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Ankle Plantarflexion Strength In Rearfoot And Forefoot Runners: A Novel Clusteranalytic Approach, Dominik Liebl, Steffen Willwacher, Joseph Hamill, Gert-Peter Brüggemann Dec 2013

Ankle Plantarflexion Strength In Rearfoot And Forefoot Runners: A Novel Clusteranalytic Approach, Dominik Liebl, Steffen Willwacher, Joseph Hamill, Gert-Peter Brüggemann

Joseph Hamill

The purpose of the present study was to test for differences in ankle plantarflexion strengths of habitually rearfoot and forefoot runners. In order to approach this issue, we revisit the problem of classifying different footfall patterns in human runners. A dataset of 119 subjects running shod and barefoot (speed 3.5 m/s) was analyzed. The footfall patterns were clustered by a novel statistical approach, which is motivated by advances in the statistical literature on functional data analysis. We explain the novel statistical approach in detail and compare it to the classically used strike index of Cavanagh and Lafortune (1980 ...


Elite Female Tae Kwon Do Athletes Have Faster Reaction Time And Longer Movement Time Than Males During A Striking Kick, Ulysses Fernandes Ervilha, Valmar Fernandes Da Silva, Rubens Correa Araújo, Luis Mochizuki, Joseph Hamill Dec 2013

Elite Female Tae Kwon Do Athletes Have Faster Reaction Time And Longer Movement Time Than Males During A Striking Kick, Ulysses Fernandes Ervilha, Valmar Fernandes Da Silva, Rubens Correa Araújo, Luis Mochizuki, Joseph Hamill

Joseph Hamill

Background & Study Aim: An important aspect of ap bal ap dolio tchagui kick in tae kwon do is that it is usually performed in reaction to a signal or event. That is, given a specific stimulus (i.e. the movement of the opponent), the tae kwon do athlete must react as quickly and accurately as possible to the stimulus. Reacting to a stimulus requires preparation and it is essential to determine this preparation of an elite athlete to perform a task. Therefore, to investigate this movement a reaction time paradigm is appropriate wherein the athlete accomplishes the kick in response to a stimulus. The study investigates the processing, reaction and motor response of male and female athletes in an ecological task. The purpose of this study was to verify the authenticity of the two hypotheses: (1) that the pre-motor time, response time and motor time would the same for males and females; (2) that the magnitudes of the muscle activation would be different between males and females. Materials & Method: The main method is an analysis and comparative study of empirical data. We collected data on 13 Brazilian national calibre tae kwon do athletes (6 male and 7 female) when performing a simple reaction time kicking manoeuvre. The experimental equipment included EMG electrodes placed on six muscles and an electrogoniometer placed on the knee of the kicking limb. Results: We found that pre-motor and response times were faster for females than males for several muscles but the faster movement time for males ...


Acute Effect Of Different Minimalist Shoes On Foot Strike Pattern And Kinematics In Rearfoot Strikers During Running, Roberto Squadrone, Renato Rodano, Joseph Hamill, Ezio Preatoni Dec 2013

Acute Effect Of Different Minimalist Shoes On Foot Strike Pattern And Kinematics In Rearfoot Strikers During Running, Roberto Squadrone, Renato Rodano, Joseph Hamill, Ezio Preatoni

Joseph Hamill

Despite the growing interest in minimalist shoes, no studies have compared the efficacy of different types of minimalist shoe models in reproducing barefoot running patterns and in eliciting biomechanical changes that make them differ from standard cushioned running shoes. The aim of this study was to investigate the acute effects of different footwear models, marketed as “minimalist” by their manufacturer, on running biomechanics. Six running shoes marketed as barefoot/minimalist models, a standard cushioned shoe and the barefoot condition were tested. Foot–/shoe–ground pressure and three-dimensional lower limb kinematics were measured in experienced rearfoot strike runners while they were ...


Coordinative Variability And Overuse Injury, Joseph Hamill, Christopher Palmer, Richard E. A. Van Emmerik Nov 2012

Coordinative Variability And Overuse Injury, Joseph Hamill, Christopher Palmer, Richard E. A. Van Emmerik

Joseph Hamill

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 ...


Evaluation Of The Minimum Energy Hypothesis And Other Potential Optimality Criteria For Human Running, Ross H. Miller, Brian R. Umberger, Joseph Hamill, Graham E. Caldwell Nov 2011

Evaluation Of The Minimum Energy Hypothesis And Other Potential Optimality Criteria For Human Running, Ross H. Miller, Brian R. Umberger, Joseph Hamill, Graham E. Caldwell

Joseph Hamill

A popular hypothesis for human running is that gait mechanics and muscular activity are optimized in order to minimize the cost of transport (CoT). Humans running at any particular speed appear to naturally select a stride length that maintains a low CoT when compared with other possible stride lengths. However, it is unknown if the nervous system prioritizes the CoT itself for minimization, or if some other quantity is minimized and a low CoT is a consequential effect. To address this question, we generated predictive computer simulations of running using an anatomically inspired musculoskeletal model and compared the results with ...


