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Physical literacy has become an increasingly influential concept in the past few decades, and is being woven into education, sport, and recreation policy and practice, particularly in Canada. The term is based on a metaphor that likens movement fluency to language literacy. Use of a metaphoric rather than a theoretical foundation has enabled various interpretations and re-definitions of the term. This article aims at an understanding of physical literacy that encompasses and reunifies the interpretations, helping physical literacy to be theoretically understood, practically researched, and instrumentally employed. The division of the holistic physical literacy concept into various interpretations is traced and the metaphoric basis of physical literacy is discussed. Through this analysis the unifying theme of communication is identified, and based on this a new definition of physical literacy is advanced and a model of physical literacy development is proposed. A series of questions that invite a multi-disciplinary approach to physical literacy research is presented. [ABSTRACT FROM AUTHOR]

We tested a prediction that equifinality at the task level may be accompanied by violations of equifinality within the redundant set of elemental variables. Seated subjects grasped a handle, and occupied an initial arm configuration against a bias force produced by a robot. The robot applied a smooth, transient change in the force (perturbation). The subjects were instructed "not to intervene voluntarily" with hand deviations. After the robot force returned to the bias value, the hand returned close to the original position and orientation. Analysis of across-trials variance in the joint configuration space confirmed that most variance of the difference between the initial and final states was compatible with unchanged values of both hand position and orientation. These results provide direct support for the theoretical scheme that combines the ideas of synergies and control with referent configurations. [ABSTRACT FROM AUTHOR]

This study examined how pleasant and unpleasant emotional states influence the biomechanical organization of both forward and backward step initiation (SI). Participants (N = 31) purposely took a single step toward or away from a screen following the presentation of a pleasant (erotic), unpleasant (mutilation) or neutral (objects and landscapes) image. The main results showed that the reaction time for forward SI was shortened when individuals were exposed to pleasant pictures as compared with unpleasant pictures. The anticipatory whole-body center-of-mass velocity associated with backward SI, as well as the peak of center-of-mass velocity associated with forward SI both reached lower values when individuals were exposed to pleasant pictures as compared with neutral pictures. In contrast, unpleasant pictures did not significantly induce any change in the forward or backward SI parameters. Overall, these results obtained for whole-body approach/ avoidance-like behaviors provided mitigated support for the so-called "motivational direction hypothesis." [ABSTRACT FROM AUTHOR]

We investigated the effects of contralateral movement on the soleus H-reflex during bilateral movement of the ankles. The soleus H-reflex was evoked during unilateral or in-phase or antiphase bilateral ankle movement in healthy humans. The soleus H-reflex amplitude during antiphase movement was not significantly different from that during in-phase movement. The H-reflex amplitude during in-phase movement was not significantly different from that during unilateral movement of the tested ankle. The H-reflex amplitude in the maximal plantar flexion phase of the tested ankle during antiphase movement was significantly smaller than that in the corresponding phase during unilateral movement. The amount of the decrease was 21%. The effect of contralateral movement is prominent during antiphase movement of the ankles. [ABSTRACT FROM AUTHOR]

To investigate how sensory symptoms impact the motor control of hands, in this study we examined the differences in conventional sensibility assessments and pinch force control in the pinch-holding-up activity (PHUA) test between carpal tunnel syndrome (CTS) patients and healthy controls. CTS patients (n = 82) with 122 affected hands and an equal number of control subjects were recruited to participate in the threshold, discrimination, and PHUA tests. The patients showed significantly poorer hand sensibility and lower efficiency of force adjustment in the PHUA test as compared with the control subjects. Baseline pinch strength and the percentage of maximal pinch strength for the PHUA were significantly higher for the subgroup of sensory nerve action potential (SNAP) of <16 μV than for the subgroup of SNAP of ³16 μV. Using a PHUA perspective to analyze the efficiency of force-adjustment could assist the clinical detection of sensory nerve dysfunction. [ABSTRACT FROM AUTHOR]

Our study aimed to determine whether electrical and mechanical factors contributing to acute or long-term maximal torque reduction and muscle soreness due to submaximal eccentric exercise (ECC) are elbow-joint-angle specific and to what extent the joint angle affects the contribution of antagonist coactivation to this torque reduction. Maximal isometric torque (MIT), muscle soreness assessment, agonist electromechanical activities, and antagonist coactivation during the maximal voluntary contraction (MVC) were measured at elbow joint angles of 60°, 90°, and 150° before ECC, immediately after exercise, and 24, 48, 72, and 120 hr after exercise. ECC causes an immediate decrease in MIT as well as increased antagonist coactivation at three angles. Antagonist coactivation returned to its baseline level at 24 hr regardless of joint angle. The most rapid torque recovery and the highest force level at which pain occurred were found after ECC at a joint angle of 60°. During the recovery period, no mechanomyographical changes were observed when measuring surface mechanomyography changes at three angles, while the electrical activity differed between angles. [ABSTRACT FROM AUTHOR]

