bluuebunny/crossref_metadata_2025 huggingface dataset:
The Relationship of Teacher Fitness to Teacher/Student Interaction
Authors: Bischoff Judith A. , Plowman Sharon Ann , Lindenman Lawrence
Published: August 2016

The purpose of this study was to determine the relationship between teacher fitness and teacher/student interaction in the classroom. Eighteen experienced high school teachers volunteered as subjects. Subjects were divided into high-fit (HF) and low-fit (LF) categories by comparison with norms for their age and sex in sit-ups, sit-and-reach, percent body fat, and maximal aerobic power. Teacher/student classroom interaction was evaluated by coding audiotapes with the verbal portion of Cheffers’ Adaptation of Flanders’ Interaction Analysis System (CAFIAS). It was revealed that HF teachers spent less time asking questions and more time giving directions than LF teachers. Teachers initiated talk more in the morning, especially on Monday, and students talked more in the afternoon, especially on Friday. Students initiated more talk in the afternoon and were more unpredictable and noncontent oriented in both their initiated and responding behavior in the afternoon. There were no significant interactions between fitness level, day, and time. The current evidence does not support the hypothesis that physically fit teachers are clearly distinguishable from unfit teachers in terms of teacher/student interaction.
A Systematic Observation of More and Less Successful High School Tennis Coaches
Authors: Claxton David B.
Published: August 2016

The purpose of this study was to describe and analyze systematically the coaching behaviors of more and less successful high school boys’ tennis coaches during practice sessions. The Arizona State University Observation Instrument, consisting of 14 behavior categories, was used to compile data on nine coaches (five judged as more successful and four judged less successful, based on win records). Time sampled event recording was used to collect the data, with each coach being observed during preseason/early season, midseason, and late season for a total of three observations per coach. Analysis of the data showed that the more successful coaches asked a significantly greater number of questions of their players than did the less successful coaches. The tennis coaches demonstrated more instructional behaviors than any other behavior but spent more intervals in the Other category than in any other behavioral category. Other, Management, and Silence accounted for almost 75% of all intervals.
The Effects of a Physical Educator’s Appearance of Body Fatness on Communicating Exercise Concepts to High School Students
Authors: Melville D. Scott , Maddalozzo John G.F.
Published: August 2016

This study was designed to determine if a male physical educator’s appearance of body fatness affects his ability to teach and instill good exercise intentions in high school students. Subjects, 850 students in six schools, viewed one of two 20-minute videotapes in which exercise concepts were presented. The tapes were identical with one exception: In one of the tapes the instructor’s body dimensions were altered by a “fat suit.” Immediately after seeing their tape, the students completed a content examination and questionnaire. Analysis of variance revealed that the viewers of the overweight instructor’s tape scored lower on all aspects of the examination (p < .01). Also, t tests done on their responses to the questionnaire revealed that the students exhibited a lesser intent to exercise (p < .01) and rated less favorably the teacher’s likability, expertise, and appropriateness as a role model (p < .01). Analysis of 2 × 2 (Instructor Appearance × Students Self-Perceived Fitness Levels) ANOVAs done on the students’ intent to exercise, liking of the instructor, appropriateness of the instructor as a model, and knowledgeability of the instructor revealed no interactions (p > .01). It was concluded that a male physical educator’s appearance may be a very powerful mediator of teaching effectiveness. Further ideas for study in this area were suggested and possible implications for teacher education schools were made.
Knowledge Translation: The Role of the Academy in Reducing the ‘Knowledge-to-Action’ Gap
Authors: Weeks Daniel J.
Published: August 2016

This paper, presented as the C. Lynn Vendien International Lecture given at the National Academy of Kinesiology, September 2011, provides context around the concept of accountability, the roles of the Academy, and knowledge translation as the basis for a framework for continued development of the National Academy of Kinesiology. The intent is to use the concepts presented in this paper as a catalyst for further discussion on opportunities for the Academy to serve the field of kinesiology as a knowledge broker and champion in addressing matters of important societal importance. Disability is used as an example of one such immediate opportunity.
A Systems Perspective on Postural and Gait Stability: Implications for Physical Activity in Aging and Disease
Authors: van Emmerik Richard E.A. , Jones Stephanie L. , Busa Michael A. , Baird Jennifer L.
Published: August 2016

Postural instability, falls, and fear of falling that accompany frailty with aging and disease form major impediments to physical activity. In this article we present a theoretical framework that may help researchers and practitioners in the development and delivery of intervention programs aimed at reducing falls and improving postural stability and locomotion in older individuals and in those with disability due to disease. Based on a review of the dynamical and complex systems perspectives of movement coordination and control, we show that 1) central to developing a movement-based intervention program aimed at fall reduction and prevention is the notion that variability can play a functional role and facilitate movement adaptability, 2) intervention programs aimed at fall reduction should focus more on coordination and stability boundary measures instead of traditional gait and posture outcome variables, and 3) noise-based intervention techniques using stochastic resonance may offer external aids to improve dynamic balance control.
Diversity in Kinesiology: Theoretical and Contemporary Considerations
Authors: Hodge Samuel R. , Corbett Doris R.
Published: August 2016

