Publications by authors named "John Komar"

17 Publications

  • Page 1 of 1

Physical Activity Measurement Methodologies: A Systematic Review in the Association of South East Asian Nations (ASEAN).

Sports (Basel) 2021 May 20;9(5). Epub 2021 May 20.

National Institute of Education, Nanyang Technological University, Singapore 637616, Singapore.

Non-communicable diseases (NCDs) are a preventable threat to livelihood and longevity in the Association of South East Asian Nations (ASEAN) and insufficient physical activity (PA) is a primary cause of NCDs. A PRISMA-based systematic review of measurement methodologies used to assess PA was conducted. 564 studies published between 1978 and 2020 were reviewed. The majority of the PA measurement employed subjective methodologies and were observational and cross-sectional, with disproportionately fewer studies conducted in economically-challenged member nations, except for Brunei. PA research in Brunei, Cambodia, Laos and Myanmar constituted 0.4-1.1% while Malaysia, Singapore, Thailand and Indonesia contributed 12-37% of all PA research within ASEAN. A decision matrix can be used to determine the measurement methodology of choice to assess PA. Joint research across ASEAN using a common assessment or measurement template that is co-curated by ASEAN researchers that incorporates multi-level and whole-of-society criteria in terms of PA enablers is a recommendation. This could be co-led by more experienced and better-resourced countries so as to produce a unified and universal 'report card' for PA measurement within ASEAN.
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http://dx.doi.org/10.3390/sports9050069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8160759PMC
May 2021

Perceptual-motor skill transfer: Multidimensionality and specificity of both general and specific transfers.

Acta Psychol (Amst) 2021 Jun 3;217:103321. Epub 2021 May 3.

National Institute of Education, Nanyang Technological University, Singapore.

This paper aims to investigate perceptual-motor skill transfer, both through the specific as well as the general aspect of skill transfer. Specifically, we examined differences in skill transfer that occurred between participants who are skilled in practicing a perceptual motor activity involving striking with an implement and participants who are skilled in their own sports but are novice to striking task (i.e., batting an immobile ball). Skill transfer was assessed through the effect of practicing a new, novel task on the performance (ball velocity), intrinsic behavior (elbow and shoulder kinematic) as well as on the impetus for exploratory behavior (variability of elbow and shoulder kinematics) in the two groups of participants (n = 8 for each group), with reference to another group of expert participants (n = 8) for this batting task. Results showed that positive skill transfer was present and was multidimensional in the group of participants who have experience in using an implement in striking tasks. In addition, both specific transfer as well as general transfer were dependent on the task dynamics. More precisely, positive transfer was observed both through a sharing of similar movement patterns, an impetus for exploration and a direct transfer of performance in a novel task between groups who have experience in using an implement in striking tasks.
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http://dx.doi.org/10.1016/j.actpsy.2021.103321DOI Listing
June 2021

Learning and transfer of perceptual-motor skill: Relationship with gaze and behavioral exploration.

Atten Percept Psychophys 2021 Jul 23;83(5):2303-2319. Epub 2021 Mar 23.

Center for the Study and the Transformation of Physical Activities (CETAPS EA3832), Faculty of Sport Sciences, University of Rouen Normandy, UNIROUEN, Mont-Saint-Aignan, France.

Visual and haptic exploration were shown to be central modes of exploration in the development of locomotion. However, it is unclear how learning affects these modes of exploration in locomotor task such as climbing. The first aim of this study was to investigate the modifications of learners' exploratory activity during the acquisition of a perceptual-motor skill. The second aim was to determine to what extent the acquired perceptual-motor skill and the learners' exploratory activity were transferred to environments presenting novel properties. Seven participants attended 10 learning sessions on wall climbing. The effects of practice were assessed during pretest, posttest, and retention tests, each composed of four climbing routes: the route climbed during the learning sessions and three transfer routes. The transfer routes were designed by manipulating either the distance between handholds, the orientation of the handholds or the handholds shape. The results showed that the number of exploratory hand movements and fixations decreased with practice on the learning route. A visual entropy measure suggested that the gaze path in this route became more goal-directed on posttest, but some search was necessary on the retention test. The number of exploratory movements also decreased on the three transfer routes following practice, whereas the number of fixations was higher than on the learning route, suggesting that, with learning, participants relied more on exploration from a distance to adapt to the new properties of the transfer routes. Analyses of the individual performances and behaviors showed differences in the development of skilled exploratory activity.
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http://dx.doi.org/10.3758/s13414-021-02288-zDOI Listing
July 2021

