Comparison of two methodological approaches for the mechanical analysis of single-joint isoinertial movement using a customised isokinetic dynamometer*     

Mathieu Plautard  Gaël Guilhem  Vincent Fohanno  Antoine Nordez  Christophe Cornu 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(3):287-302

Compared to isokinetic and isometric tests, isoinertial movements have been poorly used to assess single-joint performance. Two calculation procedures were developed to estimate mechanical performance during single-joint isoinertial movements performed on a customised isokinetic dynamometer. The results were also compared to appreciate the effects of measurement systems and calculation procedures. Five participants performed maximal knee extensions at four levels of resistance (30, 50, 70 and 90% of the one-repetition maximum, 1-RM). Joint angular velocity and torque were assessed from customised isokinetic dynamometer measures (method A) and from weight stack kinematic (method B). Bland–Altman plots and mean percent differences (M_diff) were used to assess the level of agreement for mean and peak angular velocity and torque. A Passing–Bablok regression was performed to compare the angular velocity-angle and torque-angle relationships computed from the two analysis methods. The results showed a high level of agreement for all mechanical parameters (M_diff < 6% for all parameters). No statistically significant differences were observed between methods A and B in terms of angular velocity-angle and torque-angle relationships except at 30% of 1-RM for the torque-angle relationship. Both methodologies provide comparable values of angular velocity and torque, offering alternative approaches to assess neuromuscular function from single-joint isoinertial movements.  相似文献   

Technology and employment: Mass unemployment or job creation? Empirical evidence from European patenting firms     

Vincent Van Roy  Dániel Vértesy  Marco Vivarelli 《Research Policy》2018,47(9):1762-1776

This paper explores the possible job creation effect of innovation activity. We analyze a unique panel dataset covering almost 20,000 patenting firms from Europe over the period 2003–2012. The main outcome from the proposed GMM-SYS estimations is the labor-friendly nature of innovation, which we measure in terms of forward-citation weighted patents. However, this positive impact of innovation is statistically significant only for firms in the high-tech manufacturing sectors, while not significant in low-tech manufacturing and services.  相似文献   

Does self-perceived sleep reflect sleep estimated via activity monitors in professional rugby league athletes?     

Johnpaul Caia  Heidi R. Thornton  Vincent G. Kelly  Tannath J. Scott  Shona L. Halson  Balin Cupples 《Journal of sports sciences》2018,36(13):1492-1496

This study examined agreement between self-perceived sleep and sleep estimated via activity monitors in professional rugby league athletes. 63 athletes, from three separate teams wore actigraphy monitors for 10.3 ± 3.9 days. During the monitoring period, ratings of perceived sleep quality (on a 1–5 and 1–10 Likert scale), and an estimate of sleep duration were recorded daily. Agreement between sleep estimated via activity monitors and self-perceived sleep was examined using mean bias, Pearson correlation (r) and typical error of the estimate (TEE). 641 nights of sleep were recorded, with a very large, positive correlation observed between sleep duration estimated via activity monitors and subjective sleep duration (r = 0.85), and a TEE of 48 minutes. Mean bias revealed subjective sleep duration overestimated sleep by an average of 19.8 minutes. The relationship between sleep efficiency estimated via activity monitors and self-perceived sleep quality on a 1–5 (r = 0.22) and 1–10 Likert scale (r = 0.28) was limited. The outcomes of this investigation support the use of subjective measures to monitor sleep duration in rugby league athletes when objective means are unavailable. However, practitioners should be aware of the tendency of athletes to overestimate sleep duration.  相似文献   

Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent,male players     

Aaron T Scanlan  Jordan L Fox  Nattai R Borges  Anne Delextrat  Tania Spiteri  Vincent J Dalbo 《Journal of sports sciences》2018,36(8):852-860

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.  相似文献   

The role of Lean principles in supporting knowledge management in IT outsourcing relationships     

Yiwei?GongEmail author  Vincent?Blijleven 《知识管理研究与实践》2017,15(4):533-541

Knowledge management (KM) in information technology outsourcing (ITO) is important to the organizations which pursue long-term strategic benefits and innovation. Effective KM mechanism in outsourcing enables both parties to continuously exchange knowledge and promotes collective learning. This paper investigates the role of Lean principles in supporting KM in ITO relationships. Drawn from the knowledge-based view of the firm, knowledge accessing and knowledge integration and utilization are identified as two key KM processes in outsourcing. Three case studies conducted in different service industries with 18 interviews indicate that the two KM processes were supported by four Lean principles: respect for people, continuous improvement, systems thinking, and proactive behavior. Those principles can be implemented with different tools at different organizational levels. This study reveals the relevance between Lean and KM in ITO relationships, which has not been reported by the KM literature. It also provides implications to ITO practitioners for the implementation of Lean principles.  相似文献   