This study set out to determine whether the fastest online hand movement corrections are only responses to changing judgments of the targets' position or whether they are also influenced by the apparent target motion. Introducing a gap between when a target disappears and when it reappears at a new position in a double-step paradigm disrupts the apparent motion, so we examined the influence of such a gap on the intensity of the response. We found that responses to target perturbations with disrupted apparent motion were less vigorous. The response latency was 10 ms shorter when there was a gap, which might be related to the gap effect that has previously been described for initiating eye and hand movements. [ABSTRACT FROM AUTHOR]

This longitudinal study examined the movement efficiency of typically developing children between 7 and 9 years of age by scrutinizing their movement amplitudes and frequencies as they settled into a loop-writing task in which both parameters were prescribed. It was hypothesized that during the first three grades at primary school children would show increasing efficiency in exploiting the inverse relationship between movement amplitude and frequency when adjusting their movement errors. Whereas a clear developmental trend showed increasing efficiency with respect to the way in which the primary school children met the amplitude constraints, a more variable pattern was found for the age-dependent adjustments to the frequency requirements. At the level of parameter-error corrections from one cycle to the next, a marginal developmental trend was observed. Results are discussed in terms of contrasting effects between educational targets and movement-efficiency principles. [ABSTRACT FROM AUTHOR]

We compared two standard methods routinely used to assess the grip force (GF; perpendicular force that hand exerts upon the hand-held object) in the studies of coordination of GF and load force (LF; tangential force) in manipulation tasks. A variety of static tasks were tested, and GF-LF coupling (i.e., the maximum cross-correlation between the forces) was assessed. GF was calculated either as the minimum value of the two opposing GF components acting upon the hand-held object (GFmin) or as their average value (GFavg). Although both methods revealed high GF-LF correlation coefficients, most of the data revealed the higher values for GFavg than for GFmin. Therefore, we conclude that the CNS is more likely to take into account GFavg than GFmin when controlling static manipulative actions as well as that GFavg should be the variable of choice in kinetic analyses of static manipulation tasks. [ABSTRACT FROM AUTHOR]

Empirical evidence suggests that the ability to stabilize important task variables of everyday movements by synergistically coordinating redundant degrees of freedom decreases with aging. The aim of the current study was to investigate whether this decrease may be regarded as a characteristic that also applies for the control of multiple task variables. We asked younger and older subjects to repeatedly reach towards and grasp a handle, while joint angle movement of the arm was recorded. The handle constrained final hand position and final hand orientation. Movement variability was analyzed during movement execution by using the uncontrolled manifold method. Results showed that hand orientation was less stabilized in younger than in older subjects. We conclude that aging changes the stability of important task variables. These changes may lead to decreased stability in some task variables, as reported in the literature, but also to increased stability in other task variables. [ABSTRACT FROM AUTHOR]

Few examined the contribution of neural and muscular deficits to weakness in the same stroke subject. We determined maximal voluntary contraction (MVC) and 50 Hz torques, activation (twitch interpolation), electromyographic (EMG) amplitude and antagonist coactivation, and muscle volume using magnetic resonance imaging (MRI) of the dorsiflexors bilaterally in 7 chronic stroke subjects (40-67 y). Recordings of MVC and 50 Hz torque were also done in 7 control subjects (24-69 y) without stroke. The MVC torque was smaller in the contralesional than ipsilesilesional limb (29.8 ± 21.3 Nm vs. 42.5 ± 12.0 Nm, p = .04), and was associated with deficits in activation (r2 = .77) and EMG amplitude (r2 = .71). Antagonist coactivation percentage was not significantly different between limbs. Muscle volume, 50 Hz torque, and specific torque (50Hz torque/muscle volume) were also not different between sides. The concept that atrophy is commonplace after stroke is not supported by the results. Our findings indicate that dorsiflexor weakness in mobile stroke survivors is not explained by atrophy or reduced torque generating capacity suggesting an important role for central factors. [ABSTRACT FROM AUTHOR]

This study examined the effect of visual feedback and force level on the neural mechanisms responsible for the performance of a motor task. We used a voxel-wise fMRI approach to determine the effect of visual feedback (with and without) during a grip force task at 35% and 70% of maximum voluntary contraction. Two areas (contralateral rostral premotor cortex and putamen) displayed an interaction between force and feedback conditions. When the main effect of feedback condition was analyzed, higher activation when visual feedback was available was found in 22 of the 24 active brain areas, while the two other regions (contralateral lingual gyrus and ipsilateral precuneus) showed greater levels of activity when no visual feedback was available. The results suggest that there is a potentially confounding influence of visual feedback on brain activation during a motor task, and for some regions, this is dependent on the level of force applied. [ABSTRACT FROM AUTHOR]

This study investigated activity of the embouchure-related orofacial muscles during pre- and postattack phases of sound production by I 0 trained French-horn players. Surface electromyogram (EMG) from five selected facial muscles, and related facial skin kinematics were examined in relation to pitch and intensity of a tone produced. No difference in EMGs and facial kinematics between the two phases was found, indicating importance of appropriate tbrmation of preattack embouchure. EMGs in all muscles during the postattack phase increased linearly with an increase in pitch, and they also increased with tone intensity without interacting with the pitch effect. Orofacial skin movement remained constant across all pitches and intensities except for lateral retraction of the lips during high-pitch tone production. Contraction of the orofacial muscles is fundamentally isometric by which tension on the lips and the cheeks is regulated for flexible sound parameter control. [ABSTRACT FROM AUTHOR]

