Richard E A Van Emmerik

University of Massachusetts Amherst, Amherst Center, Massachusetts, United States

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Publications (129)323.88 Total impact

  • Journal of Sports Sciences 11/2015; · 2.25 Impact Factor
  • Source
    Joshua Liddy · Stephanie Jones · Michael A. Busa · Richard E.A. van Emmerik ·

    American Society of Biomechanics, Columbus, OH; 08/2015
  • Jongil Lim · Avelino Amado · Leo Sheehan · Richard E.A. Van Emmerik ·
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    ABSTRACT: Dual-task interference caused by mobile phone use while walking increases safety risks by increasing attentional and cognitive demands. Situational awareness, important for control of walking and safety, has been examined previously but measured only by the awareness of visually noteworthy objects in the environment or the number of times the person looked up from the phone. This study systematically investigated the effects of texting on situational awareness to different environments and its consequent impact on gait kinematics. Twenty healthy volunteers walked on a treadmill while texting and attending to visual tasks simultaneously. Gait parameters and situational awareness examined under dual-task conditions (walk and text or walk, text, and visual task) were compared with those of single-task conditions (text, walk or visual task only). The size of the visual field, display duration of the visual cue, and visual acuity demand were varied across the visual task conditions. About half of the visual cues provided during walking and texting were not perceived (48.3%) as compared to the visual task only condition. The magnitude of this loss of situational awareness was dependent upon the nature of visual information provided. While gait parameters were not different among visual task conditions, greater total medial-lateral excursion of the pelvis was observed in the walk and text condition compared to the walk only condition, showing the dual-task effects of texting on gait kinematics. The study provides further evidence of dual-task effects of texting on situational awareness as well as gait kinematics. Copyright © 2015 Elsevier B.V. All rights reserved.
    Gait & posture 08/2015; 42(4). DOI:10.1016/j.gaitpost.2015.07.060 · 2.75 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the nature of inter-joint coordination at different levels of skilled performance to: (1) distinguish learners who were successful versus unsuccessful in terms of their task performance; (2) investigate the pathways of change during the learning of a new coordination pattern and (3) examine how the learner's coordination patterns relate to those of experts in the longswing gymnastics skill. Continuous relative phase of hip and shoulder joint motions was examined for longswings performed by two groups of novices, successful (n = 4) and unsuccessful (n = 4) over five practice sessions, and two expert gymnasts. Principal component analysis showed that during longswing positions where least continuous relative phase variability occurred for expert gymnasts, high variability distinguished the successful from the unsuccessful novice group. Continuous relative phase profiles of successful novices became more out-of-phase over practice and less similar to the closely in-phase coupling of the expert gymnasts. Collectively, the findings support the proposition that at the level in inter-joint coordination a technique emerges that facilitates successful performance but is not more like an expert's movement coordination. This finding questions the appropriateness of inferring development towards a "gold champion" movement coordination.
    Journal of Sports Sciences 06/2015; DOI:10.1080/02640414.2015.1057209 · 2.25 Impact Factor
  • Jebb G Remelius · Richard E van Emmerik ·
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    ABSTRACT: This study investigated timing and coordination during the swing phase of swing leg, body center of mass (CoM) and head during walking in n=19 people with multiple sclerosis (MS; n=19) and controls (n=19). The MS group showed differences in swing phase timing at all speeds. At imposed but not preferred speeds, the MS group had less time to prepare for entry into the unstable equilibrium, as the CoM entered this phase of swing earlier. Time-to-contact coupling, quantifying the coordination between the CoM and the swing foot, was not different between groups. The projection of head motion on the ground occurred earlier after toe-off and was positioned closer to the body in the MS group, illustrating increased reliance on visual exproprioception in which vision of the body in relation to the surface of support is established. Finally, prospective control, linking head movements to the swing foot time-to-contact and next step landing area, was impaired in the MS group at higher gait speeds.
    Motor control 02/2015; DOI:10.1123/mc.2013-0106 · 1.23 Impact Factor
  • Pedro Rodrigues · Ryan Chang · Trampas TenBroek · Richard van Emmerik · Joseph Hamill ·
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    ABSTRACT: Excessive pronation, because of its coupling with tibial internal rotation (TIR), has been implicated as a risk factor in the development of anterior knee pain (AKP). Traditionally this coupling has been expressed as a ratio between the eversion range of motion and the TIR range of motion (Ev/TIR) that occurs during stance. Currently, this technique has not been used to evaluate specific injuries or the effects of gender. Additionally, Ev/TIR is incapable of detecting coupling changes that occur throughout stance. Therefore, the purpose of this study was to compare the coupling between eversion and TIR in runners with (n = 19) and without AKP (n = 17) and across gender using the Ev/TIR ratio, and more continuously using vector coding. When using vector coding, significant coupling differences were noted in runners with AKP (34-38% stance), with runners with AKP showing relatively more TIR than eversion. Similarly significant differences were noted across gender (14-25 & 36-47% stance) with males transitioning from a loading to propulsive coordination pattern using a proximal to distal strategy, while female runners used a distal to proximal strategy. These differences were only detected when evaluating this coupling relationship using a continuous technique such as vector coding.
    Journal of applied biomechanics 11/2014; 31(2). DOI:10.1123/jab.2014-0067 · 0.98 Impact Factor
  • Richard E A van Emmerik · Stephanie L Jones · Michael A Busa · Jebb G Remelius · Julianna L Averill ·

