Maximal heart rate declines linearly with age independent of cardiorespiratory fitness levels     

Cemal Ozemek  Mitchell H. Whaley  W. Holmes Finch  Leonard A. Kaminsky 《European Journal of Sport Science》2017,17(5):563-570

There have been many conflicting observations between the linear or curvilinear decline in maximal heart rate (HR_max) with age. The aim of this study was to determine if linear or curvilinear equations would better describe the decline in HR_max with age in individuals of differing cardiorespiratory fitness (CRF) levels. Treadmill cardiopulmonary exercise test (CPX) results from participants (1510 men and 1134 women; 18–76 years) free of overt cardiovascular disease were retrospectively examined using cross-sectional and longitudinal study designs. Participants completing ≥2 CPX with ≥1 year between test dates were included in the longitudinal analysis (325 men and 150 women). Linear and quadratic regressions were applied to age and HR_max for the whole cohort and respective CRF groups (high, moderate, and low, relative to age and gender normative values). To test for differences among linear, quadratic, and polynomial equations, the change in R² (cross-sectional analysis) and Bayesian information criterion (BIC) (longitudinal analysis) from the linear to the more complex models were calculated. The quadratic or polynomial regression in the cross-sectional analysis, marginally improved the variance in HR_max explained by age compared to the linear regression for the whole cohort (0.2%), moderate fit group (0.3%), and low fit group (0.8%). With no improvements in the high fit group. BIC did not improve for any CRF category in the longitudinal analysis. In conclusion, the minimal differences among linear, quadratic, and polynomial equations in the respective CRF groups, emphasizes the use of linear prediction equations to estimate HR_max.  相似文献   

The validity and reliability of a sample of 10 Wattbike cycle ergometers     

Barney Wainwright  Carlton Brian Cooke  John Paul O’Hara 《Journal of sports sciences》2017,35(14):1451-1458

ABSTRACT

The purpose of the study was to assess the validity and inter-bike reliability of 10 Wattbike cycle ergometers, and to assess the test–retest reliability of one Wattbike. Power outputs from 100 to 1000 W were applied using a motorised calibration rig (LODE) at cadences of 70, 90, 110 and 130 rev · min^?1, which created nineteen different intensities for comparison. Significant relationships (P < 0.01, r² = 0.99) were found between each of the Wattbikes and the LODE. Each Wattbike was found to be valid and reliable and had good inter-bike agreement. Within-bike mean differences ranged from 0.0 W to 8.1 W at 300 W and 3.3 W to 19.3 W at 600 W. When taking into account the manufacturers stated measurement error for the LODE (2%), the mean differences were less than 2%. Comparisons between Wattbikes at each of the nineteen intensities gave differences from 0.6 to 25.5 W at intensities of 152 W and 983 W, respectively. There was no significant difference (P > 0.05) between the measures of power recorded in the test–retest condition. The data suggest that the Wattbike is an accurate and reliable tool for training and performance assessments, with data between Wattbikes being able to be used interchangeably.  相似文献   

Computerized Agility Training Improves Change-of-Direction and Balance Performance Independently of Footwear in Young Adults     

Max R. Paquette  Brian K. Schilling  Joshua D. Bravo  Shelby A. Peel  Yuhua Li  Robert J. Townsend 《Research quarterly for exercise and sport》2017,88(1):44-51

Understanding the effects of training in different footwear on sporting performance would be useful to coaches and athletes. Purpose: This study compared the effects of computerized agility training using 3 types of footwear on change-of-direction and balance performance in young adults. Method: Thirty recreationally active young adults (M_age = 22.8 ± 3.1 years; M_height = 1.71 ± 0.7 m; M_bodymass = 73.4 ± 10.3 kg) were randomly assigned to a 6-week computerized agility training intervention in 1 of 3 footwear groups (n = 10/group): barefoot, minimal footwear, or traditional shoes. Participants had no previous barefoot or minimal-footwear training experience. Dependent variables included change-of-direction test time to completion, Star Excursion Balance Test, and single-leg stability evaluation. Testing was performed at the start of the training program, after 2 weeks, after 4 weeks, and at the end of the training program. Results: No group or time interactions were found for any of the dependent variables. Time main effects were observed for the performance measures of change of direction, Star Excursion, and single-leg-with-eyes-open stability evaluation. Participants improved in all 3 tests as early as 2 weeks into the intervention, with improvements continuing through the entire 6-week intervention. Conclusions: The lack of interaction and footwear effects suggests that agility and balance improvements during foot agility training are independent of footwear in a recreationally active young-adult population. Computerized agility training improves change-of-direction and balance performance within 2 weeks of training implementation. Future studies should consider footwear training effects in different populations, including frail older adults and athletes.  相似文献   