In this article, the authors engage in discourse centrally located in the organizational socialization of Black and Hispanic kinesiology faculty and students within institutions of higher education. First, our commentary is situated in the theoretical framework of organizational socialization in regards to insight about the plight of Black and Hispanic kinesiology professionals. Next, data are presented that highlight the status of Black and Hispanic faculty in academe. Informed by previous research, the authors also discuss the socialization experiences of such faculty in kinesiology programs and departments, particularly at predominantly White institutions of higher education. Lastly, challenges are identified that are associated with recruiting, hiring, retaining, securing tenured status, and advancing Black and Hispanic faculty at leading doctorate-granting institutions in the United States.
Creating an Inclusive Culture and Climate That Supports Excellence in Kinesiology
Authors: Lowrie Patricia M. , Robinson Leah E.
Published: August 2016

The continuing U.S. demographic shifts provide a substantial rationale for a corresponding transformation in the culture and climate of academic departments in higher education. In part, the response to the change is to increase the representation of people of color and others who have been historically absent from professional areas fed by the Kinesiology pipeline. However, the greater challenge is to understand and therefore, alter the internal culture. An intentional effort toward a culture of inclusion and full participation provides a working platform to transform existing practices and to cultivate policies from which emerging practices will offer opportunities for success. The understanding of the multiple identities of those within Kinesiology and the society served, the portals and gaps within the systemic architecture, and the methods of creating a multicultural organization—all play significant roles in contributing to change and transformation. Enlightened catalytic change agents must adopt new inclusive paradigms to prepare 21st century professionals with adaptive ideologies and behaviors for resolving future issues and challenges.
Summary and Conclusions: How Can We Help Enhance Diversity in Kinesiology?
Authors: Hodge Samuel R. , Brooks Dana D. , Harrison Louis
Published: August 2016

This article is divided into two major sections. First, the authors provided interpretations and conclusions about enhancing diversity in kinesiology based on the collection of articles for this Special Theme of the Kinesiology Review. There are six informative articles for this Special Theme on Diversity in Kinesiology that include Why We Should Care about Diversity in Kinesiology by Brooks, Harrison Jr., Norris, and Norwood; Diversity in Kinesiology: Theoretical and Contemporary Considerations by Hodge and Corbett; Creating an Inclusive Culture and Climate that Supports Excellence in Kinesiology by Lowrie and Robinson; Undergraduate Preparedness and Partnerships to Enhance Diversity in Kinesiology by Gregory-Bass, Williams, Blount, and Peters; Creating a Climate of Organizational Diversity—Models of Best Practice by Keith and Russell; and this final article. Second, we identify strategies and provided recommendations to increase the presence and improve the experiences of Black and Hispanic faculty and students in kinesiology programs.
The Standard Model of Talent Development and Its Discontents
Authors: Bailey Richard , Collins David
Published: August 2016

Despite evident differences between approaches to talent development, many share a set of common characteristics and presumptions. We call this the Standard Model of Talent Development (SMTD). This model is articulated and the relevant literature drawn out to highlight the model's strengths and weaknesses. The SMTD has been enormously influential, in terms of both policy documentation and practice, and it retains an obvious common sense appeal. However, we will argue that not only is its attractiveness illusionary and inconsistent to the emerging evidence base from research, but it is also undesirable from a variety of perspectives and desired outcomes. In short, we suggest that the most common system for identifying talent is unsubstantiated from both a process and an outcome perspective.
Local Proportional Scaling of Time-Series Data: Method and Applications
Authors: Kanatani-Fujimoto Koichiro , Lazareva Betty V. , Zatsiorsky Vladimir M.
Published: August 2016

A method for analysis of time-series data, local proportional scaling (LPS), is proposed and its applications in motor control and biomechanics are discussed. The method is based on comparison of two time curves: a reference curve x(t) and a test curve x'(t'). By assumption, x'(t') is received from x(t) by local affine transformations, local extensions/compressions along the x and t axes [x(t)→x'(t'), where → stands for the local extensions/compressions along the x and t axes]. The aim of the LPS method is to discover the underlying transformations, including gain indexes, time epochs, velocity quotients, time segments, and time quotients. The LPS method can be used for (a) comparing the time-series curves in a concise transparent manner; (b) scaling the curves, bringing x'(t') in conformity with x(t); (c) automatic segmentation of the time series data; and (d) data classification.
Stepping in Humans with Complete Spinal Cord Transection: A Phylogenetic Evaluation
Authors: Vilensky Joel A. , O'Connor Brian L.
Published: August 2016