Previous studies indicate that rifle shooting performance while standing is compromised when fatigued. Apprehension of suspects by police officers may involve foot pursuit and firing a weapon from a standing position. The purpose of the current study was to investigate pistol shooting performance in police officers under similar conditions of physical fatigue. Participants (mean age: 30.1 years; 4.4 years of experience as police officer) completed two shooting trials separated by an acute bout of exercise on a cycle ergometer to voluntary exhaustion. Each trial consisted of three rounds of five rapid-fire shots at a target, each round separated by a 15-s rest. Participants' backs were turned to the target between rounds. Despite physical exertion, with an average heart rate of 164 bpm, shooting accuracy (mean distance of the closest 4 shots from the center of the target) and precision (diameter of the tightest 4-shot grouping) remained unchanged on postexercise trials relative to preexercise trials. This suggests that automatic shooting reactions override the adverse consequences of fatiguing exercise on shooting performance. [ABSTRACT FROM AUTHOR]

The capacity for random movement production is known to be limited in humans (e.g., Newell, Deutsch, & Morrison, 2000). We examined the effects of a brief mindfulness induction on random movement production because there are useful implications for variability in solving movement-related problems. The main task involved randomly clicking the 9 boxes in a 3 x 3 grid presented on a computer screen for five minutes. We characterized the sequence of clicking in terms of degrees of randomness, or periodicity, based on the fit, or probability, of the experimental data with its best fitting Bayesian network (4-click memory nodes) using the Markov chain Monte Carlo (MCMC) approach. Sixty-three participants were randomly assigned to either the experimental or the control condition. Mixed design repeated-measures ANOVA results show that the short mindfulness induction had a positive effect on the randomness of the sequence subsequently produced. This finding suggests that mindfulness may be a suitable strategy for increasing random movement behavior. [ABSTRACT FROM AUTHOR]

This study investigated the possible role of the corticospinal system during force generation and force relaxation. Nine young and healthy subjects were instructed to produce a total lbrce with four fingers within a hand following a preset force generation and relaxation ramp template closely. Excitability of corticospinal (CS) projections was assessed by single- and paired-pulse TMS. Errors introduced by a finger force were partially compensated by other finger forces during force generation, but were amplified during force relaxation. The CS excitability was greater during force generation than maintenance or relaxation. No difference in intracortical inhibition or facilitation was found. Nonnormalized finger extensor EMG responses remained unchanged. The findings suggest that force relaxation is not just a withdrawal from activation, and multifinger interactions are likely controlled beyond the primary motor cortex. [ABSTRACT FROM AUTHOR]

The present investigation examined whether perfectionism might predict whether an athlete would suffer from the 'yips' (a long term movement disorder consisting of involuntary movements that affects the execution of motor skills). A sample of 'yips'-affected individuals from golf, cricket, and darts as well as a sport-matched sample of non 'yips'-affected athletes completed the shortened version of Frost, Marten, Lahart, and Rosenblate's (1990) multidimensional perfectionism scale (FMPS). Results revealed that three aspects of perfectionism (personal standards, organization, and concern over mistakes) were associated with a greater likelihood of suffering from the 'yips', indicating that 'yips' sufferers had an unhealthy perfectionism profile. The results highlight perfectionism as a possible antecedent of the 'yips' experience within sport. [ABSTRACT FROM AUTHOR]

In this study, two force platforms were synchronized to investigate the coordination of the right and left foot center of pressure (COPR and COPL) and its relation to the COPNET in the control of 5 upright postures with and without visual information. The results revealed that the standard deviation (SD) of COPL, COPR, and COPNET progressively increased in the more challenging staggered and tandem stances, respectively, and to a lesser degree with the absence of visual information. Circular analysis of the relative phase of COPL and COPR revealed that the coupling pattern and variability were dependent on postural stances and the availability of vision. A negative correlation between the variability of the relative phase of the two feet COPs and the SD of the COPNET in the anterior-posterior (AP) direction was evident most strongly in the no vision conditions. Thus, the asymmetry of the mechanical constraints on the feet as a function of stance organize the coordination patterns of the feet COPs while the degree of adaptive variation between the feet COPs is dependent on both the mechanical constraints and the availability of vision. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate central nervous system (CNS) strategies for controlling multifinger forces during a circle-drawing task. Subjects drew 30 concentric, discontinuous clockwise and counter clockwise circles, at self and experimenter-set paces. The three-dimensional trajectory of the pen's center of mass and the three-dimensional forces and moments of force at each contact between the hand and the pen were recorded. Uncontrolled Manifold Analysis was used to quantify the synergies between pen-hand contact forces in radial, tangential and vertical directions. Results showed that synergies in the radial and tangential components were significantly stronger than in the vertical component. Synergies in the clockwise direction were significantly stronger than the counterclockwise direction in the radial and vertical components. Pace was found to be insignificant under any condition. [ABSTRACT FROM AUTHOR]