Development of new 9-ball test protocols for assessing expertise in cue sports.

BMC Sports Sci Med Rehabil 2021 Feb 2;13(1). Epub 2021 Feb 2.

Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore, 637616, Singapore.

Background: This study aimed to develop new test protocols for evaluating 9-ball expertise levels in cue sports players.

Methods: Thirty-one male 9-ball players at different playing levels were recruited (recreational group, n = 8; university team, n = 15; national team, n = 8). A 15-ball test was administered to indicate overall performance by counting the number of balls potted. Five skill tests (power control, cue alignment, angle, back spin, and top spin) were conducted to evaluate specific techniques by calculating error distances from pre-set targets using 2D video analysis.

Results: Intra-class correlation analyses revealed excellent intra-rater and inter-rater reliability in four out of five skill tests (ICC > 0.95). Significant between-group differences were found in 15-ball test performance (p <  0.001) and absolute error distances in the angle (p <  0.001), back spin (p = 0.006), and top spin tests (p = 0.045), with the recreational group performing worst while the national team performing best. Greater inter-trial variability was observed in recreational players than the more skilled players (p <  0.005).

Conclusions: In conclusion, the 9-ball test protocols were reliable and could successfully discriminate between different playing levels. Coaches and researchers may employ these protocols to identify errors, monitor training, and rank players.
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http://dx.doi.org/10.1186/s13102-021-00237-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7852083PMC
February 2021

Effects of practice on a mechanical horse with an online feedback on performing a sitting postural coordination.

PLoS One 2020 23;15(10):e0236205. Epub 2020 Oct 23.

Normandie Univ, UNIROUEN, CETAPS, Rouen, France.

The present research aims at quantifying the impact of practicing a new coordination pattern with an online visual feedback on the postural coordination performed on a mechanical horse. Forty-four voluntary participants were recruited in this study. They were randomly assigned to four practice groups based on i) with or without feedback (i.e., group 1, control, did not receive the feedback; group 2, 3 and 4 received an online feedback during practice) and ii) the specific trunk/horse coordination to target during practice (group 1, target coordination = 180° (without feedback); group 2, target coordination = 0°; group 3, target coordination = 90°; group 4, target coordination = 180°). All participants performed pre-, practice, post- and retention sessions. The pre-, post- and retention sessions consisted of four trials, with one trial corresponding to one specific target coordination to maintain between their own oscillations and the horse oscillations (spontaneous, 0°, 90°, and 180°). The practice phase was composed of three different sessions during which participants received an online feedback about the coordination between their own oscillations and the horse oscillations. Results showed a significant change with practice in the trunk/horse coordination patterns which persisted even after one month (retention-test). However, all the groups did not show the same nature of change, evidenced by a high postural variability during post-test for 0° and 90° target coordination groups, in opposition to the 180° and spontaneous groups who showed a decrease in coordination variability for the 180° group. The coordination in anti-phase was characterized as spontaneously adopted by participants on the mechanical horse, explaining the ease of performing this coordination (compared to the 0° and 90° target coordination). The effect of online visual feedback appeared not only on the coordination pattern itself, but most importantly on its variability during practice, including concerning initially stable coordination patterns.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236205PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584198PMC
November 2020

Acute Effect of Exercise on Cognitive Performance in Middle-Aged Adults: Aerobic Versus Balance.

J Phys Act Health 2020 Jul 23:1-8. Epub 2020 Jul 23.