In this paper we review the literature on stepping in nonhuman and human primates with complete transection of the spinal cord and consider these data relative to the principle of “encephalization” of motor functions with ascension in phylogeny. We conclude that techniques useful for producing self-generated stepping behavior in nonprimates with complete spinal cord transection may not be successful in humans and other higher primates with complete transection.
On Muscle and Joint Viscosity
Authors: Zatsiorsky Vladimir M.
Published: August 2016

A rather messy situation exists in the motor control literature with the notion of muscle and joint viscosity. The source of the confusion lies in attempts to study human movement using a simple mechanical concept that was proposed for uncomplicated objects such as a gel or gas. Although A.V. Hill (1938) wrote, “The 'viscosity' hypothesis must be dismissed” (p. 193), the concept of muscle/joint viscosity is still very popular in the literature. Distressingly, the reported values of muscle/joint viscosity differ greatly. Eleven dissimilar “viscosities” are briefly discussed. They represent disparate characteristics of the human motion system. It seems that the concept of viscosity is inadequate for describing motor control phenomena.
Impact of the Visual Environment on the Execution of Aimed Movements
Authors: van Doorn Robert R.A. , Unema Pieter J.A.
Published: August 2016

The present study showed that movement execution depends on the direct visual environment. We replicated findings of an earlier study that showed a difference between real time information via a trace of the unfolding trajectory, and cursor feedback constituting real time information about the changing movement location. Detailed analyses involving subdividing a movement into four successive sections revealed that movements governed by trace feedback were typically slower and required more feedback guidance near the occurrence of peak velocity. The present study further showed that movement behavior under the two visual modes diverged even more due to the presence of a static object positioned within the action area of the movement. Movements in the trace feedback condition were affected by the presence of an object in the second half of the movement trajectory when the movement reached peak deceleration. Discussion focuses on the differences between the two modes of online visual information.
Intentional Switches between Bimanual Coordination Patterns Are Primarily Effectuated by the Nondominant Hand
Authors: de Poel Harjo J. , Peper C.E. , Beek Peter J.
Published: August 2016

Based on indications that hand dominance is characterized by asymmetrical interlimb coupling strength (with the dominant hand exerting stronger influences on the nondominant hand than vice versa), intentional switches between rhythmic bimanual coordination patterns were predicted to be mediated primarily by phase adaptations in the movements of the nondominant hand. This hypothesis was supported for both right-handed and left-handed participants who performed voluntary switches from in-phase to antiphase coordination or vice versa, at four different frequencies. In accordance with previous indications that handedness is expressed less consistently in left-handers, the asymmetry between the hands was less pronounced in left-handed than in right-handed participants. The asymmetry was smaller for switches from in-phase to antiphase coordination (i.e., in the direction opposite to spontaneous transitions) than for switches in the reverse direction, suggesting that (the expression of) the handedness-related asymmetry in coupling strength was weakened by intentional processes associated with these switches.
Does the Capacity to Appropriately Stabilize Trunk Movements Facilitate the Control of Upright Standing?
Authors: Genthon N. , Rougier P.
Published: August 2016

This study was aimed at assessing the possible relationship between upright and sitting postures in healthy adults. The center of pressure trajectories from the force platform on which the subjects stood or sat were analyzed through a frequency analysis and modeled through the fractional Brownian motion framework. The same type of control process was involved during sitting and upright posture maintenance. Both upright and sitting posture would be controlled by the same mechanical law and/or by the same type of central process. Conversely, these two postures presented different characteristics and a relative independence. Both postures displayed specific biomechanical constraints and involved specific effectors, in particular along the anterior-posterior axis. Thus, performances in these two postures are completely independent in the anterior-posterior axis, whereas they are slightly linked in the medio-lateral axis. Improved trunk functions to improve postural stability have an interest solely to improve lateral stabilization.
Changes in the Soleus Stretch Reflex at Different Pedaling Frequencies and Crank Loads during Pedaling
Authors: Larsen Birgit , Voigt Michael , Grey Michael J.
Published: August 2016

The influence of pedaling frequency and crank load on the sensitivity of the soleus short latency stretch reflex (SLR) was examined in nine healthy subjects during pedaling by the use of a custom-built robotic actuator. The SLR decreased successively in downstroke when pedaling frequency increased from 20 to 40 and 60 revolutions per minute at a constant crank load (p = .005). The SLR was unchanged at crank load increases of 2.6 or 5.1 Nm at a constant pedaling frequency (p > .05). Accordingly, it was shown that increased muscle activation level as a consequence of added crank load and increased movement speed does not increase the sensitivity of the soleus SLR.
Effect of Chair Design on Feed-Forward Postural Control in Sitting
Authors: Shenoy Swati , Aruin Alexander S.
Published: August 2016