    Advances in Experimental Medicine and Biology 10/2014; 826:251-76. DOI:10.1007/978-1-4939-1338-1_15 · 1.96 Impact Factor
  • Brittney Cook Muir · Shirley Rietdyk · Jeffrey Haddad · Richard van Emmerik ·

    World Congress of Biomechanics; 07/2014
  • Ryan Chang · Pedro A Rodrigues · Richard E.A. Van Emmerik · Joseph Hamill ·
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    ABSTRACT: Background: Clinically, plantar fasciitis (PF) is believed to be a result and/or prolonged by overpronation and excessive loading, but there is little biomechanical data to support this assertion. The purpose of this study was to determine the differences between healthy individuals and those with PF in (1) rearfoot motion, (2) medial forefoot motion, (3) first metatarsal phalangeal joint (FMPJ) motion, and (4) ground reaction forces (GRF). Methods: We recruited healthy (n=22) and chronic PF individuals (n=22, symptomatic over three months) of similar age, height, weight, and foot shape (p>0.05). Retro-reflective skin markers were fixed according to a multi-segment foot and shank model. Ground reaction forces and three dimensional kinematics of the shank, rearfoot, medial forefoot, and hallux segment were captured as individuals walked at 1.35 ms(-1). Results: Despite similarities in foot anthropometrics, when compared to healthy individuals, individuals with PF exhibited significantly (p<0.05) (1) greater total rearfoot eversion, (2) greater forefoot plantar flexion at initial contact, (3) greater total sagittal plane forefoot motion, (4) greater maximum FMPJ dorsiflexion, and (5) decreased vertical GRF during propulsion. Conclusion: These data suggest that compared to healthy individuals, individuals with PF exhibit significant differences in foot kinematics and kinetics. Consistent with the theoretical injury mechanisms of PF, we found these individuals to have greater total rearfoot eversion and peak FMPJ dorsiflexion, which may put undue loads on the plantar fascia. Meanwhile, increased medial forefoot plantar flexion at initial contact and decreased propulsive GRF are suggestive of compensatory responses, perhaps to manage pain.
    Journal of Biomechanics 06/2014; 47(11). DOI:10.1016/j.jbiomech.2014.06.003 · 2.75 Impact Factor
  • Brittney Cook Muir · Jeffrey Haddad · Shirley Rietdyk · Richard van Emmerik ·

