need to help their country during these hard times. What characteristics of your performance changed and how did they change? Long story short she was very proud of the fact that she always has good posture and never catches herself slumping anymore. Dexterity and its development (M. L. Latash & M. T. Turvey, Eds.). Undoubtedly you thought about a number of things, such as how you held the racquet, how high you were tossing the ball, whether you were transferring your weight properly at contact, and so on. like talking on a phone, etc.). (2007). HHS Vulnerability Disclosure, Help It is, therefore, imperative that we further the dialogue, perhaps towards the ecological (i.e. We also share information about your use of our site with our social media, advertising and analytics partners. This new thought process of posture lines up well with the fact that variability is inherent in all biological systems to optimize health. The dynamic systems model offers a unique set of questions to ask ourselves before jumping to conclusions. Thus the three functional synergies that Berstein proposed that could solve the degrees of freedom problem: The use of these synergies could be a very reliable way to control the many degrees of freedom the body has to offer while providing an abundance of variations within these three synergies. He was born and died in Moscow. Keywords: skill acquisition, motor learning, motor control, movement science, generalized motor program, schema theory, movement variability, constraints, dynamical systems. The field of motor control basically studies how the Central Nervous System (CNS) controls posture and movement. This narrative demonstrates that with a dynamic systems mindset we don't have to give the direct message of right vs wrong or good vs bad. Self-learning becomes huge here because skilled performers can detect their own errors and make the proper adjustments. For example, in the picture on the far left we have a very constrained task. A On the line before the following verb, write PPP if the verb expresses physical action, MMM if it expresses mental action, or NNN if it expresses no action. They are [8] : According to Gentile's Model: There are 2 stages in this Model. It was a paradigm shift that resulted from a self care education lesson on posture. The other client had a 75% increase in back pain the night of our session. a volleyball serve mimics a baseball throw). It seems to me that the concept of synergy has been taken too far and out of context in recent years as there are many who have belittled the importance of screening, assessing, and treating isolated joints and muscles. The non-linear model also suggests that new behavior can emerge due to a critical change in one of the systems control parameters. Epub 2012 Oct 30. FOIA So I asked him why is it so important for you to keep your chest up like that? Jay responded Im trying not to slump because I was told that it wasnt good to slump.. 2022 May-Jun;30(3):325-341. doi: 10.1080/15438627.2021.1888104. Bernstein (1967, pp. Newell, K.M. 20 These theories have primarily evolved from . 2016;957:3-19. doi: 10.1007/978-3-319-47313-0_1. Cognitive perspective, the athlete is attempting to translate declarative knowledge into procedural knowledge and other species a..., skeletal, neurological, and biological ) has no commander, meaning the movement based... Bernstein & # x27 ; s model: there are 2 stages in this model is the process mastering. ( i.e FMS & PNF ) out there PA. Another name for this bernstein's stages of motor learning is the stage., relative force, sequence ) which changes from situation to situation its development ( M. L. &. Capture something useful that helps us understand how we learn movement that this post was not useful for!. Bernstein & # x27 ; s theory of motor control basically studies how the Central Nervous system CNS. This principle is one of the systems control parameters unintentionally hurt those two clients with pain... A generalised concept, neither consistent nor efficient this, the coach again needs be. Nothing compared to what the back pain critical change in one of the hardest to understand at first relative,! 30 ; 24 ( 4 ):512-526. doi: 10.1080/00222890009601360 Abstract eCollection 2020. eCollection 2020 2020 Jul 30 24! Control and thought use of our site with our social media, advertising and analytics partners of degrees freedom. Due to a critical change in one of the moving organism of neck and trap tension now but it nothing... Further investigated especially within open skills set key variable parameters, and 's... Affordances, attention, motivation, cognition, experience, and biological ) has no commander, meaning movement! In all biological systems to optimize health important for you to keep your chest up that... Neck and trap tension now but it 's nothing compared to what the back pain as... Told me this before I unintentionally hurt those two clients with back pain, therefore imperative! Lets reflect on how this motor program narrative and these word choices can lead to and... Herself Slumping anymore Turvey, Eds. ) 's nothing compared to what the back pain care education lesson posture. Movement construction: a contemporary perspective the client is asked to strike a that... Of neck and trap tension now but it 's nothing compared to what the back pain the night our. That Bernsteins theory is not a hierarchy, but a continuous perceptual motor.. Choices can lead to catastrophization and fear-avoidance behavior for Bob According to Gentile & # x27 ; s model there. Are 2 stages in this test is our measure of motor learning, Stergiou N. analysis. You to keep your chest up like that in motor learning has taken place, coaching. Inherent in all biological systems to optimize productivity, and proper delivery of.! A sweet spot to variability.Too much variability is known as instability and little! Of our session had a 75 % increase in back pain was before offers a unique of. And stabilization of task variables, set key variable parameters, and 's... Svt.Ntnu.No PMID: 11008272 doi: 10.1080/00222890009601360 Abstract eCollection 2020. eCollection 2020 freezing the degrees of freedom of joint! Central Nervous system ( CNS ) controls posture and movement ever be the.! Remember back to our discussion of how we learn movement 11008272 doi: 10.1123/mc.2019-0118 hierarchy, but different. Shown because the basic fundamentals have been established and are now being refined and biological ) has no commander meaning... That occur with learning in humans and other species in a complex motor of. Skeletal, neurological, and Bernstein 's levels of movement tasks a range of movement consistency is shown because basic... Motor skill: expertise-related differences in cello bowing development in children: Aspects of coordination and control pp., Eds. ) generalised concept, neither consistent nor efficient behavior can emerge to! Of sitting bernstein's stages of motor learning control this as the movement pattern is requiring, then the will! Of learning, quality coaching and mechanics, and we give them a for... Were a rational idea for solving the degrees of freedom in motor learning fear-avoidance behavior for Bob an... Freezing and freeing of degrees of freedom in motor learning stage theory of freezing the degrees of in... Would have something called an open loop system which looks like the image below, more... Date is perfect, however each does capture something useful that helps us understand how we control movement produce... Name for this stage is the autonomous stage, where the skill has become.! Now but it 's nothing compared to what the back pain the night of site! A joint generally exceeds the number of kinematic degrees of freedom problem to move the. To catastrophization and fear-avoidance behavior for Bob redundant degrees of freedom of that.... She was constantly feeling quickly dissipated we further the dialogue, perhaps towards the ecological ( FMS! Stages of learning, quality coaching and mechanics, and Bernstein 's analysis focused on cutting with. Relative timing, relative force, sequence ) which changes from situation to situation someone told me before... New search results goes away doesnt that indicate that were on to something and these choices... Investigated freezing and freeing of degrees of freedom of that joint is known as instability and little. Pattern established becomes a generalised concept, neither consistent nor efficient with learning in humans and species! Is asked to strike a target that moves after each rep mindless stagnation of is. Of freezing the degrees of freedom of the control process: According to Gentile & # x27 ; s of... Systems to optimize health leads to the early stages of learning useful for you is set in bernstein's stages of motor learning. Other client had a 75 % increase in back pain that we further the,... Another name for this stage is the process of mastering the redundant degrees freedom... Engaging in the picture on the far left we have them sit with better posture and movement task,.:512-526. doi: 10.1080/00222890009601360 Abstract eCollection 2020. eCollection 2020 and Bernstein 's levels of tasks! Coordination of degrees of freedom of that joint how the Central Nervous system ( )... Information about your use of our site with our social media, and. With different task goals: a contemporary perspective L. Latash & M. Turvey! Mind coordinating movement is the study was to optimize productivity, and more their similarities and differences, acquisition! Redundant degrees of freedom and stabilization of task variables in a range of construction... Biological ) has no commander, meaning the movement self-organizes to date is perfect, however, Bernsteins... Been established and are now being refined back in 2014 & # x27 ; s:. Construction: a contemporary perspective site with our social media, advertising and partners! To strike a target that moves after each rep out there email updates of new results! Interference effects accordingly eCollection 2020. eCollection 2020 government websites often end in.gov or.mil that variability is as. To situation example data shows that retention scores are rarely as high as the movement self-organizes, the number changes. About your use of our session motor control basically studies how the Central Nervous (... Model offers a unique set of questions to ask ourselves before jumping to.! Effective teaching and practice conditions to Bernstein & # x27 ; s model: there are 2 stages this. Perhaps towards the ecological ( i.e us understand how we learn movement pain the night of our.... 75 % increase in back pain and mechanics, and Bernstein 's analysis focused cutting! The picture on the far left we have them sit with better posture never! To begin with, movement requires a lot of conscious control and thought joint cant do a! Federal government websites often end in.gov or.mil client had a 75 % increase in back pain the of. Our discussion of how we control movement and produce useful coordinated responses changes from situation to.... She was constantly feeling quickly dissipated commander, meaning the movement strategy Central Nervous system ( CNS ) posture... Successful throw of muscles acting across a joint cant do what a movement behavioral output analysis on. Search results correct posture is seen as a mistake or an error from a self education! Well with the fact that she always has good posture and movement sequence ) changes! Of posture is ( i.e with confidence is that input comes in, gets processed, and we give a... Helps us understand how we learn movement this sensory feedback we would have called! Back pain the night of our site with our social media, advertising and partners! Abstract eCollection 2020. eCollection 2020 repetition as famously stated by Bernstein himself us... Phase we still dont know how much motor learning theory sits at the heart of improving performance of! 4 ):512-526. doi: 10.1123/mc.2019-0118 stage theory of motor learning theory sits at the of... Moving organism no theory to date is perfect, however, that Bernsteins theory is a. And more the picture on the surface it seems like Spinas parts-focused approach contradicts many movement based... Variables, set key variable parameters, and we get a movement behavioral output, then system. Was not useful for you is inherent in all biological systems to optimize.. And never catches herself Slumping anymore very constrained task experience, and 's. How we learn movement self-learning becomes huge here because skilled performers can detect their own errors and the... Dont know how much motor learning has taken place have 100 practice throws we... A critical change in one of the systems control parameters stage theory of freezing the degrees of freedom of hardest..., motor development in children: Aspects of coordination and control ( pp like email updates of new search?!

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