The objective of this study was to determine if a forward-tilted seat and the resultant semi-kneeling body position associated with sitting on the Balans Multi Chair (BMC) affect postural control in sitting. Nine healthy subjects were seated on either the BMC or a regular (REG) chair with their arms extended. They were instructed to induce self-initiated body perturbations in four different directions by exerting brief pulses of force against a stationary frame positioned in front of them. Electromyographic (EMG) activities of trunk and leg muscles were recorded before and during the perturbations. The results show that sitting on both types of chairs was associated with anticipatory activation of trunk and upper leg muscles. In contrast, anticipatory activation of distal muscles was observed while sitting only on the REG chair and was absent while sitting on the BMC. The outcome of the study suggests that although the forward-tilting seat and semi-kneeling body position might help in preserving a normal lordosis, it is not associated with anticipatory activation of lower leg muscles, which might reduce the ability of an individual to counteract self-initiated body perturbations. These findings stress the important role of chair designs in the control of sitting posture.
Effects of Fatigue on Intermuscular Coordination during Repetitive Hammering
Authors: Côté Julie N. , Feldman Anatol G. , Mathieu Pierre A. , Levin Mindy F.
Published: August 2016

Fatigue affects the capacity of muscles to generate forces and is associated with characteristic changes in EMG signals. It may also influence interjoint and intermuscular coordination. To understand better the global effects of fatigue on multijoint movement, we studied movement kinematics and EMG changes in healthy volunteers asked to hammer repetitively. Movement kinematics and the activity of 20 muscles of the arm, trunk, and leg were recorded before and after subjects became fatigued (as measured using a Borg scale). When fatigue was reached, maximal grip strength and elbow range of motion decreased while the EMG amplitude of the contralateral external oblique muscle was increased. Fatigue did not affect shoulder and wrist kinematics or movement frequency. Results suggest that fatigue influences motion at both local and global levels. Specifically, interjoint and intermuscular coordination adapt to compensate for local effects of fatigue and to maintain key movement characteristics, such as the trajectory of the end effector and the movement frequency. Nonlocal compensations may be a focus of future studies of how fatigue affects complex movements such as those typically performed in the workplace.
Response Modes Influence the Accuracy of Monocular and Binocular Reaching Movements
Authors: Heath Matthew , Neely Kristina , Krigolson Olav
Published: August 2016

The authors manipulated the availability of monocular and binocular vision during the constituent planning and control stages of a goal-directed reaching task. Furthermore, trials were completed with or without online limb vision to determine whether monocular- or binocular-derived ego-motion cues influence the integration of visual feedback for online limb corrections. Results showed that the manipulation of visual cues during movement planning did not influence planning times or overall kinematics. During movement execution, however, binocular reaches—and particularly those completed with online limb vision—demonstrated heightened endpoint accuracy and stability, a finding directly linked to the adoption of a feedback-based mode of reaching control (i.e., online control). In contrast, reaches performed with online monocular vision produced increased endpoint error and instability and demonstrated reduced evidence of feedback-based corrections (i.e., offline control). Based on these results, the authors propose that the combination of static (i.e., target location) and dynamic (i.e., the moving limb) binocular cues serve to specifically optimize online reaching control. Moreover, results provide new evidence that differences in the kinematic and endpoint parameters of binocular and monocular reaches reflect differences in the extent to which the aforementioned engage in online and offline modes of movement control.
An Evaluation of End-Point Trajectory Planning during Skilled Kicking
Authors: Ford Paul , Hodges Nicola J. , Huys Raoul , Williams A. Mark
Published: August 2016

There is evidence that actions are planned by anticipation of their external effects, with the strength of this effect being dependent on the amount of prior practice. In Experiment 1, skilled soccer players performed a kicking task under four conditions: planning in terms of an external action effect (i.e., ball trajectory) or in terms of body movements, either with or without visual error feedback. When feedback was withheld, a ball focus resulted in more accurate outcomes than a body focus. When visual feedback was allowed, there was no difference between these two conditions. In Experiment 2, both skilled and novice soccer players were tested with the addition of a control condition and in the absence of visual feedback. For both groups there was evidence that a ball focus was more beneficial for performance than a body focus, particularly in terms of movement kinematics where correlations across the joints were generally higher for body rather than ball planning. Most skilled participants reported that ball planning felt more normal than body planning. These experiments provide some evidence that actions are planned in terms of their external action effects, supporting the common-coding hypothesis of action planning.
Balance Ability and Muscle Response of the Preferred and Nonpreferred Leg in Soccer Players
Authors: Gstöttner Michaela , Neher Andreas , Scholtz Arne , Millonig Martin , Lembert Sandra , Raschner Christian
Published: August 2016