Correction to: Computerized Agility Training Improves Change-of-Direction and Balance Performance Independently of Footwear in Young Adults     

Max R. Paquette  Brian K. Schilling  Joshua D. Bravo  Shelby A. Peel  Yuhua Li  Robert J. Townsend 《Research quarterly for exercise and sport》2017,88(2)

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Boundary-Work in the Health Research Field: Biomedical and Clinician Scientists’ Perceptions of Social Science Research     

Mathieu Albert  Suzanne Laberge  Brian D. Hodges 《Minerva》2009,47(2):171-194

Funding agencies in Canada are attempting to break down the organizational boundaries between disciplines to promote interdisciplinary research and foster the integration of the social sciences into the health research field. This paper explores the extent to which biomedical and clinician scientists’ perceptions of social science research operate as a cultural boundary to the inclusion of social scientists into this field. Results indicated that cultural boundaries may impede social scientists’ entry into the health research field through three modalities: (1) biomedical and clinician scientists’ unfavourable and ambivalent posture towards social science research; (2) their opposition to a resource increase for the social sciences; and (3) clinician scientists procedural assessment criteria for social science. The paper also discusses the merits and limitations of Tom Gieryn’s concept of boundary-work for studying social dynamics within the field of science.

Brian D. HodgesEmail:

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Business communication as cultural text: Exchange and feedback of promotional video clips     

Nurit Zaidman  Prue Holmes   《Int J Intercult Relat》2009,33(6):535-549

Our research is a response to the need to improve the understanding of the complexity of global professional communication. To investigate the complex cultural interpretations that producers and audiences apply to professional texts, we developed a two-year interactive project. Business students in New Zealand and Israel produced promotional “texts” – video clips to promote a university program – which they exchanged with their counterparts overseas to receive feedback. We adapted models of home-made visual communication and advertising which used the categories of participants, settings, topics, and style, to analyze the eight clips. Emergent findings suggested two more categories – information and language – as important analytical tools. Variables of age, gender, intra- and intercultural differences, and (cultural) context also resulted in student audiences’ multiple interpretations of the texts. The outcomes indicate the need to extend the culture-in-context approach for a “situation focused communication approach,” where the primary focus is a group of producers and their audience as they produce and interpret a professional text. This approach also foregrounds contextual variables and a plural understanding of culture to accommodate the potential for miscommunication of business and professional texts in pluricultural contexts.  相似文献   

The spectrophotometric determination of hydrogen-ion concentrations and of the apparent dissociation constants of indicators. II. Thymol blue     

Walter C. Holmes  Edward F. Snyder 《Journal of The Franklin Institute》1925,199(3):417-418

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Sampling analysis and sample size     

M.C. Holmes 《Journal of The Franklin Institute》1935,219(4):483-486

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The detonation wave from solid explosives     

Walter C. Holmes 《Journal of The Franklin Institute》1927,203(4):549-559

It has been shown that the detonation wave from a solid explosive changes in velocity after leaving the explosive. In the case of some low-velocity explosives, e.g., about 2400 metres per second, the velocity of the detonation wave increases by approximately 100–200 metres per second. With other high-velocity explosives, 5000–6000 m./sec., the velocity may decrease to around 4400 metres in some cases.Careful measurements have shown that a zone of uniform velocity exists beyond the surface of the explosive, the dimensions of the zone depending on the diameter of the sphere of the explosive or the diameter of the cartridge detonated. In the case of a $\text{1}\text{1}\text{4}$-inch dynamite cartridge, the zone of uniform velocity extended for about ten inches, while, with a sphere of explosive four inches in diameter, the zone extended for about 25 inches.An explanation of the reason for the high velocity of the detonation wave in the gaseous medium is suggested, linking it up with either the velocity of sound at the temperatures prevailing or the kinetic velocity of the gaseous particles themselves, the latter explanation appearing to be more in accordance with the determined facts. Such an explanation implies the assumption of extremely high momentary temperatures at the wave front, in some cases of over 40,000° C. These extremely high temperatures are due partly to the heat of combustion of the explosive ingredients but more to the heating effect resulting from the enormous pressures developed at the moment of explosion, as previously applied by Berthelot and Dixon in the study of gaseous explosions. Adiabatic conditions are assumed in such calculations. With such an explanation, reasonable agreement between theory and fact is obtained for a number of explosives, and the discrepancies that exist are in cases where discrepancies might be expected.  相似文献   

Bookreviews     

A. D. C. Peterson  Brian Holmes  G. De Landsheere  Helena W. F. Stellwag  Oskar Anweiler  J. O. J. Vanden Bossche  Abraham Robinson  F. I. Calvert  H. H. Stern  J. F. Willatt  Sydney Taylor  M. J. Langeveld  M. A. Brimer  T. N. Postlethwaite  Alexandre Vexliard 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1964,10(1):106-126

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