Low-skill golfers coordinate the movements of their head and putter with an allocentric, isodirectional coupling, which is opposite to the allocentric, antidirectional coordination pattern used by experts (Lee, Ishikura, Kegel, Gonzalez, & Passmore, 2008). The present study investigated the effects of four vision conditions (full vision, no vision, target focus, and ball focus) on head-putter coupling in low-skill golfers. Performance in the absence of vision resulted in a level of high isodirectional coupling that was similar to the full vision condition. However, when instructed to focus on the target during the putt, or focus on the ball through a restricted viewing angle, low-skill golfers significantly decoupled the head--putter coordination pattern.. However, outcome measures demonstrated that target focus resulted in poorer performance compared with the other visual conditions, thereby providing overall support for use of a ball focus strategy to enhance coordination and outcome performance. Focus of attention and reduced visual tracking were hypothesized as potential reasons for the decoupling. [ABSTRACT FROM AUTHOR]

We used the event-related potential (ERP) methodology to examine differences in neural processing between visually and memory-guided reaches. Consistent with previous findings (e.g., Westwood, Heath, & Roy, 2003), memory-guided reaches undershot veridical target location to a greater extent than their visually guided counterparts. Analysis of the ERP data revealed that memory-guided reaches were associated with reduced potentials over medial-frontal cortex at target presentation and following movement onset. Further, we found that the amplitudes of the potentials over medial-frontal cortex for visually and memory-guided reaches were significantly correlated with the peak accelerations and decelerations of the reaching movements. Our results suggest that memory-guided reaches are mediated by a motor plan that is generated while a target is visible, and then stored in memory until needed--a result counter to recent behavioral theories asserting that memory-guided reaches are planned just before movement onset via a stored, sensory-based target representation. [ABSTRACT FROM AUTHOR]

This study investigated the asymmetry of bilateral interference in relation to the relative difference of force amplitude between hands and the hand dominance. In Experiment 1, one hand produced a fixed constant force of 5% maximum voluntary contraction (MVC) while the other hand produced different constant forces of 5%, 20%, and 50% MVC in blocked conditions. Asymmetric interference in force amplitude alone was evident in that the hand producing the fixed low force showed a stronger interference than the hand performing the higher force. Asymmetric interference in hand dominance was also found in that more interference was observed when the nondominant left hand produced the higher force, a finding that does not support the hemisphere specialization hypothesis. Experiment 2 was performed to rule out the fixed force level interpretation compared with the low force level account and the fixed force was set at 50% MVC. The results were consistent with the findings in Experiment 1 showing asymmetric interference with force amplitude rather than with fixed force level. The findings revealed that without a timing constraint the task demand associated with force amplitude alone can induce the asymmetric bilateral interference. The external task asymmetry and intrinsic asymmetry of the organism interact and influence the bimanual force coordination and control patterns. [ABSTRACT FROM AUTHOR]

One question facing kinesiologists today is how to implement findings from research into society, in this case, physical education. In this paper I examine the role of a balanced approach to educational physical education in promoting physical activity. I argue that limiting physical education to simple tasks that encourage students to workout at target heart rate to expend calories is not an effective solution to the long-term challenge of promoting physically active lifestyles. As an alternative, I discuss research findings associated with motor skill competence, perceived competence, and knowledge growth that can increase individuals' options to participate in many different types of physical activity at greater intensities and for longer durations. I conclude by considering the role of educational physical education in public health initiatives with the goal of influencing students' decisions to embrace physical activity for a lifetime. [ABSTRACT FROM AUTHOR]

On the basis of simulations carried out with a finite element biomechanical model of the face, the influence of the muscle stress stiffening effect was studied for the protrusion/rounding of the lips produced with the Orbicularis Oris (OO). It is shown that the stress stiffening effect influences lip shape. When stress stiffening is modeled, the variation in the crucial geometrical characteristics of the lips shows a clear saturation effect as the OO activation level increases. Similarly, for a sufficient amount of OO activation, a saturation effect is observed when stiffening increases. In both cases, differences in lip shaping associated with the absence or presence of stiffening have consequences for the spectral characteristics of the speech signal obtained for the French vowel /u/. These results are interpreted in terms of their consequences for the motor control strategies underlying the protrusion/ rounding gesture in speech production. [ABSTRACT FROM AUTHOR]

The article introduces research reported in this issue on speech motor control, noting topics that include general aspects of motor control, comparisons of motor control in speech production with that of limb movements, and elucidation of how syllable frequency and complexity influence processes of speech motor control.