The aim of this study was to evaluate balance abilities and electromyographic (EMG) latency times of the preferred and nonpreferred leg in soccer players. Whereas side differences between the two legs in force, kicking speed, and joint laxity have been demonstrated in athletes in previous studies, no data are so far available on balance differences. Low balance ability is generally associated with an increased risk of ligament injuries, and the detection of a possible asymmetry in balance is important because a bilateral difference may be a contributing factor to injury. Twenty-one amateur soccer players were tested. Two different balance test instruments were used: the Biodex Stability System and the Tetrax System. For the evaluation of muscle latency times, EMGs were recorded by means of the EquiTest system. None of the tests performed in this study revealed statistically significant differences in balance ability between the preferred and the nonpreferred leg. The investigations of balance function and muscle response in amateur soccer players did not reveal significant differences between the preferred and nonpreferred leg in the current study. However, a certain tendency to better balance in the nonpreferred leg was observed.
Bimanual Coordination of Bowing and Fingering in Violinists—Effects of Position Changes and String Changes
Authors: Kazennikov Oleg , Wiesendanger Mario
Published: August 2016

Music performance is based on demanding motor control with much practice from young age onward. We have chosen to investigate basic bimanual movements played by violin amateurs and professionals. We posed the question whether position and string changes, two frequent mechanisms, may influence the time interval bowing (right)-fingering (left) coordination. The objective was to measure bimanual coordination, i.e., with or without position changes and string changes. The tendency was that the bimanual coordination was statistically only slightly increased or even unchanged but not perceptible. We conclude that the coordination index is limited up to 100 ms intervals, without any erroneous perception. Although the mentioned position changes and string changes are movements with their timing, they are executed in parallel rather than in series with the bow-fingering coordination.
The Use of Auditory Cues in Anticipatory Control of Grasping Forces
Authors: Gonzalez David Antonio , Dubrowski Adam , Carnahan Heather
Published: August 2016

Visual and haptic integration has been examined extensively, however little is known about alternative premovement sensory information to help in the anticipatory control of prehension. This study explored the concept of using auditory cues as an alternative premovement cue. Individuals lifted champagne flutes filled with various levels of water; and one group was given a sound cue before lifting. Sounds provided a precue regarding fluid level and hence mass. Results showed that auditory cues were used to predict the “target force” required to lift the masses, as evidenced by scaling of grip rates as a function of mass in the auditory cue group only. It was hypothesized that individuals used the auditory cues to preprogram the grasping forces produced during the lifting movement.
Intra- and Interpersonal Movement Coordination in Jointly Moving a Rocking Board
Authors: Bosga Jurjen , Meulenbroek Ruud G. J. , Cuijpers Raymond H.
Published: August 2016

In this study, we investigate how two persons (dyads) coordinate their movements when performing cyclical motion patterns on a rocking board. In keeping with the Leading Joint Hypothesis (Dounskaia, 2005), the movement dynamics of the collaborating participants were expected to display features of a prime mover with low movement variability. Fourteen subject pairs performed the task in nine amplitude-frequency combinations that were presented in the form of a to-be-tracked stimulus on a computer display. Participants were asked to track the stimulus by jointly rocking the Board sideways while receiving continuous visual feedback of its rotations. Displacements of 28 IREDS that were attached to the rocking board, both ankles, knees, hips, shoulders and heads of both actors, were sampled at 75 Hz by means of a 3D-motion tracking system. From these data, we derived body-segment angular excursions as well as the continuous relative phase and time-lagged cross-correlations between relevant joint excursions. The results show that, at the intrapersonal level, knee rotations initially led all other joints in time while the antiphase coordination between the knees displayed relative low variability. At the interpersonal level, dyads adopted a leader-follower strategy with respect to the coordination demands of the task. We take that knee rotations create a dynamic foundation at both intra- and interpersonal levels involving subordination of individual action to joint performance thereby allowing for low-dimensional control of joint action in a high-dimensional, repetitive motor task.
High Frequency Sensory Stimulation Improves Tactile but Not Motor Performance in Older Adults
Authors: Voelcker-Rehage Claudia , Godde Ben
Published: August 2016

We examined the effect of high frequency tactile stimulation (tHFS) on tactile and motor performance as well as tactile-motor interactions. Seventeen right-handed participants (66–78 years) underwent a pretest (tactile frequency and spatial discrimination task, manual dexterity test, and precision grip task) with their left hand, received 30 min of tHFS on the tips of their left index finger and thumb, and performed a posttest (control group: no stimulation). Results indicated an improvement in frequency and spatial discrimination in the experimental but not the control group. In the precision grip task, however, training effects as found for the control group seem to be blocked in the experimental group. For the manual dexterity task no effect was found. Our data indicate that tHFS positively influences tactile performance. Assuming tHFS-induced plastic reorganization in somatosensory cortex our results give further evidence to the notion of an interrelation between sensory and motor performance.
Do We Have a “Mental Syllabary” in the Brain? An fMRI Study
Authors: Brendel Bettina , Erb Michael , Riecker Axel , Grodd Wolfgang , Ackermann Hermann , Ziegler Wolfram
Published: August 2016

