bluuebunny/crossref_metadata_2025 huggingface dataset:
Boxing Lessons: An Historical Review of Chronic Head Trauma in Boxing and Football
Authors: Shurley Jason P. , Todd Janice S.
Published: August 2016

In recent years there has been a significant increase in the scrutiny of head trauma in football. This attention is due largely to a host of studies that have been highly publicized and linked the repetitive head trauma in football to late-life neurological impairment. Scientists and physicians familiar with boxing have been aware of such impairment, resulting from repeated head impacts, for more than 80 years. Few, however, made the connection between the similarity of head impacts in boxing and football until recent decades. This article examines the medical and scientific literature related to head trauma in both boxing and football, paying particular attention to the different emphases of that research. Further, the literature is used to trace the understanding of sport-related chronic head trauma as well as how that understanding has prompted reform efforts in each sport. Finally, in light of the current understanding of the long-term sequelae of repetitive head trauma, some consideration is given to what football administrators can learn from the reform efforts in boxing.
Why We Should Care About Diversity in Kinesiology
Authors: Brooks Dana D. , Harrison Louis , Norris Michael , Norwood Dawn
Published: August 2016

The primary purpose of this article is to engage in a dialogue regarding why faculty, students, and administrators should care about diversity and inclusion in kinesiology. Recent American population growth trends data clearly reveals an increase in ethnic minority populations, particularly Hispanics. American public schools and colleges are experiencing greater ethnic diversity, leading to increased diversity within our classrooms. A review of the literature quickly reveals a lack of clarity in defining the terms diversity and inclusion. Throughout the article we define these terms and at the same time identify barriers (on and off campus) to promoting and ensuring a diverse learning environment. Strong arguments are presented supporting the value of diversity within the academy, especially in kinesiology. The value of diversity in kinesiology is refected in scholarly publications, conference programming, awards recognition activities, and in the recruitment and retention of a diverse faculty and student population.
Voluntary and Involuntary Postural Responses to Imposed Optic Flow
Authors: Stoffregen Thomas A. , Hove Philip , Schmit Jennifer , Bardy Benoît G.
Published: August 2016

We demonstrated that postural responses to imposed optic flow are to some extent voluntary. In a moving room, participants either stood normally or were instructed to resist any influence of visible motion on their stance. When participants attempted to resist, coupling of body sway with motion of the room was significantly greater than when the eyes were closed, but was significantly reduced relative to coupling in the normal stance condition. The results indicate that the use of imposed optic flow for postural control is not entirely automatic or involuntary. This conclusion motivates a search for non-perceptual factors that may influence the degree to which body sway is coupled to imposed optic flow.
Differences in Gait between Children with and Without Developmental Coordination Disorder
Authors: Deconinck Frederik J. A. , De Clercq Dirk , Savelsbergh Geert J. P. , Van Coster Rudy , Oostra Ann , Dewitte Griet , Lenoir Matthieu
Published: August 2016

In the present study the walking pattern of 10 children with developmental coordination disorder (DCD) was investigated and compared to that of 10 typically developing, matched control children. All children walked at a similar velocity that was scaled to the length of the leg on a motor-driven treadmill. Three-dimensional kinematics were recorded with a motion capture digital camera system. The spatiotemporal parameters of the gait pattern revealed that children with DCD walked with shorter steps and at a higher frequency than the typically developing children. In addition, the children with DCD exhibited a body configuration that demonstrated increased trunk inclination during the entire gait cycle and enhanced during the entire gait cycle. At toe-off a less pronounced plantar flexion of the ankle was observed in children with DCD. In conclusion, it appeared that children with DCD make adaptations to their gait pattern on a treadmill to compensate for problems with neuromuscular and/or balance control. These adaptations seem to result in a safer walking strategy where the compromise between equilibrium and propulsion is different compared to typically developing children.
Coordination Variability around the Walk to Run Transition during Human Locomotion
Authors: Seay Joseph F. , Haddad Jeffery M. , van Emmerik Richard E.A. , Hamill Joseph
Published: August 2016

Increases in movement variability have previously been observed to be a hallmark property of cooraination changes between coupled oscillators that occur as movement frequency is scaled. Prior research on the walk-run transition in human locomotion has also demonstrated increases in variability around the transition region, supporting predictions of nonequilibrium phase transitions (Diedrich & Warren, 1995). The current study examined the coordinative patterns of both intra- and inter-limb couplings around the walk-run transition using two different temporal manipulations of locomotor velocity as a control parameter in healthy young participants (N = 11). Coordination variability did not increase before the transition. The nature of the change in continuous relative phase variability between gait modes was coupling-specific, and varying the time spent at each velocity did not have an overall effect on gait transition dynamics. Lower extremity inter-limb coordination dynamics were more sensitive to changes in treadmill velocity than intra-limb coordination. The results demonstrate the complexity of segmental coordination change in human locomotion, and question the applicability of dynamical bimanual coordination models to human gait transitions.
Temporal and Spatial Characteristics of Rapid Finger Oscillations
Authors: Heuer Herbert
Published: August 2016