Background: Recent evidence has suggested that chronic physical activities including balance exercises have positive effects on cognition, but their acute effects are still unknown. In the present study, the authors tested the hypothesis that an acute bout of balance exercise would enhance cognitive performance compared with aerobic activity.

Methods: A total of 20 healthy middle-aged adults completed 2 acute 30-minute balance and moderate-intensity aerobic exercise sessions on 2 counterbalanced separate occasions. To assess cognitive functions, performance tasks in executive control, perceptual speed, and simple reaction time were tested before and immediately after each exercise session.

Results: Although there were no significant interactions (time × exercise condition, P > .05), the main effects of time were significant in executive control (P < .05), perceptual speed (P < .05), and simple reaction time (P < .001), showing improvements after both exercises.

Conclusions: These findings highlight that both types of exercise (aerobic, more metabolic and less cognitively demanding; balance, more cognitively and less metabolically demanding) were able to positively affect simple reaction time performance, perceptual speed, and executive control independently of physiological adjustments occurring during aerobic or balance exercise.
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http://dx.doi.org/10.1123/jpah.2020-0005DOI Listing
July 2020

Exploring to learn and learning to explore.

Psychol Res 2021 Jun 10;85(4):1367-1379. Epub 2020 May 10.

Center for the Study and the Transformation of Physical Activities (CETAPS EA3832), Faculty of Sport Sciences, University of Rouen Normandy, UNIROUEN, Mont-Saint-Aignan, France.

In respect to ecological psychology processes of attunement and calibration, this critical review focusses on how exploratory behaviors may contribute to skilled perception and action, with particular attention to sport. Based on the theoretical insights of Gibson (The senses considered as perceptual systems, Houghton Mifflin, Boston, 1966) and Reed (Encountering the world: Toward an ecological psychology, Oxford University Press, New York, 1996), exploratory and performatory actions have been differentiated in numerous experiments to study the perception of opportunities of action. The distinction between exploratory and performatory actions has informed the study of infant behavior in developmental psychology. In the current article, we highlight limitations with this distinction in the study of sports performers. We propose that a dynamic view of exploratory behavior would reveal how individuals develop exploratory activity that generates information about the fit between environmental properties and action capabilities. In this aim, practitioners should: (1) give learners the opportunity to safely develop exploratory behaviors even when they act outside their action boundary; and (2) guide learners to search for more reliable information to develop exploratory behaviors that would enhance the transfer of skills to various performance contexts.
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http://dx.doi.org/10.1007/s00426-020-01352-xDOI Listing
June 2021

Effect of Mechanical Horse Practice as New Postural Training in Patients With Neurological Disorders: A Pilot Study.

Front Psychol 2019 8;10:1035. Epub 2019 May 8.

Normandie Univ, UNIROUEN, CETAPS, Rouen, France.

From a dynamic system approach, this study evaluated the impact of a new training protocol on the postural coordination of brain-damaged patients. Eighteen volunteer brain-damaged patients (i.e., post-stroke or traumatic brain injury) were recruited and randomly divided into an experimental group (horse group; = 10, conventional therapy associated with horse-riding exercise on the mechanical horse for 30 min, twice a week, for 12 weeks) and a control group ( = 8; conventional therapy without intervention on the mechanical horse). Postural coordination was evaluated during pre- and post-tests through discrete relative phase (DRP) computation: ϕ, ϕ A significant effect of used training has been showed, = 16.6 ( < 0.05) for all patients, concerning the trunk/horse coordination. This pilot study results showed the impact of this new training method on the postural coordination of these patients. After 24 sessions, the coordination of the horse group patients differed from that of the control group, showing their ability to adapt to constraints and develop specific modes of postural coordination (trunk/horse ) to optimize their posture.
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http://dx.doi.org/10.3389/fpsyg.2019.01035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6517495PMC
May 2019

Understanding constraints on sport performance from the complexity sciences paradigm: An ecological dynamics framework.