The present study combines functional magnetic resonance imaging (fMRI) and reaction time (RT) measurements to further elucidate the influence of syllable frequency and complexity on speech motor control processes, i.e., overt reading of pseudowords. Tying in with a recent fMRI-study of our group we focused on the concept of a mental syllabary housing syllable sized ready-made motor plans for high- (HF), but not low-frequency (LF) syllables. The RT-analysis disclosed a frequency effect weakened by a simultaneous complexity effect for HF-syllables. In contrast, the fMRI data revealed no effect of syllable frequency, but point to an impact of syllable structure: Compared with CV-items, syllables with a complex onset (CCV) yielded higher hemodynamic activation in motor “execution” areas (left sensorimotor cortex, right inferior cerebellum), which is at least partially compatible with our previous study. We discuss the role of the syllable in speech motor control.
Arm Motion Coupling During Locomotion-Like Actions: An Experimental Study and a Dynamic Model
Authors: Shapkova E. Yu , Terekhov A.V. , Latash M.L.
Published: August 2016

We studied the coordination of arm movements in standing persons who performed an out-of-phase arm-swinging task while stepping in place or while standing. The subjects were instructed to stop one of the arms in response to an auditory signal while trying to keep the rest of the movement pattern unchanged. A significant increase was observed in the amplitude of the arm that continued swinging under both the stepping and standing conditions. This increase was similar between the right and left arms. A dynamic model was developed including two coupled nonlinear van der Pol oscillators. We assumed that stopping an arm did not eliminate the coupling but introduced a new constraint. Within the model, superposition of two factors, a command to stop the ongoing movement of one arm and the coupling between the two oscillators, has been able to account for the observed effects. The model makes predictions for future experiments.
Strength Training of One Limb Increases Corticomotor Excitability Projecting to the Contralateral Homologous Limb
Authors: Kidgell Dawson J. , Stokes Mark A. , Pearce Alan J.
Published: August 2016

The contralateral transfer of strength following unilateral strength training (ULS) is thought to be due to changes within the nervous system. Using transcranial magnetic stimulation (TMS) we compared corticospinal responses following ULS of the right biceps brachii (BB) projecting to the untrained left BB. Motor evoked potentials (MEPs) were recorded from both BB of 23 individuals pre and post 4 weeks heavy load (80% of 1RM) ULS of right BB. TMS was delivered at intensities below active motor threshold (AMT) to saturation of the MEP (MEPmax). ULS resulted in a 28% increase in 1RM right BB strength, resulting in a 19.2% increase in contralateral strength of the left BB (p = .0001). There was a significant increase in MEP amplitude of 30.3% (p = .03), 33% (p = .05), and 26.5% (p = .01) at AMT, 20% above AMT and MEPmax respectively. No significant differences in silent period were seen at AMT, 20% above AMT or MEPmax. This study has demonstrated increased corticospinal excitability projecting to the untrained arm following heavy load ULS.
Evidence for the Spotting Hypothesis in Gymnasts
Authors: Heinen Thomas
Published: August 2016

The goal of this study was to investigate the visual spotting hypothesis in 10 experts and 10 apprentices as they perform back aerial somersaults from a standing position with no preparatory jumps (short flight duration condition) and after some preparatory jumps with a flight time of 1s (long flight duration condition). Differences in gaze behavior and kinematics were expected between experts and apprentices and between experimental conditions. Gaze behavior was measured using a portable and wireless eye-tracking system in combination with a movement-analysis system. Experts exhibited a smaller landing deviation from the middle of the trampoline bed than apprentices. Experts showed higher fixation ratios during the take-off and flight phase. Experts exhibited no blinks in any of the somersaults in both conditions, whereas apprentices showed significant blink ratios in both experimental conditions. The findings suggest that gymnasts can use visual spotting during the back aerial somersault, even when the time of flight is delimited. We conclude that knowledge about gaze–movement relationships may help coaches develop specific training programs in the learning process of the back aerial somersault.
Facilitation of Nonpreferred Coordination Patterns During the Transition from Discrete to Continuous Movements
Authors: Kostrubiec Viviane , Soppelsa Régis , Albaret Jean-Michel , Zanone Pier-Giorgio
Published: August 2016

This study investigates how motor coordination undergoes the passage from a discrete to a continuous movement régime. Participants repeated concatenated discrete movements with each hand such that one hand was lagging the other by a quarter of a cycle (i.e., with a 90° phase difference). As movement frequency increased, the tendency to persist in this relative phase competed with a progressive effect of the interlimb coupling favoring 0° and 180°. In 61% of the participants, a switch from a discrete to a continuous motion régime was accompanied by a shift toward the 0° or 180°. The 0° was more often favored than 180°. The remaining participants sustained a relative phase close to 90° even at the highest movement frequency and proved to be more accurate at the initial lowest frequency. These findings indicate that a priming effect may circumvent the tendency to produce preferred patterns and favor the production of nonpreferred patterns and that initial individual differences affect how motor coordination evolves with changing constraints.
From Tremor to Movement: Differences in Variability and Coupling During Bilateral Finger Actions
Authors: Morrison S. , Tucker Murray G. , Barrett Rod S.
Published: August 2016