Temporal and spatial movement characteristics are often seen as controlled separately, although they are not independent. Even in the case of simple oscillations mean frequency and mean amplitude covary when one or the other is changed intentionally. The present experiment revealed that in rapid finger oscillations there is also a cycle-to-cycle covariation so that smaller amplitudes are associated with locally increased frequency and (the associated) earlier electromyographic (EMG) bursts. Both globally and locally the observed covariations are consistent with modeling rhythmic movements as output of a driven damped oscillator. The existence of local spatio-temporal covariations suggests limitations for models of timing and reasons for the observation that spatio-temporal movement characteristics cannot be chosen arbitrarily even in uniarticular movements.
Movement Planning in Prehension: Do Intended Actions Influence the Initial Reach and Grasp Movement?
Authors: Armbrüster Claudia , Spijkers Will
Published: August 2016

In three experiments the influence of different consecutive movements on an initial reaching and prehension movement was examined. These so-called after-grasp movements, defined as movements following a prehension movement towards an object, were lifting and raising the object, throwing the object in a bin, and positioning it accurately on a target location. Three different groups of participants (N1 = 8, N2 = 10, N3 = 10) accomplished the lifting and one of the three other after-grasp movements each with three different object sizes and with the left and the right hand. In total, each participant executed 240 trials. Fourteen movement parameter values were examined to analyze the effects of the after-grasp movements on the initial reach and grasp movement. The results showed that movement parameter values of the initial reach and grasp movement were affected differently depending on the type of consecutive movement. In particular, the deceleration phase prior to object contact differed between movement types.
Light Finger Touch on the Upper Legs Reduces Postural Sway during Quasi-Static Standing
Authors: Nagano Akinori , Yoshioka Shinsuke , Hay Dean Charles , Fukashiro Senshi
Published: August 2016

The purpose of this study was to test whether a light finger touch on one’s own body (upper legs) reduces postural sway. Ten healthy males participated. In the first part of the study, the participants stood upright with their eyes closed on a force platform while ground reaction force data were collected. Two conditions differing in the placement of the arms and fingers were tested. In the no-touch condition, the participants kept their hands in loose fists. In the finger-touch condition, the participants lightly touched the lateral sides of the upper legs with all fingers. Postural sway measures were calculated from the ground reaction force data. In the second part of the study, the participants stood upright on a pneumatic balance disk while ground reaction force data were collected. Experimental and measurement protocols were identical to those used in the first part of the study. The results showed that light finger touch on the upper legs significantly reduced postural sway on the balance disk up to ~7%. The data from this study suggest that decreased postural sway due to finger contact may improve balance control during other standing tasks.
Modulation of Anticipatory Postural Adjustments in a Complex Task under Different Temporal Constraints
Authors: Ilmane Nabil , LaRue Jacques
Published: August 2016

The aim of this experiment was to explore the behavioral effects of various temporal pressures on the anticipatory postural adjustments (APAs) in a complex task. Eighteen handball players performed a handball direct throw in three conditions of temporal pressure: (1) a reactive condition (RC), the throw was initiated as quickly as possible following a visual stimulus; (2) an anticipation-coincidence condition (AC), by synchronizing the impact of the ball with the passage of a visual mobile on a target; and (3) a self-initiated (SI) throw. The whole-body postural oscillation and the acceleration of the wrist were measured before and during the throwing action. Results showed that the delays between the onsets of the postural and focal activities were significantly different between RC and both the SI and the AC conditions. Movement time, time to peaks (negative and positive), are shorter in the RC, intermediate in the AC, and longer in the SI condition. Variability was significantly larger in AC in comparison with RC and SI. These results support the existence of different control modes triggered by the temporal pressure; they demonstrate that these control modes can be generalized to complex intentional movements such as the throwing skill and to an anticipation-coincidence situation.
Correlation of Near-Infrared Spectroscopy and Transcranial Magnetic Stimulation of the Motor Cortex in Overt Reading and Musical Tasks
Authors: Lo Y.L. , Zhang H.H. , Wang C.C. , Chin Z.Y. , Fook-Chong S. , Gabriel C. , Guan C.T.
Published: August 2016