Motor Variability In Sports: A Nonlinear Analysis Of Race Walking, Ezio Preatoni, Manuela Ferrario, Giulia Dona, Joseph Hamill, Renato Rodano Sep 2010

Motor Variability In Sports: A Nonlinear Analysis Of Race Walking, Ezio Preatoni, Manuela Ferrario, Giulia Dona, Joseph Hamill, Renato Rodano

Joseph Hamill

This aim of this study was to analyse the nature of movement variability and to assess whether entropy measures may represent a valuable synthetic index of neuromuscular organization. The regularity of kinematic/kinetic time series during race walking, the changes in the structure of intra-individual variability over the test session, and the influence of athletic skill in (inter)national rank athletes were investigated. Motion analysis techniques were used. Sample entropy (SampEn) was adopted to examine fluctuations in lower limb angles and ground reaction forces. The regularity of both original and surrogate time series was assessed and compared, by estimating SampEn ...


Adjustment To Change In Familiar And Unfamiliar Task Constraints, Ross Sanders, Shuping Li, Joseph Hamill Mar 2009

Adjustment To Change In Familiar And Unfamiliar Task Constraints, Ross Sanders, Shuping Li, Joseph Hamill

Joseph Hamill

The aim of this study was to assess the rate of adjustment to changes in task constraints that are familiar and unfamiliar when a change in the pattern of sequencing of segmental movements is not required. The selected task was underwater flutter kicking with flippers (familiar) and without flippers (unfamiliar). Nine male competitive age-group swimmers were assigned either to an unfamiliar ‘‘leg flipper’’ task, a familiar ‘‘foot flipper’’ task or a ‘‘control’’ group to perform five trials without flippers (all groups), 60 trials with flippers, and a post-test comprising 10 trials without flippers (all groups). Kinematic variables were calculated from ...


Movement Coordination Patterns In Triple Jump Training Drills, Cassie Wilson, Scott Simpson, Joseph Hamill Jan 2009

Movement Coordination Patterns In Triple Jump Training Drills, Cassie Wilson, Scott Simpson, Joseph Hamill

Joseph Hamill

The aim of this study was to determine the effectiveness of training drills in replicating the lower extremity coordination patterns used during the triple jump. Three-dimensional kinematic data and synchronized ground reaction force data were collected during the hop–step transition of a triple jump and four related training drills. Relative motion plots and a modified version of the vector coding technique were used to quantify the coordination patterns of the lower extremities. Differences were observed in the coordination patterns between the triple jump and static drills, but not between the triple jump and dynamic drills, and these differences were ...


In Vivo Lumbo-Sacral Forces And Moments During Constant Speed Running At Different Stride Lengths, Joseph Seay, W. Scott Selbie, Joseph Hamill Nov 2008

In Vivo Lumbo-Sacral Forces And Moments During Constant Speed Running At Different Stride Lengths, Joseph Seay, W. Scott Selbie, Joseph Hamill

Joseph Hamill

The aim of this study was to introduce a Newton–Euler inverse dynamics model that included reaction force and moment estimation at the lumbo-sacral (L5-S1) and thoraco-lumbar (T12-L1) joints. Data were collected while participants ran over ground at 3.8 m s71 at three different stride lengths: preferred stride length, 20% greater than preferred, and 20% less than preferred. Inputs to the model were ground reaction forces, bilateral lower extremity and pelvis kinematics and inertial parameters, kinematics of the lumbar spine and thorax and inertial parameters of the lumbar segment. Repeated measures ANOVA were performed on the lower extremity sagittal ...


Gender Differences In Lower Extremity Coupling Variability During An Unanticipated Cutting Maneuver, Joseph Hamill, Bryan C. Heiderscheit, Christine D. Pollard Apr 2005

Gender Differences In Lower Extremity Coupling Variability During An Unanticipated Cutting Maneuver, Joseph Hamill, Bryan C. Heiderscheit, Christine D. Pollard

Joseph Hamill

The purpose of this study was to determine if gender differences exist in the variability of various lower extremity (LE) segment and joint couplings during an unanticipated cutting maneuver. 3-D kinematics were collected on 24 college soccer players (12 M, 12 F) while each performed the cutting maneuver. The following intralimb couplings were studied: thigh rotation (rot)/leg rot; thigh abduction-adduction/leg abd-add; hip abd-add/knee rot; hip rot/knee abd-add; knee flexion-extension/knee rot; knee flx-ext/hip rot. A vector-coding technique applied to angle-angle plots was used to quantify the coordination of each coupling. The average between-trial standard deviation ...


Issues In Quantifying Variability From A Dynamical Systems Perspective, Joseph Hamill, William J. Mcdermott, Jeffrey M. Haddad Oct 2000

Issues In Quantifying Variability From A Dynamical Systems Perspective, Joseph Hamill, William J. Mcdermott, Jeffrey M. Haddad

Joseph Hamill

Variability is a critical aspect of a dynamical systems analysis. Because there are a number of numerical techniques that can be used in such an analysis, the calculation of variability has several issues that must be addressed. The purpose of this paper is to present a variety of quantitative methods for investigating variability from a dynamical systems perspective. The paper is divided into two major sections covering discrete and continuous methods. Each of these sections is subdivided into two sections. Within discrete methods, we discuss, first, the calculation of the discrete relative phase from a time-series history of two parameters ...