This study examined changes in movement variability, coupling, and muscle activity across three different bilateral finger movements (e.g., postural, isometric, and isotonic). It was predicted that movements characterized by increased interlimb coupling would be associated with increased levels of muscle activity and reduced movement variability. The results demonstrated task-specific differences in interlimb relations with coupling being lowest during postural tasks and highest under isotonic conditions. However, a similar pattern was not observed for muscle activity and movement variability. Of the three tasks, postural tremor movements were more variable and had lower levels of muscle activity. Alternatively, increased muscle activity and more regular movement dynamics were seen under isometric conditions. Overall, it would appear that differences in bilateral coupling across tasks are not reflective of a single driving mechanism but rather reflect differential contribution from intrinsic neuromuscular and mechanical sources.
Trunk Muscle Reflex Amplitudes Increased in Patients With Subacute, Recurrent LBP Treated With a 10-Week Stabilization Exercise Program
Authors: Navalgund Anand , Buford John A. , Briggs Mathew S. , Givens Deborah L.
Published: August 2016

Altered trunk muscle reflexes have been observed in patients with low back pain (LBP). Altered reflexes may contribute to impaired postural control, and possibly recurrence of LBP. Specific stabilization exercise (SSE) programs have been shown to decrease the risk of LBP recurrence in a select group of patients with acute, first episode LBP. It is not known if trunk muscle reflex responses improve with resolution of subacute, recurrent LBP when treated with a SSE program. A perturbation test was used to compare trunk muscle reflexes in patients with subacute, recurrent LBP, before and after 10 weeks of a SSE program and a group of matched control subjects (CNTL). The LBP group pre therapy had delayed trunk muscle reflexes compared with the CNTL group. Post therapy reflex latencies remained delayed, but amplitudes increased. Increased reflex amplitudes could limit excessive movement of the spine when perturbed; potentially helping prevent recurrence.
Drift and Diffusion in Movement Adaptation to Space-Time Constraints
Authors: Liu Yeou-Teh , Hsieh Tsung-Yu , Newell Karl M.
Published: August 2016

Recent studies have shown more than one time scale of change in the movement dynamics of practice. Here, we decompose the drift and diffusion dynamics in adaptation to performing discrete aiming movements with different space-time constraints. Participants performed aiming movements on a graphics drawing board to a point target at 5 different space-time weightings on the task outcome. The drift was stronger the shorter the time constraint whereas noise was U-shaped across the space-time conditions. The drift and diffusion of adaptation in discrete aiming movements varied as a function of the space-time constraints on performance outcome and the spatial, temporal, or space-time measure of performance outcome. The findings support the postulation that the time scale of movement adaptation is task dependent.
Phase Entrainment Strength Scales With Movement Amplitude Disparity
Authors: de Boer Betteco J. , Peper C. (Lieke) E. , Ridderikhoff Arne , Beek Peter J.
Published: August 2016

In the current study, we examined whether coupling influences resulting from unintended afference-based phase entrainment are affected by movement amplitude as such or by the amplitude relation between the limbs. We assessed entrainment strength by studying how passive movements of the contralateral hand influenced unimanual coordination with a metronome. Results showed that amplitude as such did not affect entrainment strength, whereas the amplitude relation between the hands did. Larger amplitudes of the passive hand relative to the active hand resulted in stronger entrainment. This dependence on relative amplitude implies that entrainment strength is not only based on the intensity of afferent signals generated in the entraining limb but also on the susceptibility of the entrained limb to these signals.
Rejecting the Equilibrium-Point Hypothesis
Authors: Gottlieb Gerald L.
Published: August 2016

The lambda version of the equilibrium-point (EP) hypothesis as developed by Feldman and colleagues has been widely used and cited with insufficient critical understanding. This article offers a small antidote to that lack. First, the hypothesis implicitly, unrealistically assumes identical transformations of lambda into muscle tension for antagonist muscles. Without that assumption, its definitions of command variables R, C, and lambda are incompatible and an EP is not defined exclusively by R nor is it unaffected by C. Second, the model assumes unrealistic and unphysiological parameters for the damping properties of the muscles and reflexes. Finally, the theory lacks rules for two of its three command variables. A theory of movement should offer insight into why we make movements the way we do and why we activate muscles in particular patterns. The EP hypothesis offers no unique ideas that are helpful in addressing either of these questions.
On the Problem of Adequate Language in Motor Control
Authors: Gelfand Israel M. , Latash Mark L.
Published: August 2016