    World Congress of the International Society for Posture and Gait Research; 06/2014
  • J G Remelius · J Hamill · R E A van Emmerik ·
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    ABSTRACT: This study examined the prospective control of the swing phase in young healthy adults while walking at preferred speed over unobstructed ground and during obstacle clearance. Three aspects of swing were examined: (1) the relation of the body Center of Mass (CoM) to the stability boundaries at the base of support; (2) a dynamic time-to-contact analysis of the CoM and swing foot to these boundaries; and (3) the role of head movements in the prospective control of gait and field of view assessment. The time-to-contact analysis of CoM and swing foot showed less stable swing dynamics in the trail foot compared to the lead foot in the approach to the unstable equilibrium, with the CoM leading the swing foot and crossing the anterior stability boundary before the swing foot. Compensations in temporal coupling occurred in the trail limb during the late swing phase. Time-to-contact analysis of head movement showed stronger prospective control of the lead foot, while fixation of the field of view occurred earlier in swing and was closer to the body in the obstacle condition compared to unobstructed walking. The dynamic time-to-contact analysis offers a new approach to assessing the unstable swing phase of walking in different populations.
    Human Movement Science 05/2014; 36. DOI:10.1016/j.humov.2014.04.001 · 1.60 Impact Factor
  • Stephanie L. Jones · Michael A. Busa · Julianna L. Averill · Richard E. A. van Emmerik ·
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    ABSTRACT: The most limiting symptoms reported by individuals with multiple sclerosis (MS) are impaired balance and symptomatic fatigue. We have reported greater postural sway and reduced stability following local muscular fatigue in individuals with MS, suggesting that these symptoms may be related. However, it is unknown whether a similar relationship exists with modest increases in fatigue resulting from an activity of daily living (ADL). Thus, the purpose of this study was to determine whether walking has a greater impact on balance during postural tasks in people with MS (PwMS) compared to those without. Seven PwMS (43±12 yrs, 6F/1M) and 10 controls (CON; 42±12 yrs, 7F/3M) performed postural tasks (quiet stance, fixed/maximal reaches) pre/post 30 minutes of treadmill walking at a range of speeds (0.6-1.4 m/s). Individuals rated their fatigue pre/post walking using a Visual Analog Scale. Kinematic data were recorded using a passive marker system (Qualysis AB) and kinetic data were recorded using two forceplates (AMTI), one under each foot. The net center of pressure was analysed using a time to contact analysis to assess postural stability. Following prolonged walking PwMS demonstrated greater reductions in stability than the CON group during the most challenging task (P=0.04), that may be related to increased fatigue (P
  • Michael A. Busa · Stephanie Jones · Richard van Emmerik ·
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    ABSTRACT: Multiple Sclerosis (MS) is a chronic auto-immune disorder characterized by demyelination of neurons of the central nervous system. MS-related reductions in neural activity have been associated with reductions in balance control and limitations in mobility. Multiscale entropy (MSE) analysis has been used to identify reductions in complexity of the postural control system in various disorders. The purpose of this study was to examine if center-of-pressure fluctuations, analyzed through MSE, differ between persons with MS and healthy controls. We hypothesized that MSE would be reduced in MS compared to controls in all postural tasks in both anterior-posterior (AP) and medio-lateral (ML) directions. Eight persons with MS (7 female, 1 male) and matched controls completed the testing procedures. The MS subjects had minimal functional impairment (Patient Determined Disease Steps, range 0-3). Quiet standing and fixed distance forward and backward reaches were assessed for 30 s. MSE was computed across 30 time scales (range .01-.25s). Effect size (ES) statistics were used to assess differences between MS and control groups. Quiet standing revealed moderate reductions in complexity among persons with MS compared to controls in the AP direction (ES = .71). The backward reach demonstrated moderate and strong reductions in complexity in the AP and ML direction in the MS group (ES = .74 and 1.0, respectively). Moderate reductions in ML complexity were also observed in the forward reach condition in the MS group (ES = .68). These results support the hypothesis that persons with MS display lower postural complexity compared to those without MS. MSE analysis is a promising new tool for detecting MS-related changes in postural complexity. These changes in postural complexity appear to precede locomotor impairment, as assessed by the patient determined disease steps, and may provide novel insight into MS progression.
  • Source
    Joseph F Seay · Richard E A Van Emmerik · Joseph Hamill ·