In overt reading and singing tasks, actual vocalization of words in a rhythmic fashion is performed. During execution of these tasks, the role of underlying vascular processes in relation to cortical excitability changes in a spatial manner is uncertain. Our objective was to investigate cortical excitability changes during reading and singing with transcranial magnetic stimulation (TMS), as well as vascular changes with nearinfrared spectroscopy (NIRS). Findings with TMS and NIRS were correlated. TMS and NIRS recordings were performed in 5 normal subjects while they performed reading and singing tasks separately. TMS was applied over the left motor cortex at 9 positions 2.5 cm apart. NIRS recordings were made over these identical positions. Although both TMS and NIRS showed significant mean cortical excitability and hemodynamic changes from baseline during vocalization tasks, there was no significant spatial correlation of these changes evaluated with the 2 techniques over the left motor cortex. Our findings suggest that increased left-sided cortical excitability from overt vocalization tasks in the corresponding “hand area” were the result of “functional connectivity,” rather than an underlying “vascular overflow mechanism” from the adjacent speech processing or face/mouth areas. Our findings also imply that functional neurophysiological and vascular methods may evaluate separate underlying processes, although subjects performed identical vocalization tasks. Future research combining similar methodologies should embrace this aspect and harness their separate capabilities.
Anticipatory Postural Adjustments and Focal Performance during Bilateral Forward-Reach Task under Different Stance Conditions
Authors: Yiou Eric , Mezaour Malha , Bozec Serge Le
Published: August 2016

This study investigated how young healthy subjects control their equilibrium in situations of instability specifically elicited by a reduced capacity of force production in the postural muscle system. Ten subjects displaced a bar forward with both hands at maximal velocity toward a target while standing on the dominant leg (UNID), on the nondominant leg (UNIND), or on both legs. In each stance condition, anticipatory postural adjustments (APAs) were elicited. Along the anteroposterior axis, APAs were two-times longer in UNID and UNIND than in bipedal stance, while the anticipatory inertia forces remained equivalent. The focal performance was maintained without any additive postural perturbation. A small effect of leg dominance could be detected on APAs along the mediolateral axis (i.e., anticipatory inertia forces were higher in UNIND than in UNID). These results stress the adaptability of the central nervous system to the instability specifically elicited by reduced postural muscle system efficiency.
Grip Aperture Scaling to Object Size in Chronic Stroke
Authors: Michaelsen Stella Maris , Magdalon Eliane C. , Levin Mindy F.
Published: August 2016

Decreased dexterity in chronic stroke survivors results in diminished hand use and impacts quality of life. We studied reach-and-grasp coordination and aperture scaling during reach to grasp using different grasp types and object sizes (33–55mm). Chronic stroke survivors with hand paresis and controls grasped cylinders with the whole hand or fingertips. Three stroke subjects with more severe hand paresis had disrupted reach/grasp coordination and used compensatory strategies for arm transport and/or grasping. Nine stroke subjects with less severe paresis scaled aperture to cylinder diameter (p < .001) but had slower movements, used excessive trunk movement, and had prolonged deceleration times. Relative time to maximal grip aperture (TMA) occurred earlier in stroke subjects and in both groups when grasping the small cylinder (p < .002). Despite deficits in reach and grasp, chronic stroke survivors with mild to moderate hand paresis may retain grip aperture scaling to object size for different grasp types.
Wrist Muscle Activity during Rapid Unimanual Tapping with a Drumstick in Drummers and Nondrummers
Authors: Fujii Shinya , Kudo Kazutoshi , Shinya Masahiro , Ohtsuki Tatsuyuki , Oda Shingo
Published: August 2016

This study investigated performance and wrist muscle activity during rapid-repetitive unimanual tapping with a drumstick in right-handed drummers and nondrummers. Analyses of performances revealed no difference in tapping frequency and peak tap force between drummers and nondrummers, although the drummers showed less variability in intertap interval than the nondrummers. Analyses of the electromyographic (EMG) data obtained by recording the activity of the flexor carpi ulnalis and the extensor carpi radialis muscles of the right wrist revealed several distinct differences between the two groups: the drummers showed a lower level of muscle cocontraction together with an earlier decline of wrist flexor muscle activity and a smaller variability of muscle activation time in the wrist flexors compared with the nondrummers. We suggest that these characteristics in wrist muscle activity in the drummers have been acquired following extensive practice for the efficient use of wrist muscles and stable drumming performance.
Does Perception Asymmetrically Influence Motor Production in Upper and Lower Visual Fields?
Authors: Brownell K. , Rolheiser T. , Heath M. , Binsted G.
Published: August 2016

The authors examined if previously reported anatomical asymmetries between the upper (uVF) and lower visual fields (lVF) influence the preparation and control of visually and memory-guided reaching movements. To manipulate visual field, participants maintained their visual gaze on a cue position presented above or below the location of a target object, thus resulting in reaches completed in respective uVF and lVF of peripersonal. In Experiment 1, participants performed reaches to four targets with indices of difficulty ranging from 3.1 to 5.1 bits under five visualmemory conditions: full vision and memory-guided conditions entailing 0, 2, 5, and 10 s of delay. In Experiment 2, participants reached to the vertex of Müller-Lyer figures in 3 visual-memory conditions: full vision, and memory-guided conditions entailing 0, and 2 s of delay. In accord with duplex theories of vision (e.g., Milner & Goodale, 1992), it was hypothesized that the introduction of a visual delay and/or the introduction of context-dependent illusory structure would differentially bias the efficiency and effectiveness of uVF and lVF reaches. Although data displayed mixed supported for the existence of an lVF advantage for movement execution, neither the introduction of delay nor contextual illusions succeeded in differentiating visual fields. Thus, performance advantages for movements made in the lower visual field do not appear associated with preferential connections to parietal (i.e., dorsal-action) and temporal (i.e., ventral-perception) architectures.
Motor Abundance Contributes to Resolving Multiple Kinematic Task Constraints
Authors: Gera Geetanjali , Freitas Sandra , Latash Mark , Monahan Katherine , Schöner Gregor , Scholz John
Published: August 2016

This study investigated the use of motor abundance during the transport and placing of objects that required either precise or minimal orientation to the target. Analyses across repetitions of the structure of joint configuration variance relative to the position and orientation constraints were performed using the Uncontrolled Manifold (UCM) approach. Results indicated that the orientation constraint did not affect stability of the hand’s spatial path. Orientation was weakly stabilized during the late transport phase independent of the orientation constraint, indicating no default synergy stabilizing orientation. Stabilization of orientation for conditions most requiring it for successful insertion of the object was present primarily during the adjustment phase. The results support the hypothesis that a major advantage of a control scheme that utilizes motor abundance is the ability to resolve multiple task constraints simultaneously without undue interference among them.
The Effects of Visual Information and Perceptual Style on Static and Dynamic Balance
Authors: Davlin-Pater Christina
Published: August 2016

This study investigated the influence of visual cues and perceptual style on static and dynamic balance performance. Twenty-five field dependent (FD) and twenty-five field independent (FI) participants performed tests of static and dynamic balance under five different vision conditions. Balance performance was measured using the Biodex Balance System. The vision conditions included: eyes open with visual feedback (EOFB), without visual feedback (EOEC), viewing lines tilted 18° (EOTL), eyes open without any visual cues (EONC), and eyes closed (EC). All participants were more stable when visual cues were present. Results revealed no significant difference between the two groups on the static balance task in any of the vision conditions. A significant difference was found between the two groups on the dynamic balance task. In three of the vision conditions (EOFB, EOEC, EOTL), the FI group was found to be more stable than the FD group. Movement of the body required during a dynamic balance task generates vestibular and somatosensory information which FI individuals may be more efficient in translating into greater stability as compared with FD individuals.
Sensory Information Utilization and Time Delays Characterize Motor Developmental Pathology in Infant Sitting Postural Control
Authors: Deffeyes Joan E. , Harbourne Regina T. , Stuberg Wayne A. , Stergiou Nicholas
Published: August 2016

Sitting is one of the first developmental milestones that an infant achieves. Thus measurements of sitting posture present an opportunity to assess sensorimotor development at a young age. Sitting postural sway data were collected using a force plate, and the data were used to train a neural network controller of a model of sitting posture. The trained networks were then probed for sensitivity to position, velocity, and acceleration information at various time delays. Infants with typical development developed a higher reliance on velocity information in control in the anterior-posterior axis, and used more types of information in control in the medial-lateral axis. Infants with delayed development, where the developmental delay was due to cerebral palsy for most of the infants in the study, did not develop this reliance on velocity information, and had less reliance on short latency control mechanisms compared with infants with typical development.
Exploring the Merits of Perceptual Anticipation in the Soccer Penalty Kick
Authors: van der Kamp John
Published: August 2016

This study investigated whether soccer penalty-takers can exploit predictive information from the goalkeeper’s actions. Eight low- and seven high-skilled participants kicked balls in a penalty task with the goalkeeper’s action displayed on a large screen. The goalkeeper initiated his dive either before, at or after the ball was struck. The percentage of balls shot to the empty half of the goal was not above chance when the participants could only rely on predictive information. Gaze patterns suggested that the need to fixate the target location to maintain aiming accuracy hindered perceptual anticipation. It is argued that penalty-takers should select a target location in advance of the run-up to the ball and disregard the goalkeeper’s actions.
Age-Related Changes in Postural Control: Rambling and Trembling Trajectories
Authors: Ferronato Priscilla Augusta Monteiro , Barela José Angelo
Published: August 2016