There are still crucial gaps in our knowledge about developmental paths taken by children to adult-like speech motor control. Mature control of articulators during speaking is manifested in the appropriate extent of coarticulation (the articulatory overlap of speech sounds). This study compared lingual coarticulatory properties of child and adult speech, using ultrasound tongue imaging. The participants were speakers of Standard Scottish English, ten adults and ten children aged 6-9 years. Consonant-vowel syllables were presented in a carrier phrase. Distances between tongue curves were used to quantify coarticulation. In both adults and children, vowel pairs /a/-/i/ and /a/-/u/ significantly affected the consonant, and the vowel pair /i/-/u/ did not. Extent of coarticulation was significantly greater in the children than in the adults, providing support for the notion that children's speech production operates with larger units than adults'. More within-speaker variability was found in the children than in the adults. [ABSTRACT FROM AUTHOR]

Adult speakers have developed precise forward models of articulation for their native language and seem to rely less on auditory sensory feedback. However, for learning of the production of new speech sounds, auditory perception provides a corrective signal for motor control. We assessed adult German speakers' speech motor learning capacity in the absence of auditory feedback but with clear somatosensory information. Learners were presented with a nonnative singleton-geminate duration contrast of voiceless, unaspirated bilabial plosives /p/ vs. /pp/ which is present in Italian. We found that the lack of auditory feedback had no immediate effect but that deviating productions emerged during the course of learning. By the end of training, speakers with masked feedback produced strong lengthening of segments and showed more variation on their production than speakers with normal auditory feedback. Our findings indicate that auditory feedback is necessary for the learning of precise coordination of articulation even if somatosensory feedback is salient. [ABSTRACT FROM AUTHOR]

This paper presents a comparative conceptual review of speech and limb motor control. Speech is essentially cognitive in nature and constrained by the rules of language, while limb movement is often oriented to physical objects. We discuss the issue of intrinsic vs. extrinsic variables underlying the representations of motor goals as well as whether motor goals specify terminal postures or entire trajectories. Timing and coordination is recognized as an area of strong interchange between the two domains. Although coordination among different motor acts within a sequence and coarticulation are central to speech motor control, they have received only limited attention in manipulatory movements. The biomechanics of speech production is characterized by the presence of soft tissue, a variable number of degrees of freedom, and the challenges of high rates of production, while limb movements deal more typically with inertial constraints from manipulated objects. This comparative review thus leads us to identify many strands of thinking that are shared across the two domains, but also points us to issues on which approaches in the two domains differ. We conclude that conceptual interchange between the fields of limb and speech motor control has been useful in the past and promises continued benefit. [ABSTRACT FROM AUTHOR]

This reply to the Commentaries is focused on two archetypes of motor control research, one based on physics and physiology and the other based on control theory and ideas of neural computations. The former approach, represented by the equilibrium-point hypothesis, strives to discover the physical laws and salient physiological variables that make purposeful coordinated movements possible. The latter approach, represented by the ideas of internal models and optimal control, tries to apply methods of control developed for man-made inanimate systems to the human body. Specific issues related to control with subthreshold membrane depolarization, motor redundancy, and the idea of synergies are briefly discussed. The nine commentaries represent a broad spectrum of attitudes towards the central ideas of the target article, from highly positive and encouraging to strongly critical. I would like to start on a positive note and emphasize the clear shift in the general attitude towards the equilibrium-point (EP) hypothesis. It was not surprising to read the overall positive commentaries by Feldman, Levin, and Scholz. However, even the commentators who are known for their critical attitude to the EP-hypothesis (Shadmehr and Loeb) do not claim that the EP-hypothesis is meaningless and has been proven to be false. This is definitely a welcome trend, particularly when compared to the relatively recent fashion of "disproving" the EP-hypothesis and claiming that it is hopelessly wrong (Gomi & Kawato 1996; Gottlieb 1998; Hinder & Milner 2003; Popescu et al. 2003). Only five years ago, one of the commentators wrote: "…convincing evidence shows that the CNS does not use the equilibrium-point control method…" (Shadmehr & Wise, 2005; p. 143). The current commentary by Shadmehr avoids such strong statements. The commentators raise many important issues, and, given the format of this paper, I will be unable to address them all in sufficient detail. So, I will focus on a few issues that seem to me central for the current state and the vector of development of the field of motor control. [ABSTRACT FROM AUTHOR]

The article presents commentary on research reported in an accompanying article in the issue by researcher Mark L. Latash and colleagues on motor control and an Hierarchical Equilibrium Point Hypothesis (HEPH). The authors summarize the hypothesis in regard to central and lower-level controllers involved in muscle control, which they say is consistent with a so-called lambda model. The authors discuss other approaches and models of motor control including Internal models (IM), Optimal control (OC), neural IM, and neural Control, nC. The HEPH is said to be a version of nC.

This study systematically investigates the temporal organization of American English onset and coda consonant clusters on the basis of kinematic data. Results from seven speakers suggest that consonants in complex onsets are organized globally with respect to the following vowel, while consonants in complex codas are organized locally relative to the preceding vowel. These results support the competitive coupling model hypothesized for complex onsets, a model according to which consonant gestures in onsets are each coupled in-phase to the vowel, and antiphase with each other. The results are overall also consistent with the noncompetitive coupling relations assumed for codas, by which only the first consonant in a cluster is coupled antiphase with the vowel, and any subsequent consonants are coupled antiphase to each other. However, our data also show that the segmental composition of the cluster affects the timing relationship in codas, particularly /lC/ coda clusters pattern differently from other clusters and do not adhere to the predicted timing relations. The data contribute to our understanding of the interaction of linguistic structure and motor control of the articulators in speech production. [ABSTRACT FROM AUTHOR]