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    ABSTRACT: Abstract Recent literature has related differences in pelvis-trunk coordination to low back pain (LBP) status. In addition, repetitive motions involving bending and twisting have been linked to high incidence of LBP. The purpose of this study was to examine trunk sagittal motion - axial rotation ('bend and twist') coordination during locomotion in three groups of runners classified by LBP status (LBP: current low back pain; RES: resolved low back pain and CTR: control group with no history of LBP). Trunk kinematic data were collected as running speed was systematically increased on a treadmill. Within-segment coordination between trunk sagittal and transverse planes of motion (trunk lean and axial rotation, respectively) was calculated using continuous relative phase (CRP), and coordination variability was defined as the between stride cycle standard deviation of CRP (CRPvar). Bend-twist coordination was more in-phase for the LBP group than CTR (p = 0.010) regardless of running speed. No differences in CRPvar were found between the groups. The results from our coordination (CRP) analysis were sensitive to LBP status and suggest that multi-plane interactions of the trunk should be considered in the assessment of LBP. This analysis also has potential for athletically oriented tasks that involve multi-plane interactions of the trunk, particularly ones that contain asymmetric action, such as sweep rowing or a shot on goal in field hockey or ice hockey.
    12/2013; 14(6). DOI:10.1080/17461391.2013.866167
  • Christopher J Palmer · Carol Bigelow · Richard E.A. Van Emmerik ·
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    ABSTRACT: Soldier equipment compromises task performance as temporal constraints during critical situations and load increase inertial and interactive forces during movement. Methods are necessary to optimise equipment that relate task performance to underlying coordination and perception-action coupling. Employing ecological task analysis and methods from dynamical systems theory, equipment load and coordination was examined during two sub-tasks embedded in combat performance, threat discrimination and dynamic marksmanship. Perception-action coupling was degraded with load during threat discrimination, leading to delays in functional reaction time. Reduced speed and accuracy during dynamic marksmanship under load was related to disrupted segmental coordination and adaptability during postural transitions between targets. These results show how reduced performance under load relates to coordination changes and perception-action coupling. These changes in functional capability are directly related to soldier survivability in combat. The methods employed may aid equipment design towards more optimised performance by modifying equipment or its distribution on humans. Practitioner Summary: The combat equipment necessary for soldier survival and mission accomplishment significantly impedes task performance. Understanding relations among equipment, task performance, situational awareness and segmental coordination is necessary to define the trade space for design optimisation. This article begins to define this trade space in terms of perception-action coupling and survivability in combat.
    Ergonomics 09/2013; 56(11). DOI:10.1080/00140139.2013.832805 · 1.56 Impact Factor
  • Pedro Rodrigues · Trampas Tenbroek · Richard Van Emmerik · Joseph Hamill ·
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    ABSTRACT: Little biomechanical evidence exists to support the association between excessive foot pronation and anterior knee pain (AKP). One issue could be the way excessive pronation has been defined. Recent evidence has suggested that evaluating pronation in the context of the joint's available range of motion (ROM, anatomical threshold) provides greater insight on when pronation contributes to injury. Theoretically, quantifying the amount of time the joint has to respond before reaching end range (neuromuscular threshold) could provide additional insight. Therefore the purpose of this study was to use a neuromuscular threshold, the time to contact (TtC) the ankle joint complex's ROM boundary, to evaluate runners with and without AKP. Nineteen healthy and seventeen runners with AKP had their ROM and running biomechanics evaluated. The TtC was calculated using each individual's angular distance from end range (eversion buffer) and eversion velocity. Data were recorded over ten stance phases and evaluated using a one way analysis of variance and 95% confidence intervals. Runners with AKP had significantly shorter TtC the joint's ROM boundary when compared to healthy runners (64.0ms vs. 35.6ms, p=0.01). While not statistically significant, this shorter TtC was in large part due to having a smaller eversion buffer, however velocity was found to have a substantial influence on the TtC of select individuals. These results provide evidence that a link between pronation and AKP exists when using anatomical and neuromuscular based thresholds.
    Gait & posture 06/2013; 39(1). DOI:10.1016/j.gaitpost.2013.05.024 · 2.75 Impact Factor
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    ABSTRACT: The aim of this paper was to present a review on the role that movement variability (MV) plays in the analysis of sports movement and in the monitoring of the athlete's skills. MV has been traditionally considered an unwanted noise to be reduced, but recent studies have re-evaluated its role and have tried to understand whether it may contain important information about the neuro-musculo-skeletal organisation. Issues concerning both views of MV, different approaches for analysing it and future perspectives are discussed. Information regarding the nature of the MV is vital in the analysis of sports movements/motor skills, and the way in which these movements are analysed and the MV subsequently quantified is dependent on the movement in question and the issues the researcher is trying to address. In dealing with a number of issues regarding MV, this paper has also raised a number of questions which are still to be addressed.