This study identified and quantified rambling and trembling properties of the postural control system of children 4–12 years of age. Forty five children of varying ages (4-, 8-, and 12-years) and 15 adults stood upright on a force plate and performed 5 trials with and 5 trials without vision with each trial lasting 30 s. Center of pressure, rambling, trembling, mean sway amplitude, and predominant frequency were obtained. Results revealed that the displacement of the center of pressure and overall rambling trajectories were age-related with younger children swaying more than older children and adults. Similarly, overall trembling trajectories for younger children were larger compared with older children and adults. These results suggested that a younger child’s larger body sway mostly results from difficulties using sensory information when estimating overall body position and velocity in an upright stance and is less a result from the noise in the postural control system.
The Influence of Physical Activity, Body Composition, and Lower Extremity Strength on Walking Ability
Authors: Marques Elisa , Carvalho Joana , Pizarro Andreia , Wanderlay Flávia , Mota Jorge
Published: August 2016

We examined the relationship among objective measures of body composition, lower extremity strength, physical activity, and walking performance and determined whether this interaction differed according to walking ability. Participants were 126 adults ages 60–91 yr. Stepwise multiple regression analysis showed that the 30-s chair stand test (30sCST), appendicular lean mass index (aLMI), body mass index, and age were independent contributors to walking performance, explaining 44.3% of the variance. For slower walkers, appendicular fat mass index (aFMI), moderate to vigorous physical activity (MVPA), 30sCST, and aLMI (r2 = .49, p < .001) largely explained variance in walking performance. For faster walkers, aFMI and aLMI explained 31.4% (p < .001) of the variance. These data suggest that both fat and lean mass are associated with walking performance in higher- and lower-functioning older adults, whereas MPVA and muscle strength influence walking ability only among lower-functioning older adults.
Amount of Kinematic Feedback Affects Learning of Speech Motor Skills
Authors: Ballard Kirrie J. , Smith Heather D. , Paramatmuni Divija , McCabe Patricia , Theodoros Deborah G. , Murdoch Bruce E.
Published: August 2016

Knowledge of Performance (KP) feedback, such as biofeedback or kinematic feedback, is used to provide information on the nature and quality of movement responses for the purpose of guiding active learning or rehabilitation of motor skills. It has been proposed that KP feedback may interfere with long-term learning when provided throughout training. Here, twelve healthy English-speaking adults were trained to produce a trilled Russian [r] in words with KP kinematic feedback using electropalatography (EPG) and without KP (noKP). Five one-hour training sessions were provided over one week with testing pretraining and one day and one week posttraining. No group differences were found at pretraining or one day post training for production accuracy. A group by time interaction supported the hypothesis that providing kinematic feedback continually during skill acquisition interferes with retention.
Grip Type and Task Goal Modify Reach-to-Grasp Performance in Post-Stroke Hemiparesis
Authors: Schaefer Sydney Y. , DeJong Stacey L. , Cherry Kendra M. , Lang Catherine E.
Published: August 2016

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in poststroke hemiparesis. Sixteen adults with poststroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared with the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment.
Reduced Cortical Motor Potentials Underlie Reductions in Memory-Guided Reaching Performance
Authors: Krigolson Olav , Bell Jon , Kent Courtney M. , Heath Matthew , Holroyd Clay B.
Published: August 2016

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.
Optic Flow Contribution to Locomotion Adjustments in Obstacle Avoidance
Authors: Menuchi Marcos Rodrigo Trindade Pinheiro , Gobbi Lilian Teresa Bucken
Published: August 2016

Locomotion generates a visual movement pattern characterized as optic flow. To explore how the locomotor adjustments are affected by this pattern, an experimental paradigm was developed to eliminate optic flow during obstacle avoidance. The aim was to investigate the contribution of optic flow in obstacle avoidance by using a stroboscopic lamp. Ten young adults walked on an 8m pathway and stepped over obstacles at two heights. Visual sampling was determined by a stroboscopic lamp (static and dynamic visual sampling). Three-dimensional kinematics data showed that the visual information about self-motion provided by the optic flow was crucial for estimating the distance from and the height of the obstacle. Participants presented conservative behavior for obstacle avoidance under experimental visual sampling conditions, which suggests that optic flow favors the coupling of vision to adaptive behavior for obstacle avoidance.
Effect of Training at Different Body Positions on Proximal and Distal Reaching Adjustments at the Onset of Goal-Directed Reaching: a Controlled Clinical Trial
Authors: Cunha Andréa Baraldi , Soares Daniele A. , Ferro Alyne Montero , Tudella Eloisa
Published: August 2016