Exercise seems to attenuate the postural control system and anticipatory postural adjustments (APAs) decline, but no conclusive findings are available. This study analyses, in elderly people, the exercise effect in APAs during the raising of a load with both arms in the sagittal plane. Twenty eight males over the age of 60 (65,8 ± 4,07 yr old)—9 veterans in exercising, 9 who exercise recently, and 10 sedentary—were asked to raise a load with both arms simultaneously to shoulder level, in standing position, as fast as possible. It was studied the electromyography (EMG) pattern of the main muscles. The APAs were quantified through the time integral of EMG records (iEMG). Anticipatory changes in the postural muscles were seen in all groups. We observed, in the tibialis anterior activity, a higher significant activation in the sedentary compared with the other groups, suggesting that exercise can modulate the postural control system. [ABSTRACT FROM AUTHOR]

The author comments on an accompanying article in the issue by researcher Mark L. Latash on synergies in human motor control associated with the central nervous system. The author comments on Latash's explanation of movement and the advantages afforded by system redundancies that allow different people to move in different ways. The author comments that Latash's discussion of flexible synergies differs from more rigid models of the neuromusculoskeletal system. The author comments on the application of the concept of synergies and the uncontrolled manifold (UCM) approach in assessing the effectiveness of neurological rehabilitation.

Experimental studies show intact implicit motor learning in patients with Alzheimer's disease (AD) but the results for patients with Parkinson's disease (PD) are inconclusive. This study tests implicit sequence learning in AD and PD patients, and healthy controls, using the classical Serial Reaction Time Task (SRTT), and a somewhat similar Pattern Learning Task (PLT), which involves stylus movements in different directions, and which allows detailed movement analysis. As expected, the time measures showed less implicit motor learning in the PD patients relative to the other groups in both tasks, but their error percentages increased when the sequence changed from a fixed to a random order, which is indicative of implicit learning. The AD patients showed a reversed pattern of results. Arguably, errors and time measures may reflect the involvement of separate processes, e.g., spatial and motor components, which could be differently affected in AD and PD. [ABSTRACT FROM AUTHOR]

The author discusses an accompanying article in the issue by Mark L. Latash and colleagues on the human motor control system. The author cites other researchers whose perspectives on neural motor controllers differ from that of Latash and his team. The author refers to researcher A.G. Feldman and his school of thought on motor control that he says Latash adheres to. The author also comments on Latash's scheme of control hierarchy, calling it logical, but paradoxical. The author says that the paradox relates to the central nervous system and the variance of output signal availability with the level of hierarchy.

The article offers a way to unite three recent developments in the field of motor control and coordination: (1) The notion of synergies is introduced based on the principle of motor abundance; (2) The uncontrolled manifold hypothesis is described as offering a computational framework to identify and quantify synergies; and (3) The equilibrium-point hypothesis is described for a single muscle, single joint, and multijoint systems. Merging these concepts into a single coherent scheme requires focusing on control variables rather than performance variables. The principle of minimal final action is formulated as the guiding principle within the referent configuration hypothesis. Motor actions are associated with setting two types of variables by a controller, those that ultimately define average performance patterns and those that define associated synergies. Predictions of the suggested scheme are reviewed, such as the phenomenon of anticipatory synergy adjustments, quick actions without changes in synergies, atypical synergies, and changes in synergies with practice. A few models are briefly reviewed. [ABSTRACT FROM AUTHOR]

The author comments on the uncontrolled manifold (UCM) hypothesis and synergy concept of motor control. The author discusses the function of the brain in solving redundancy problems in motor control. The author defines redundancy in motor control and notes that the flexibility it affords likely played a key role in human evolution and survival. The author refers to an accompanying article by investigator Mark L. Latash and his group that he says supports the synergy concept. The UCM-synergy approach is said to disregard the actual means of execution and control of motor actions.

This study investigated the effectiveness of a 20-week Simulated Developmental Horse-Riding Program (SDHRP) by using an innovative exercise equipment (Joba®) on the motor proficiency and sensory integrative functions in 60 children with autism (age: 6 years, 5 months to 8 years, 9 months). In the first phase of 20 weeks, 30 children received the SDHRP in addition to their regular occupational therapy while another 30 children received regular occupational therapy only. The arrangement was reversed in the second phase of another 20 weeks. Children with autism in this study showed improved motor proficiency and sensory integrative functions after 20-week SDHRP (p < .01). In addition, the therapeutic effect appeared to be sustained for at least 24 weeks (6 months). [ABSTRACT FROM AUTHOR]