An adequate language is a prerequisite for progress in any area of science, including movement science. Notions of structural units and synergies and the principle of minimal interaction are revisited, discussed, and illustrated with a few examples from recent studies. Equilibrium-point hypothesis is considered an example of identifying significant variables in the control of a voluntary movement.
Structural Constraints on the Coordination of Concurrent Rotations of the Head and a Steering Device
Authors: Heuer Herbert , Klein Wolfhard
Published: August 2016

Concurrent movements of different effectors are subject to structural constraints that facilitate certain patterns of coordination but impede others. The constraints for concurrent rotations of the head and a bimanually operated steering device were explored in two experiments. To indicate structural constraints, the difference between concurrent periodic rotations in same and different directions with respect to the variable error of synchronization was used. The first experiment showed less error for rotations in same directions than for rotations in opposite directions. In the second experiment, the same result was obtained with a horizontal and a backward-tilted steering wheel. Adding gaze shifts to head oscillations increased the accuracy of synchronization but did not affect the difference between both coordination patterns. In contrast to the synchronization of head and steering device, the variable error of synchronization of gaze and steering wheel did not differ between both modes of coordination; the error was again reduced when head oscillations were added to the saccades between eccentric fixation targets. This suggests space related (or allocentric) constraints, which most likely originate from concurrent specifications of movement directions in coupled spatiotopic maps so that the specification of rotations in the same direction is facilitated in comparison to rotations in opposite directions.
Cross-Education of Muscle Strength Is Greater with Stimulated than Voluntary Contractions
Authors: Hortobágyi Tibor , Scott Kevin , Lambert Jean , Hamilton George , Tracy James
Published: August 2016

Cross-education enhances the performance of muscles not directly involved in the chronic conditioning of the muscles in a remote limb. Substantial cross-education occurs after training with eccentric contractions or with contractions evoked by electromyostimulation (EMS). Since during EMS and eccentric contractions, skin and muscle afferents are activated that have excitatory effects on contralateral homologous muscles, it was hypothesized that exercise training with stimulated vs. voluntary eccentric contractions would lead to greater cross-education. Thirty-two women were randomly assigned to a voluntary (Vol), an EMS, or a remote EMS (rEMS) exercise group and performed 840 voluntary or stimulated eccentric contractions over 6 weeks. All subjects, including nonexercising controls (Con), were tested pre- and posttraining for maximal voluntary and stimulated isometric and eccentric quadriceps strength. Ipsilateral voluntary and stimulated forces increased in all groups. Changes in EMG activity paralleled those in voluntary force in each limb. No changes occurred in grip strength. The greater contra- and ipsilateral strength gains after EMS training were most likely related to an additive effect of EMS and muscle lengthening.
On Achieving Strong Inference in Prehension Research
Authors: Marteniuk Ronald G. , Bertram Christopher P.
Published: August 2016

Smeets and Brenner have suggested that it may be time to abandon Jeannerod’s “classical approach” to studying human prehension, and have presented a mathematical model as an alternative. We argue that this model provides insufficient grounds for widespread acceptance, and question whether or not such an approach furthers the science of motor control.
Temporal and Spatial Relationship between Reaching and Grasping. Commentary on “A New View on Grasping”
Authors: Wang Jinsung , Stelmach George E.
Published: August 2016

Smeets and Brenner propose a model that attempts to account for the action patterns involved in prehensile behaviors. However, the model does not provide a full account of the available data on temporal and spatial relationships between the transport and grasp components. Predictions from the model in its current form appear to correspond only to experimental results in a very general way.
How Strongly Is Muscle Activity Associated with Joint Moments?
Authors: Caldwell Graham E. , Li Li
Published: August 2016

In this commentary we question whether the relationship between muscle activity and joint moments is the same for natural motor tasks as for controlled experimental situations. An important consideration in this regard is the identification of the correct electromechanical delay (EMD) for comparing EMG and joint moment data. Data from recent cycling studies are used to illustrate the importance of EMD, and how changing task constraints can alter the relation between muscle activity and joint moment balance for bi-articular antagonist pairs.
General Coordination Principles Elucidated by Forward Dynamics: Minimum Fatigue Does Not Explain Muscle Excitation in Dynamic Tasks
Authors: Kautz Steven A. , Neptune Richard R. , Zajac Felix E.
Published: August 2016

The target article presents a framework for coordination of one- and two-joint muscles in a variety of tasks. Static optimization analyses were performed that minimize muscle fatigue, and it is claimed that the predicted muscle forces account for essential features of EMG activity “qualitatively” well. However, static optimization analyses use the observed joint moments, which implicitly assumes that they minimize the total muscle fatigue of the task. We use a forward dynamics (i.e., relationship between muscle forces and the kinematics and kinetics of task performance) modeling approach to show that this assumption does not appear to be true in cycling (which was used as an example task in the target article). Our results challenge the hypothesized coordination framework and the underlying concept that general coordination principles for dynamic tasks can be elucidated using inverse-dynamics-based analyses.