The objectives of this study were to verify the influence of a short-duration training session on proximal and distal adjustments at the onset of goal-directed reaching and to verify whether these adjustments change in specificity with the body position trained. Twenty-four infants aged 3–4 months were assessed in supine and reclined during pre and posttraining conditions. During the interval (4 min), 8 infants received reaching training in supine, 8 infants received reaching training in reclined, and 8 infants received no training. The frequencies of reaches, unimanual reaches and reaches with semiopen and oblique hand increased in the posttraining condition for all infants except control infants. Infants trained in the reclined position increased the frequencies of variables in the reclined position. Infants trained in the supine position increased the frequencies of variables in both positions. Few minutes of reaching training are effective to facilitate reaching behavior in infants at the onset of reaching. The effects are specific to the body position trained. As the training in supine requires higher torque to initiate reaching movements, it is more effective to facilitate reaches in both supine and reclined positions.
Tremor Irregularity, Torque Steadiness and Rate of Force Development in Parkinson’s Disease
Authors: Rose Martin H. , Løkkegaard Annemette , Sonne-Holm Stig , Jensen Bente R.
Published: August 2016

We investigated lower-extremity isometric tremor Approximate Entropy (irregularity), torque steadiness and rate of force development (RFD) and their associations to muscle activation strategy during isometric knee extensions in patients with Parkinson’s disease (PD). Thirteen male patients with idiopathic PD and 15 neurologically healthy matched controls performed isometric maximal contractions (extension/flexion) as well as steady submaximal and powerful isometric knee extensions. The patients with PD showed decreased isometric tremor irregularity. Torque steadiness was reduced in PD and the patients had increased muscle coactivation. A markedly lower RFD was found in PD and the decreased RFD correlated with reduced agonist muscle activation. Furthermore, patient RFD correlated with the Movement-Disorder-Society-Unified-Parkinson’s-Disease-Rating-Scale 3 (motor part) scores. We concluded that both knee isometric tremor Approximate Entropy and torque steadiness clearly differentiate between patients with PD and healthy controls. Furthermore, severely compromised RFD was found in patients with PD and was associated with decreased agonist muscle activation.
Orofacial Muscular Activity and Related Skin Movement During the Preparatory and Sustained Phases of Tone Production on the French Horn
Authors: Hirano Takeshi , Kudo Kazutoshi , Ohtsuki Tatsuyuki , Kinoshita Hiroshi
Published: August 2016

This study investigated activity of the embouchure-related orofacial muscles during pre- and postattack phases of sound production by 10 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 formation 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.
Reaching Behavior in Preterm Infants During the First Year of Life: A Systematic Review
Authors: Guimarães Elaine Leonezi , Cunha Andréa Baraldi , Soares Daniele de Almeida , Tudella Eloisa
Published: August 2016

The aim of this systematic literature review was to examine and discuss studies that investigated reaching in preterm infants during the first year of life. Databases were searched using keywords such as reaching, grasping, preterm, and premature, in addition to specific terms from the Medical Subject Headings (MeSH) (motor skills, infant, movement, premature birth, hands) regardless of year of publication. One hundred thirty-five studies were identified, 9 of which were selected. The results showed that preterm infants adopt strategies (bimanual reaches and reaches with less rectilinear trajectories toward an object in motion, reaches with semi-open and open hand, reaches at lower speeds, with increased movement units, and variable postural muscle activity) compared with full-term infants. However, the results on how intrinsic factors (e.g., prematurity) and extrinsic factors (e.g., body position, physical properties of the object) influence early reaching are still limited.
Path Curvature in Workspace and in Joint Space: Evidence for Coexisting Coordinative Rules in Aiming
Authors: Van Thiel Edwin , Meulenbroek Ruud G.J. , Hulstijn Wouter
Published: August 2016

In this study we tried to establish whether point-to-point aiming movements are planned in workspace, joint space, or both. Eight right-handed subjects performed horizontal, vertical, and diagonal aiming movements on a transversal plane. Movements were performed at several speeds. Curvature variations of the hand and corresponding joint-space paths were investigated as a function of position, direction, and speed. Straightness of hand paths predominated for vertical movements but was systematically violated for horizontal and top-right to bottom-left movements. Furthermore, the hand-path curvature of the latter movements increased with speed. Joint-space paths showed more deviation from a straight line than hand paths except for top-left to bottom-right movements in which the paths were equally curved. A comparison of normalized path curvatures at the hand and joint level indicated that in aiming, the coordinative rule of straight-line production seems to apply to both workspace and joint-space planning. The present findings confirm Kawato's (1996) views that optimization processes operate concurrently at the two control levels of arm-trajectory formation under study.
Energy-Minimizing Choices of Muscles and Patterns of Movement
Authors: Alexander R. McNeill
Published: August 2016

Prilutsky (1999, target paper) reports that Crowninshield and Brand's (1981) criterion, minimization of the sum of the cubes of muscle stresses, works well as a predictor of the division of labor between muscles, for various tasks. However, nodirectbenefit from minimizing this particular sum is apparent, and it seems likely that it is merely a correlate of the criterion that actually drives muscle choice. In many tasks, there would be a clear, direct benefit from minimizing metabolic energy costs, as Prilutsky (1999) points out. Alexander (1997a, 1997b) and Minetti and Alexander (1997) have shown how the metabolic energy costs of muscle contraction can be estimated, and used to predict optimum muscle properties or optimal patterns of movement. This article explores the feasibility of using the same approach to predict optimum division of labor between one- and two-joint muscles.
Muscle Coordination: The Discussion Continues
Authors: Prilutsky Boris I.
Published: August 2016

In this response, the major criticisms of the target article are addressed. Terminology from the target article that may have caused some confusion is clarified. In particular, the tasks that have the basic features of muscle coordination, as identified in the target article, have been limited in scope. Anew metabolic optimization criterion suggested by Alexander (2000) is examined for its ability to predict muscle coordination in walking. Issues concerning the validation of muscle force predictions, the rules of muscle coordination, and the role of directional constraints in coordination of two-joint muscles are discussed. It is shown in particular that even in one-joint systems, the forces predicted by the criterion of Crowninshield and Brand (1981) depend upon the muscle moment arms and the physiological cross-sectional areas in much more complex ways than either previously assumed in the target article, or incorrectly derived by Herzog and Ait-Haddou (2000). It is concluded that the criterion of Crowninshield and Brand qualitatively predicts the basic coordination features of the major one- and two-joint muscles in a number of highly skilled, repetitive motor tasks performed by humans under predictable conditions and little demands on stability and accuracy. A possible functional significance of such muscle coordination may be the minimization of perceived effort, muscle fatigue, and/or energy expenditure.
Terrestrial Locomotion in the Black-Billed Magpie. I. Spatio-Temporal Gait Characteristics
Authors: Verstappen Myriam , Aerts Peter
Published: August 2016

Spatio-temporal gait characteristics are determined for walking, running, and out of phase hopping magpies, at velocities ranging from 0.4 to 4 m/s. Below 1 m/s, magpies walk. At higher velocities they either run or hop, the latter being preferred. Stride length and frequency during walking and running relate to speed in an identical way. It is suggested that the control of walking and running, despite the abrupt drop in duty factor and step length at the transition from walking to either running or hopping, is represented by one single intrinsic pattern. Swing phase duration is independent of speed and similar of the three gaits, pointing to a passive, mechanical control. Stride frequencies during hopping barely change with velocity, while its stride length relates to velocity in a way highly comparable to that of walking and running. Hopping step length and duty factor are indifferent from those of running. These facts, combined with the similar spatio-temporal behavior of both legs in hopping suggest fairly comparable intra-limb coordination for running and hopping, and a simple phase-shift in inter-limb coordination to transform a run into a hop.
The Swing Phase of Human Walking Is Not a Passive Movement
Authors: Whittlesey Saunders N. , van Emmerik Richard E.A. , Hamill Joseph
Published: August 2016

Many studies have assumed that the swing phase of human walking at preferred velocity is largely passive and thus highly analogous to the swing of an unforced pendulum. In other words, while swing-phase joint moments are generally nonzero during swing, it was assumed that they were either zero or at least negligibly small compared to gravity. While neglect of joint moments does not invalidate a study by default, it remains that the limitations of such an assumption have not been explored thoroughly. This paper makes five arguments that the swing phase cannot be passive, using both original data and the literature: (1) Computer simulations of the swing phase require muscular control to be accurate. (2) Swing-phase joint moments, while smaller than those during stance, are still greater than those due to gravity. (3) Gravity accounts for a minority of the total kinetics of a swing phase. (4) The kinetics due to gravity do not have the pattern needed to develop a normal swing phase. (5) There is no correlation between pendular swing times and human walking periods in overground walking. The conclusion of this paper is that the swing phase must be an actively controlled process, and should be assumed to be passive only when a study does not require a quantitative result. This conclusion has significant implications for many areas of gait research, including clinical study, control theory, and mechanical modeling.
Role of Different Sensory Inputs for Maintenance of Body Posture in Sitting Rat and Rabbit
Authors: Deliagina Tatiana G. , Beloozerova Irina N. , Popova Ludmila B. , Sirota Mikhail G. , Swadlow Harvey A. , Grant Gunnar , Orlovsky Grigore N.
Published: August 2016