Although using a treadmill workstation may change the sedentary nature of desk jobs, it is unknown if walking while working affects performance on office-work related tasks. Purpose: To assess differences between seated and walking conditions on motor skills and cognitive function tests. Methods: Eleven males (24.6 ± 3.5 y) and 9 females (27.0 ± 3.9 y) completed a test battery to assess selective attention and processing speed, typing speed, mouse clicking/drag-and-drop speed, and GRE math and reading comprehension. Testing was performed under seated and walking conditions on 2 separate days using a counterbalanced, within subjects design. Participants did not have an acclimation period before the walking condition. Results: Paired t tests (P < .05) revealed that in the seated condition, completion times were shorter for mouse clicking (26.6 ± 3.0 vs. 28.2 ± 2.5s) and drag-and-drop (40.3 ± 4.2 vs. 43.9 ± 2.5s) tests, typing speed was greater (40.2 ± 9.1 vs. 36.9 ± 10.2 adjusted words · min-1), and math scores were better (71.4 ± 15.2 vs. 64.3 ± 13.4%). There were no significant differences between conditions in selective attention and processing speed or in reading comprehension. Conclusion: Compared with the seated condition, treadmill walking caused a 6% to 11% decrease in measures of fine motor skills and math problem solving, but did not affect selective attention and processing speed or reading comprehension. [ABSTRACT FROM AUTHOR]

In the presence of motor redundancy, recent studies have shown that goal equivalent configurations of the body segments might be used by the central nervous system (CNS) instead of stereotypical movement patterns. In particular, some authors have shown that the CNS might choose a subset of joint configurations (termed the uncontrolled manifold or UCM) such that variability (goal equivalent variance or GEV) in this subset does not affect the value of a particular performance variable while variability in the orthogonal subset ORT (non-goal equivalent variance or NGEV) does. This hypothesis has been used successfully to test whether specific performance variables such as endpoint trajectory or segment global orientation are stabilized by the CNS or to study the influence of constraints on the organization of the movement. Few studies have examined the redundancy problem when considering obstacle avoidance during a grasping task. Indeed, the majority of the works on this topic considers non redundant arm models or do not take into account the movement variability. In the present work, we sought to study the coordination of the trunk and the arm during a reaching task involving an obstacle and to test whether such a spatial constraint in extrinsic space may induce particular adaptations in term of joint flexibility when considering the shoulder, elbow, and wrist joint center positions. In this framework, the upper limb three-dimensional kinematics was recorded. From the calculated joint angles, the variability in joint space related to the three joint center positions was computed and decomposed into GEV and NGEV. In agreement with the UCM hypothesis, results showed higher values of GEV than NGEV for all the experimental conditions. The main finding of the study is that joints' synergy is strengthened for the stabilization of the elbow joint center position during the late phases of the movement. This strengthening seems to be due mainly to an increase of GEV. Therefore, our results suggest that an increase of joint flexibility may be a mechanism by which the CNS takes into account a spatial constraint in extrinsic space represented by an obstacle. [ABSTRACT FROM AUTHOR]

The aim of this study is to establish the effects of stick use on rhythmic bimanual coordination in drummers. Eighteen drummers performed a rapid antiphase coordination task using their fingers and handheld drumsticks. We found no significant differences in the speed of tapping between finger and stick-use tapping, while stick-use tapping had a larger peak force and smaller variability in coordination pattern than finger tapping. As a consequence, the quotient of the number of taps divided by the variability of coordination pattern, named the bimanual performance quotient, was higher for stick-use tapping than for finger tapping. A significant correlation was found between years of drumming experience and the bimanual performance quotient for both finger and stick-use tapping, but not between the years of drumming experience and the degree of improvement in the bimanual performance quotient with stick use relative to finger tapping. These results indicate that stick use enhances drummers' bimanual coordination during rapid alternate tapping, whereas the degree of improvement with stick use does not depend on drumming experience. [ABSTRACT FROM AUTHOR]

This paper presents the stochastic modeling of isometric force variability in the steady-state time series recorded from the index finger of young adults in the act of attempting to hold different levels of constant force. The isometric force time series were examined by assuming that the stochastic (random) models were linear. System identification techniques were employed to estimate the parameters of each linear model. Once the models were parameterized, the values of the estimated parameters were compared to determine if a single linear time-invariant model was applicable across the entire isometric force range. Although the overall random models were found to be nonlinear functions of the target force level, within a fixed target level, linear modeling provided adequate estimates of the underlying processes thus enabling the use of well-known linear system identification algorithms. [ABSTRACT FROM AUTHOR]

We studied the mechanical variables (the grip force and the total moment of force) and multidigit synergies at two levels (the virtual finger-thumb level, VF-TH, and the individual finger level, IMRL) of a hypothetical control hierarchy during accurate rotation of a hand-held instrumented handle. Synergies were defined as covaried changes in elemental variables (forces and moments of force) that stabilize the output at a particular level. Indices of multidigit synergies showed higher values at the hierarchically higher level (VF-TH) for both normal and tangential forces. The moment of force was stabilized at both hierarchical levels during the steady-state phases but not during the movement. The results support the principles of superposition and of mechanical advantage. They also support an earlier hypothesis on an inherent tradeoff between synergies at the two hierarchical levels, although the controller showed more subtle and versatile synergic control than the one hypothesized earlier. [ABSTRACT FROM AUTHOR]

Technology has strongly impacted research in kinesiology. Recent technological advances have greatly enhanced our ability to noninvasively quantify activity-related changes in skeletal muscles and peripheral arteries. In people with spinal cord injuries, we can track changes in muscle size, composition, and the presence of injury. We can also measure changes in artery size, health, and the ability to deliver oxygen. However, large investments in time are needed to both obtain these measurements and to be able to interpret them. The monetary costs of advancing technology are rising as well, serving as a major limitation to the promise of technology in kinesiology. [ABSTRACT FROM AUTHOR]