Hum Mov Sci 2017 12 9;56(Pt A):178-180. Epub 2017 May 9.

Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield, United Kingdom.

Glazier's suggestion for the constraints-led approach as a GUT for sport performance is a worthy proposal. What is missing from these preliminary insights is a principled basis, in the form of pillars, for understanding the cornerstones of the sports medicine profession, and this lack of an overarching theoretical framework is also somewhat of a limitation in Glazier's initial ideas, as we argue later. Here we suggest that his preliminary proposal would benefit from considering a more comprehensive ontological positioning within the complexity sciences paradigm to benefit from conceptualising athletes and sports teams as complex adaptive systems. We argue that ecological dynamics provides a more encompassing rationale than the constraint-led approach because it is a multi-dimensional theoretical framework shaped by many relevant disciplines.
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http://dx.doi.org/10.1016/j.humov.2017.05.001DOI Listing
December 2017

Human Energy Expenditure and Postural Coordination on the Mechanical Horse.

J Mot Behav 2017 Jul-Aug;49(4):441-457. Epub 2016 Nov 21.

a CETAPS Laboratory, Faculty of Sports Sciences, University of Rouen, Normandie Université , France.

The authors investigated and compared the energy expenditure and postural coordination of two groups of healthy subjects on a mechanical horse at 4 increasing oscillation frequencies. Energy expenditure was assessed from the oxygen consumption, respiratory quotient, and heart rate values, and postural coordination was characterized by relative phase computations between subjects (elbow, head, trunk) and horse. The results showed that the postural coordination of the riders was better adapted (i.e., maintenance of in-phase and antiphase) than that of the nonriders, but the energy expenditure remains the same. Likewise, we observed an energy system shifting only for nonriders (from aerobic to lactic anaerobic mode). Finally, cross-correlations showed a link between energy expenditure and postural coordination in the riders (i.e., effectiveness).
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http://dx.doi.org/10.1080/00222895.2016.1241743DOI Listing
September 2018

Neurobiological degeneracy: A key property for functional adaptations of perception and action to constraints.

Neurosci Biobehav Rev 2016 Oct 6;69:159-65. Epub 2016 Aug 6.

Centre for Sports Engineering Research, Sheffield Hallam University, Sheffield, UK. Electronic address:

A crucial aspect of understanding human behavior relates to how perception and action sub-systems are integrated during coordinated and controlled movement in goal-directed activity. Here we discuss how a neurobiological system property, degeneracy (i.e., many coordinative structures to achieve one function), can help us understand how skilled individuals functionally adapt perception and action to interacting constraints during performance. Since most research investigating degeneracy has been conducted in neuroanatomy, genetics and theoretical neurobiology, here we clarify how degeneracy is exhibited in perceptual-motor systems. Using an ecological dynamics framework, we highlight how degeneracy underpins the functional role of movement coordination variability in performance of multi-articular tasks. Following that, we discuss how degenerate neurobiological systems are able to exploit system stability and flexibility in their movement coordination. Third, we show how better coupling of information and movement could lead individuals to explore functionally degenerate behaviors. Last, we explore how degeneracy can support pluri-potentiality (i.e., one coordinative structure for many perceptual-motor functions) as a way toward innovation or refinement in performance.
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http://dx.doi.org/10.1016/j.neubiorev.2016.08.006DOI Listing
October 2016

Neurobiological degeneracy: supporting stability, flexibility and pluripotentiality in complex motor skill.

Acta Psychol (Amst) 2015 Jan 26;154:26-35. Epub 2014 Nov 26.

University of Rouen, France.