    Sports Biomechanics 06/2013; 12(2):69-92. DOI:10.1080/14763141.2012.738700 · 1.15 Impact Factor
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    Joseph Hamill · Christopher Palmer · Richard E A Van Emmerik ·
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    ABSTRACT: Overuse injuries are generally defined as a repetitive micro-trauma to tissue. Many researchers have associated particular biomechanical parameters as an indicator of such injuries. However, while these parameters have been reported in single studies, in many instances, it has been difficult to verify these parameters as causative to the injury. We have investigated overuse injuries, such as patella-femoral pain syndrome, using a dynamical systems approach. Using such methods, the importance of the structure of coordinative variability (i.e. the variability of the interaction between segments or joints) becomes apparent. We view coordinative variability as functionally important to the movement and different from end-point or goal variability. Using concepts derived from the work of Bernstein, we conducted studies using a continuous relative phase and/or modified vector coding approaches to investigate the coordinative variability of overuse injuries. Consistently, we have found that the higher variability state of a coordinative structure is the healthy state while the lower variability state is the unhealthy or pathological state. It is clear that very high coordinative variability could also result in injury and that there must be a window of 'higher variability' in which non-injured athletes function. While this finding that coordinative variability is functional has been shown in several studies, it is still not clear if reduced variability contributes to or results from the injury. Studies are currently underway to determine the potential reasons for the reduced variability in injured athletes. Nevertheless, our laboratory believes that this understanding of how joints interact can be important in understanding overuse injuries.
    Sports Medicine Arthroscopy Rehabilitation Therapy & Technology 11/2012; 4(1):45. DOI:10.1186/1758-2555-4-45
  • C.J. Palmer · R.E.A. van Emmerik · J. Hamill ·
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    ABSTRACT: Variability–stability relationships are the very foundation of flexible biological movements. For footwear design, stability is best defined as pattern stability at the level of segmental relationships with regard to goal-oriented performance. Footwear design should seek to optimize the variation in segmental relationships while maintaining the overall locomotion pattern, providing a system that is both adaptable to upcoming events and stable to unanticipated perturbations. As footwear is designed for a variety of uses other than forward, continuous running on a flat terrain, an examination of the fundamental assumptions and applicability of traditional gait dynamics is necessary. Expanding evaluation of gait dynamics to non-forward, non-continuous motion across different terrains would seem appropriate, given the ubiquity of these movements in everyday life. Optimizing footwear design for different tasks requires trade-offs between design and material selection and a principled scientific approach to understanding these trade-offs is required. Evaluation of these non-traditional gait dynamics and incorporation of goal-oriented performance requires consideration of the behavioural consequences of design and perception–action coupling. Understanding variability–stability relationships remains at the center of any attempt to understand footwear performance and design implications in these expanded gait dynamics. The basis for changing historical perspectives on variability–stability relationships is discussed with regard to maintaining and changing coordinative patterns, information–movement relationships, injury prevention, and optimizing performance through footwear design. A principled approach to building a footwear performance space from empirical data is provided, and it is suggested that such an approach offers objective metrics for making appropriate trades in footwear design to optimize performance across categories of intended use.
    Footwear Science 06/2012; 4(2):167-182. DOI:10.1080/19424280.2012.666271
  • Brittney Cook Muir · Jebb Remelius · Richard van Emmerik ·

    Canadian Society of Biomechanics; 06/2012

Publication Stats

2k Citations
323.88 Total Impact Points


  • 1996-2015
    • University of Massachusetts Amherst
      • Department of Kinesiology
      Amherst Center, Massachusetts, United States
  • 2002
    • Microbiology Department at UMass Amherst
      Amherst Center, Massachusetts, United States
  • 1993-1996
    • VU University Amsterdam
      • • Department of Neurology
      • • Faculty of Human Movement Sciences
      Amsterdamo, North Holland, Netherlands
  • 1989-1993
    • University of Illinois, Urbana-Champaign
      • Department of Psychology
      Urbana, Illinois, United States
  • 1992
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands