1,721,170 research outputs found
Biomechanics in Paralympic Cross-Country sit skiing: Evidence-based tests for classification
Full text linkThe International Paralympic Committee required the development of a new
evidence-based classification system, by developing measures of performance
and measures of impairment. In cross-country (XC) sit skiing, athletes compete
sitting on a ski-ski and generate propulsion with upper limbs and, when
possible, trunk movements. The purpose of this thesis was to develop a
measure of performance and a measure of impairment of trunk that can be used
for classification purposes. Firstly, biomechanics (maximal speed, generated
force, cycle characteristics, and muscle activation) of skiing on snow and on an
ergometer was compared (article I). The assessment of biomechanics and of
trunk kinematics on the ergometer was used to develop a measure of
performance (article III). Secondly, trunk kinematics during balance test
performed with personal sit-ski was used to propose a measure of impairment
(article II). During the process, a need for a new specific testing device was
identified. A new mechanical system was designed to quantify trunk
kinematics and strength respectively during balance and strength tests.
Collected results allowed developing a measure of trunk impairment that can
be used for classification purposes (article IV). A total of 24 elite XC sit skiers
were recruited. Two separate investigations were completed during the World
Cup: (1) performance tests were conducted on snow and in a laboratory
(articles I, III) and balance tests with personal sit-ski were performed in the
laboratory (article II); (2) strength and balance tests with the new testing device
were performed in the laboratory (article IV). In addition, a cluster analysis was
applied to divide athletes according to their performance and impairment and
to identify the minimum set of parameters that allowed for athletes’ clustering.
Pushing cycle results showed that generated force or maximal speed, together
with cycle time, trunk maximal backward inclination, and trunk range of
motion allowed clustering athletes according to their performance (articles I, III).
Results of balance test and strength test respectively showed that trunk range of
motion and generated force with and without a backrest allowed clustering
athletes according to their impairment (articles II, IV). In conclusion, the
proposed tests and the identified set of parameters may be considered for the
XC sit skiing new evidence-based classification system.
Keywords: performance, adapted ergometer, impairment, strength, trunk
control, spinal cord injuryunknown accessibilityei tietoa saavutettavuudest
Towards Beijing 2022: Discussion on the growth in size of Paralympic Winter Games in terms of participating data from Örnsköldvik 1976 to PyeongChang 2018
Full text linkParalympic Winter Games (PWG) born in 1976. Across Games, media personnel has increased suggesting an increase in PWG size. However, the growth of PWG from Örnsköldsvik 1976 to PyeongChang 2018 in terms of participating data has not been discussed. This work aims to find if the growth in media coverage comes together with an increase in PWG size in terms of National Paralympic Committee, sports, medal events, and athletes. The presence of trend over PWG editions is evaluated with Mann-Kendall Trend Test and differences among sports and continents with Kruskal Wallis test. Showing a significant monotonic trend, the number of countries (p < .001, β = 0.81) and the number of participating athletes (p < .001, β = 7.40) seem to be good indicators of PWG. These two indicators are good descriptors of PWG size because related to sociocultural and political aspects. In contrast, number of medal events being related to many factors did not show statistically significant trend (p = .95); therefore, this indicator seems to be less appropriate to describe PWG size. If the whole history is considered, slow but significant changes in number of sports (p < .001, β = 0.08) suggest this indicator could be considered in describing Games size
Optimization of sEMG electrode positioning in vastus lateralis muscle during neuromuscular electrical stimulation
No full textPurpose: The aim of the study was to estimate spatial activation of vastus lateralis (VL) muscle during electrical stimulation applied to the entire muscle in absence of fatigue and properly eliminating the influence of stimulation artifact.
Methods: Ten healthy men were enrolled in this study. The current was delivered to VL by two electrodes placed proximally and distally, for 5 s at the higher intensity that subjects can tolerate. Superficial electromyography (sEMG) signals were acquired using a bidimensional array of 63 electrodes positioned between the two stimulating electrodes along muscle fibers. For each subjects average rectified value (ARV) was estimated on normalized sEMG signals dividing bidimensional array in two areas, then the barycenter of the more active area was estimated. Finally, average barycenter coordinates were calculated among subjects since Kruskal–Wallis and Dunn-Sidak post hoc test confirmed no statistical differences among subjects in the more active area.
Results: ARV analysis showed that the VL more active area was located laterally and distally with respect to the center of the bidimensional array. Mean and standard deviation among subjects revealed that barycenter of more active zone in medio-lateral direction was between electrodes 1 and 2 and in proximal–distal direction was between electrodes 10 and 11. This location corresponds to a well-defined area in the framework of anatomical landmarks defined in the text.
Conclusions: It was possible to assess that VL during electrical stimulation was activated differently throughout its volume. In particular, distal-lateral portion of the muscle was more active with respect to the other
An agility test to measure performance in Para ice hockey: Test presentation and test-retest reliability
No full textStaggered double-layer array crystals for the reduction of the depth-of-interaction uncertainty in in-beam PET: A preliminary study
No full textWe present a proposal for a PET detector with a specific design oriented to its application to in-beam treatment monitoring in hadron therapy. The design is focused to the reduction of the uncertainty on the depth of the interaction of the gamma rays in the scintillator to improve the final spatial resolution of the reconstructed images. A small detector prototype, based on two staggered scintillator matrices, was assembled and irradiated with a beta(+) emitting radioactive source. The obtained results are presented. (C) 2009 Elsevier B.V. All rights reserved
The Application of sEMG in Aging: A Mini Review
No full textThe aim of this mini-review is to describe the potential application of surface electromyography (sEMG) techniques in aging studies. Aging is characterized by multiple changes of the musculoskeletal system physiology and function. This paper will examine some of the innovative methods used to monitor age-related alterations of the neuromuscular system from sEMG signals. A description of critical assumptions which underlie some of these approaches is emphasized. The first part focuses on the evolution of the recording techniques and describes some methodological issues. The second part focuses on how to use the following techniques to characterize aging: amplitude and spectral sEMG signal analysis, muscle fiber conduction velocity estimation, and myoelectric fatigue assessment. The last part describes a number of advanced sEMG approaches which seem promising in the geriatric population to estimate motor unit number, size, recruitment thresholds, and firing rate
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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