This paper investigated neurobiological degeneracy of the motor system that emerged as a function of levels of environmental constraint. Fourteen participants performed a breaststroke-swimming task that required them to develop a specific biomechanically expert pattern and in turn provide the basis for a suitable task vehicle to study the functional role of movement variability. Inter-limb coordination was defined based on the computation of continuous relative phase between elbow and knee oscillators. Unsupervised cluster analysis on arm-leg coordination revealed the existence of different patterns of coordination when participants achieved the same task goal under different levels of environmental constraints (i.e. different amounts of forward resistances). In addition, clusters differed in terms of higher order derivatives (e.g., joint angular velocity, joint amplitude), suggesting an effective role for degeneracy in learning by allowing the exploration of the key relationships between motor organization and interacting constraints. There is evidence to suggest that neurobiological degeneracy supports the potential for motor re-organization to enhance motor learning.
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http://dx.doi.org/10.1016/j.actpsy.2014.11.002DOI Listing
January 2015

Coordination pattern adaptability: energy cost of degenerate behaviors.

PLoS One 2014 25;9(9):e107839. Epub 2014 Sep 25.

ISSUL Institute of Sport Sciences - Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.

This study investigated behavioral adaptability, which could be defined as a blend between stability and flexibility of the limbs movement and their inter-limb coordination, when individuals received informational constraints. Seven expert breaststroke swimmers performed three 200-m in breaststroke at constant submaximal intensity. Each trial was performed randomly in a different coordination pattern: 'freely-chosen', 'maximal glide' and 'minimal glide'. Two underwater and four aerial cameras enabled 3D movement analysis in order to assess elbow and knee angles, elbow-knee pair coordination, intra-cyclic velocity variations of the center of mass, stroke rate and stroke length and inter-limb coordination. The energy cost of locomotion was calculated from gas exchanges and blood lactate concentration. The results showed significantly higher glide, intra-cyclic velocity variations and energy cost under 'maximal glide' compared to 'freely-chosen' instructional conditions, as well as higher reorganization of limb movement and inter-limb coordination (p<0.05). In the 'minimal glide' condition, the swimmers did not show significantly shorter glide and lower energy cost, but they exhibited significantly lower deceleration of the center of mass, as well as modified limb movement and inter-limb coordination (p<0.05). These results highlight that a variety of structural adaptations can functionally satisfy the task-goal.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0107839PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177880PMC
June 2015

Nonlinear pedagogy: an effective approach to cater for individual differences in learning a sports skill.

PLoS One 2014 20;9(8):e104744. Epub 2014 Aug 20.

School of Physical Education, Sport and Exercise Sciences, University of Otago, Dunedin, New Zealand.

Learning a sports skill is a complex process in which practitioners are challenged to cater for individual differences. The main purpose of this study was to explore the effectiveness of a Nonlinear Pedagogy approach for learning a sports skill. Twenty-four 10-year-old females participated in a 4-week intervention involving either a Nonlinear Pedagogy (i.e.,manipulation of task constraints including equipment and rules) or a Linear Pedagogy (i.e., prescriptive, repetitive drills) approach to learn a tennis forehand stroke. Performance accuracy scores, movement criterion scores and kinematic data were measured during pre-intervention, post-intervention and retention tests. While both groups showed improvements in performance accuracy scores over time, the Nonlinear Pedagogy group displayed a greater number of movement clusters at post-test indicating the presence of degeneracy (i.e., many ways to achieve the same outcome). The results suggest that degeneracy is effective for learning a sports skill facilitated by a Nonlinear Pedagogy approach. These findings challenge the common misconception that there must be only one ideal movement solution for a task and thus have implications for coaches and educators when designing instructions for skill acquisition.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0104744PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4139301PMC
May 2015

Coordination pattern variability provides functional adaptations to constraints in swimming performance.