In this paper, we describe the postural activity in sitting rats and rabbits. An animal was positioned on the platform that could be tilted in the frontal plane for up to ±20-30°, and postural corrections were video recorded. We found that in both rat and rabbit, the postural reactions led to stabilization of the dorsal-side-up trunk orientation. The result of this was that the trunk tilt constituted only ~50% (rat) and 25% (rabbit) of the platform tilt. In addition, in the rabbit the head orientation was also stabilized. Trunk stabilization persisted in the animals subjected to the bilateral labyrinthectomy and blindfolding, suggesting that the somatosensory input is primarily responsible for trunk stabilization. Trunk stabilization was due to extension of the limbs on the side moving down, and flexion of the opposite limbs. EMG recordings showed that the limb extension was caused by the active contraction of extensor muscles. We argue that signals from the Golgi tendon organs of the extensor muscles may considerably contribute to elicitation of postural corrective responses to the lateral tilt.
Shoulder and Hand Displacements during Hitting, Reaching, and Grasping Movements in Hemiparetic Cerebral Palsy
Authors: Van Thiel Edwin , Steenbergen Bert
Published: August 2016

In this study, we examined the degree and timing of shoulder displacements during hitting, reaching, and grasping movements performed by young adults with hemiparetic cerebral palsy. The participants performed unimanual and bimanual arm movements towards targets and objects of different sizes. On the basis of the assumption that shoulder displacement due to trunk translation and rotation is a successful, adaptive reaction to reduced joint mobility in the affected arm, the fluency of hand displacements was expected to remain invariant under variations of shoulder displacement as is also the case in healthy participants. The results point in this direction. With respect to the timing of shoulder displacement, prior research suggested that hemiparetic movements can be characterized by inconsistent motion-timing patterns—that is, the timing of shoulder and hand-displacement onsets varied between trials. Therefore, the within-subject variability of the movement-onset asynchrony between hand and ipsilateral shoulder displacement was expected to be larger on the impaired side than on the unimpaired side. This prediction was not confirmed. which challenges these earlier conclusions. Additionally. we also examined the peak-velocity asynchrony of the hand and shoulder. Contrary to the onset asynchrony, the peak asynchrony varied between the hitting and reaching task and between the hitting and grasping task. For the reaching and grasping tasks, there were also significant differences between hands. Again, variability of the (peak-velocity) asynchrony was not significantly increased when comparing the impaired hand with the unimpaired hand. The results suggests that the hemiparetic participants were capable of flexibly recruiting and sequencing the various degrees of freedom of their impaired side required for successful task completion, albeit in different magnitudes and sequenced differently.
Direction of Foot Force for Pushes against a Fixed Pedal: Role of Effort Level
Authors: Gruben Kreg G. , Rogers Lynn M. , Schmidt Matthew W.
Published: August 2016

Control of the force exerted by the foot on the ground is critical to human locomotion. During running on a treadmill and pushing against a fixed pedal, humans increased foot force in a linear manner in sagittal plane force space. However, for pushes against a moving pedal, force output was linear for some participants but slightly curved for others. A primary difference between the static and dynamic pedaling studies was that the dynamic study required participants to push with varying peak effort levels, whereas a constant peak effort level was used for the fixed pedal pushes. The present study evaluated the possibility that force direction varied with level of effort. Seated humans pushed against a fixed pedal to a series of force magnitude targets. The force direction varied systematically with effort level consistent with the force path curvature observed for dynamic pedaling.
Control Strategy for a Hand Balance
Authors: Yeadon Maurice R. , Trewartha Grant
Published: August 2016

The goal of this study was to investigate the control strategy employed by gymnasts in maintaining a hand balance. It was hypothesized that a “wrist strategy” was used in which perturbations in the sagittal plane were corrected using variations in wrist flexor torque with synergistic shoulder and hip torques acting to preserve a fixed body configuration. A theoretical model of wrist strategy indicated that control could be effected using wrist torque that was a linear function of mass center displacement and velocity. Four male gymnasts executed hand balances and 2-dimensional inverse dynamics was used to determine net joint torque time histories at the wrist, shoulder, and hip joints in the sagittal plane. Wrist torque was regressed against mass center position and velocity values at progressively earlier times. It was found that all gymnasts used the wrist strategy, with time delays ranging from 160 to 240 ms. The net joint torques at the shoulder and hip joints were regressed against the torques required to maintain a fixed configuration. This fixed configuration strategy accounted for 86% of the variance in the shoulder torque and 86% of the variance in the hip torque although the actual torques exceeded the predicted torques by 7% and 30%, respectively. The estimated time delays are consistent with the use of long latency reflexes, whereas the role of vestibular and visual information in maintaining a hand balance is less certain.