Demographic characteristics of elite Kenyan endurance runners     

Vincent O. Onywera  Robert A. Scott  Michael K. Boit 《Journal of sports sciences》2013,31(4):415-422

Abstract

Kenyan athletes have dominated international distance running in recent years. Explanations for their success include favourable physiological characteristics, which could include favourable genetic endowment, and advantageous environmental conditions. The aim of this study was to compare the demographic characteristics of elite Kenyan runners with those of the general Kenyan population. Questionnaires, administered to 404 elite Kenyan runners specializing in distances ranging from the 800 m to the marathon and 87 Kenyan controls, obtained information on place of birth, language, and distance and method of travel to school. Athletes were separated into two groups according to athletic success: those who competed in international competition and those who competed in national competition. The athletes differed from controls in regional distribution, language, and distance and method of travel to school; athletes also differed from each other with the exception of method of travel to school. Most national and international athletes came from the Rift Valley province (controls 20%, national athletes 65%, international athletes 81%), belonged to the Kalenjin ethnic group (controls 8%, national athletes 49%, international athletes 76%) and Nandi sub-tribe (controls 5%, national athletes 25%, international athletes 44%), and spoke languages of Nilotic origin (controls 21%, national athletes 60%, international athletes 79%). A higher proportion of all athletes ran to school each day (controls 22%, national athletes 73%, international athletes 81%) and covered greater distances. In conclusion, Kenyan runners are from a distinctive environmental background in terms of geographical distribution, ethnicity and travelled further to school, mostly by running. These findings highlight the importance of environmental and social factors in the success of Kenyan runners.  相似文献   

A citation and co-citation analysis of 10 years of KM theory and practices     

Christian?Walter  Vincent?RibièreEmail author 《知识管理研究与实践》2013,11(3):221-229

In a previous issue of Knowledge Management Research & Practice (KMRP), we analysed the content and keywords of all articles published in the first decade of KMRP. With this article, we extend our preliminary analysis to the citation and co-citations made by these articles. The study covers all the 256 articles published. The most cited article was A dynamic theory of organisational knowledge creation by Nonaka. The most cited KMRP article was by Nonaka and Toyama: The knowledge-creating theory revisited: knowledge creation as a synthesizing process. The co-citation analysis of the 100 most cited articles in KMRP publications showed that four groups of topics emerged, one around communities and situated learning, the second group around networks, knowledge transfer and research methods, a third group around the foundations of knowledge management and a fourth group around intellectual capital.  相似文献   

Body Image Phenomena and Measures of Physiological Performance     

Dr. William J. Vincent  Dr. Don S. Dorsey 《Research quarterly for exercise and sport》2013,84(4):1101-1106

Abstract

This study was designed to investigate the relationships between three measures of body image and two measures of physiological performance. The Fisher-Cleveland Barrier Index, the Secord Homonym Test, and the Body Cathexis Questionnaire were correlated with dominant hand grip strength and the Michael-Gallon revision of the Harvard Step Test. Pearson's r was employed to determine the degree of relationship. Fifty males selected at random from general education classes at San Fernando Valley State College constituted the research sample. Of the six possible pairings only one reached statistical significance: the Homonym Test and grip strength (r = .33 at .05 level). It was concluded that a general relationship does not seem to exist between the measures of body image and physiological performance utilized in this study. These and other findings led the authors to re-examine several questions concerning the nature of body image phenomena.  相似文献   

Investigation of blood pulse PPG signal regulation on toe effect of body posture and lower limb height     

CRABTREE Vincent P.  AZORIN-PERIS Vincent  ECHIADIS Angelos  SMITH Peter R. 《浙江大学学报(A卷英文版)》2007,8(6):916-920

Objective: To study the regulation of blood pulse volume via photoplethysmography (PPG) signal detected from toe, while the lower limb is passively raised in different height positions. Methods: Use a modified non-invasive PPG technique to detect the blood pulse signal on toe with infrared (IR) photo sensor. A protocol consisting of two postures, i.e., supine and 45° reclining, was designed to conduct laboratory trial in this study. During the period of performing the protocol of these postures, the lower limb was passively raised from the heights of 10 cm to 60 cm randomly and individually with sponge blocks underneath the foot. Results: In the supine posture, the higher the foot was passively raised, the more the blood PPG signal decreased. In the 45° reclining posture, the blood PPG signal increased at the beginning and then decreased in the foot height position from 10 cm to 60 cm. In both postures the normalized AC signal changes significantly while the normalized DC signal changes little. Conclusion: The toe PPG signals can obviously indicate the regulated blood volume change with the designated postural procedures due to the heart level position.  相似文献   

Families say 'no' to organ transplants     

Kiernan V 《New scientist (1971)》1995,147(1986):5

  相似文献