Sports Med 2014 Oct;44(10):1333-45

Faculty of Sports Sciences, Centre d'Etude des Transformations des Activités Physiques et Sportives (CETAPS), EA 3832, University of Rouen, Mont Saint Aignan, France,

In a biophysical approach to the study of swimming performance (blending biomechanics and bioenergetics), inter-limb coordination is typically considered and analysed to improve propulsion and propelling efficiency. In this approach, 'opposition' or 'continuous' patterns of inter-limb coordination, where continuity between propulsive actions occurs, are promoted in the acquisition of expertise. Indeed a 'continuous' pattern theoretically minimizes intra-cyclic speed variations of the centre of mass. Consequently, it may also minimize the energy cost of locomotion. However, in skilled swimming performance there is a need to strike a delicate balance between inter-limb coordination pattern stability and variability, suggesting the absence of an 'ideal' pattern of coordination toward which all swimmers must converge or seek to imitate. Instead, an ecological dynamics framework advocates that there is an intertwined relationship between the specific intentions, perceptions and actions of individual swimmers, which constrains this relationship between coordination pattern stability and variability. This perspective explains how behaviours emerge from a set of interacting constraints, which each swimmer has to satisfy in order to achieve specific task performance goals and produce particular task outcomes. This overview updates understanding on inter-limb coordination in swimming to analyse the relationship between coordination variability and stability in relation to interacting constraints (related to task, environment and organism) that swimmers may encounter during training and performance.
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http://dx.doi.org/10.1007/s40279-014-0210-xDOI Listing
October 2014

Do qualitative changes in interlimb coordination lead to effectiveness of aquatic locomotion rather than efficiency?

J Appl Biomech 2014 Apr 22;30(2):189-96. Epub 2013 Jul 22.

CETAPS, EA-3832, Faculty of Sports Sciences, University of Rouen, Rouen, France.

This study compared interlimb coordination and indicators of swim efficiency and effectiveness between expert and recreational breaststroke swimmers. Arm-leg coordination of 8 expert and 10 recreational swimmers at two different paces, slow and sprint, were compared using relative phase between elbow and knee. For each participant, knee and elbow angles were assessed using a 3-dimensional video analysis system with four below and two above cameras. During each phase of the cycle, indicators of swim efficiency (intracyclic velocity variations) and effectiveness (horizontal distance, velocity peaks, acceleration peaks) were calculated. Two coordination patterns emerged between expert and recreational swimmers, with significant differences in the relative phase at the beginning of a cycle (-172.4° for experts and -106.6° for recreational swimmers) and the maximum value of relative phase (9.1° for experts and 45.9° for recreational swimmers; all P<.05). Experts' coordination was associated with higher swim effectiveness (higher acceleration peak: 2.4 m/s2 for experts and 1.6 m/s2 for recreational swimmers) and higher distance covered by the center of mass during each phase of the cycle (all P<.05). This study emphasized how experts coordinate arms and legs to achieve effective behavior, therefore exhibiting flexibility, mainly in the timing of the glide phase, to adapt to different speed.
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http://dx.doi.org/10.1123/jab.2013-0073DOI Listing
April 2014

Automatic front-crawl temporal phase detection using adaptive filtering of inertial signals.

J Sports Sci 2013 5;31(11):1251-60. Epub 2013 Apr 5.

Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Movement Analysis and Measurement, Lausanne, Switzerland.

This study introduces a novel approach for automatic temporal phase detection and inter-arm coordination estimation in front-crawl swimming using inertial measurement units (IMUs). We examined the validity of our method by comparison against a video-based system. Three waterproofed IMUs (composed of 3D accelerometer, 3D gyroscope) were placed on both forearms and the sacrum of the swimmer. We used two underwater video cameras in side and frontal views as our reference system. Two independent operators performed the video analysis. To test our methodology, seven well-trained swimmers performed three 300 m trials in a 50 m indoor pool. Each trial was in a different coordination mode quantified by the index of coordination. We detected different phases of the arm stroke by employing orientation estimation techniques and a new adaptive change detection algorithm on inertial signals. The difference of 0.2 ± 3.9% between our estimation and video-based system in assessment of the index of coordination was comparable to experienced operators' difference (1.1 ± 3.6%). The 95% limits of agreement of the difference between the two systems in estimation of the temporal phases were always less than 7.9% of the cycle duration. The inertial system offers an automatic easy-to-use system with timely feedback for the study of swimming.
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http://dx.doi.org/10.1080/02640414.2013.778420DOI Listing
January 2014
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