The university is a social institution and as such has a social responsibility to advance knowledge through research that is ultimately meaningful and beneficial to society. As we seek to advance research and graduate education in kinesiology, we must accept ethical standards and professional expectations not only as an institutional value but as an individual value. It is important that we understand current ethical dilemmas, examine underlying factors that might contribute to scientific misconduct and professional misbehavior, and develop professional preparation programs that promote academic and scholarly integrity. Through graduate education in kinesiology, we can provide training in the responsible conduct of research and ethical pursuits so that our graduates can become ethically responsible leaders and scholars. [ABSTRACT FROM AUTHOR]

Stroke patients are often left with hemiplegia or hemiparesis of the upper extremities, severely limiting the ability to perform bimanual and functional activities. No studies have investigated how stroke patients adapt their movements to changes in object size in functionally asymmetric bimanual tasks. The influence of object size on intralimb and interlimb coordination during an asymmetrical, functional bimanual task was examined in patients with left cerebral vascular accidents (LCVA) and healthy controls. Fourteen LCVA patients and 13 age-matched controls were instructed to reach to grasp a large and a small jar with the right/affected hand and to open the cap with the other hand. Movement kinematics was analyzed for intralimb coordination (spatial and temporal planning of reaching and grasping) and interlimb coordination (bimanual synchronization and temporal association of the hands). The results demonstrate a spatial adaptation of reaching in the affected hand to the object size and deficits in temporal planning of grasping with the affected hand to object size in the stroke patients. Movement adaptations of the unaffected hand in the stroke patients were similar to those in the healthy adults. Bimanual coordination was independent of object size for both groups. [ABSTRACT FROM AUTHOR]

Apraxia is a complex movement disorder that frequently occurs following left hemisphere stroke. Studies on patients with apraxia constitute an especially interesting body of literature for motor control researchers who seek to understand the cognitive mechanisms involved in the voluntary control of movement. Reciprocally, among apraxia researchers, great interest exists concerning the ways in which methods and theory from the field of motor control can be brought to bear in the clinical and empirical evaluation of this disorder. Here we will review representative evidence on the etiology, frequency, and assessment of apraxia, and suggest how research methods and theories from the field of motor control can be applied to, and also benefit from, a deeper understanding of apraxia. Parallels are proposed between the major cognitive models of apraxia and motor control to facilitate translation of terminology and concepts, and to enrich the emerging dialogue between these two complementary research domains. [ABSTRACT FROM AUTHOR]

This study examined attentional processes underlying skilled motor performance in threatening situations. Twenty-four trained participants performed a simulated rally driving task under conditions designed either to direct the focus of attention toward the explicit monitoring of driving or a distracting secondary task. Performance (lap time) was compared with a "driving only" control condition. Each condition was completed under nonevaluative and evaluative instructional sets designed to manipulate anxiety. Mental effort was indexed by self-report and dual-task performance measures. The results showed little change in performance in the high-threat explicit monitoring task condition, compared with either the low-threat or the high-threat distraction conditions. Mental effort increased, however, in all high- as opposed to low-threat conditions. Performance effectiveness was therefore maintained under threat although this was at the expense of reduced processing efficiency. The results provide stronger support for the predictions of processing efficiency theory than self-focus theories of choking. [ABSTRACT FROM AUTHOR]

The present investigation sought to examine the nature of the visual information supporting online movement corrections. Participants were instructed to maintain gaze on the veridical endpoint of a neutral Müller-Lyer (ML) configuration in advance and during reaches performed with and without continuous limb vision. At movement onset, the stimulus array remained either the same (i.e., the neutral ML figure) or was perturbed to a fins-in or fins-out ML configuration. We reasoned that our illusion-based paradigm would provide a novel basis to examine the nature of the visual information supporting online movement corrections without the intrusion of putative biased ocular/manual motor interactions. Early reaching kinematics were refractory to the illusion-based perturbation; however, later kinematics were influenced in a direction consistent with the well-documented perceptual effects of the ML illusion. This illusory bias was present irrespective of the presence or absence of limb vision and the corollary extent reaches were controlled online. These results counter the view that metrical visual information specified in an egocentric frame of reference supports online movement corrections (e.g., Glover, 2004). Instead, the present results suggest online movement control is subserved by visual input specified via interacting egocentric and allocentric reference frames. [ABSTRACT FROM AUTHOR]

In two experiments, participants were asked to shift gaze to follow horizontal target oscillation to allow us to investigate relations between eye movements and postural dynamics. Postural sway variability was reduced during target oscillation when compared to sway while viewing a stationary target. The influence of target oscillation on sway was independent of target oscillation frequency. Similar results were obtained with measurements of the center of pressure (Experiment 1) and the displacement of body segments (Experiment 2). The overall results are not consistent with the view that eye movements and postural control compete for limited central processing resources. The results are consistent with the thesis of a functional integration of postural control with visual performance. [ABSTRACT FROM AUTHOR]