Força de preensão – Análise de concordância entre dois dinamómetros: JAMAR vs E‑Link

Introdução – Avaliar a força de preensão mostrou ser de primordial importância pela sua relação com a capacidade funcional dos indivíduos, permitindo determinar níveis de risco para incapacidade futura e, assim, estabelecer estratégias de prevenção. Grande parte dos estudos utiliza o dinamómetro hidráulico JAMAR que fornece o valor da força isométrica obtida durante a execução do movimento de preensão palmar. Contudo, existem outros dinamómetros disponíveis, como é o caso do dinamómetro portátil computorizado E‑Link (Biometrics) que fornece o valor da força máxima (peak force), para além de outras variáveis, como a taxa de fadiga. Não existem, contudo, estudos que nos permitam aceitar e comparar ou não os valores obtidos com os dois equipamentos e porventura utilizá‑los indistintamente. Objetivos – Avaliar a concordância entre as medições da força de preensão (força máxima ou peak force em Kg) obtida a partir de dois equipamentos diferentes (dinamómetros portáteis): um computorizado (E‑Link, Biometrics) e outro hidráulico (JAMAR). Metodologia – Foram avaliados 29 indivíduos (13H; 16M; 22±7 anos; 23,2±3,3 kg/m2) em 2 dias consecutivos, na mesma altura do dia. A posição de teste escolhida foi a recomendada pela Associação Americana de Terapeutas Ocupacionais e foi escolhido o melhor resultado de entre 3 tentativas para a mão dominante. Realizou‑se uma análise correlacional entre os valores obtidos na variável analisada em cada equipamento (coeficiente de Spearman) e uma análise de Bland & Altman para verificar a concordância entre as duas medições. Resultados – O coeficiente de correlação entre as duas medições foi elevado (rS= 0,956; p<0,001) e, pela análise de Bland & Altman, os valores obtidos encontram‑se todos dentro do intervalo da média±2SD. Conclusões – As duas medições mostraram ser concordantes, revelando que os dinamómetros testados podem ser comparáveis ou utilizados indistintamente em diferentes estudos e populações. ABSTRACT: Introduction – Assess grip strength has proved to be of vital importance because of its relationship with functional capacity of individuals, in order to determine levels of risk for future disability and thereby establish prevention strategies. Most studies use the JAMAR Hydraulic dynamometer that provides the value of isometric force obtained during the performance of grip movement. However, there are other dynamometers available, such as portable computerized dynamometer E‑Link (Biometrics), which provides the value of maximum force (peak force) in addition to other variables as the rate of fatigue. There are no studies that allow us to accept or not and compare values obtained with both devices and perhaps use them interchangeably. Purpose – To evaluate the agreement between the measurements of grip strength (peak force or maximum force in kg) obtained from two different devices (portable dynamometers): a computerized (E‑Link, Biometrics) and a hydraulic (JAMAR). Methodology – 29 subjects (13H, 16M, 22 ± 7 years, 23.2 ± 3.3 kg/m2) were assessed on two consecutive days at the same time of day. The test position chosen was recommended by the American Association of Occupational Therapists and was considered the best result from three attempts for the dominant hand. A correlation was studied between values obtained in the variable analyzed in each equipment (Spearman coefficient) and Bland‑Altman analysis to assess the agreement between the two measurements. Results – The correlation coefficient between the two measurements was high (rs = 0,956, p <0,001) and Bland & Altman analysis of the values obtained are all within the range of mean±2SD. Conclusions – The two measurements were shown to be concordant, revealing that the tested dynamometers can be comparable or used interchangeably in different studies and populations.

Grip strength: are dinamometers equivalent? JAMAR vs E-Link

Levels of risk for future disability can be assessed with grip strength. This assessment is of fundamental importance for establishing prevention strategies. It also allows verifying relationships with functional capacity of individuals. Most studies on grip strength use the JAMAR Hydraulic dynamometer that provides the value of isometric force obtained during the performance of grip movement and is considered the “gold standard” for measurement of grip strength. However, there are different dynamometers available commercially, such as portable computerized dynamometer E-Link (Biometrics), which provides the value of maximum force (peak force) in addition to other variables as the rate of fatigue for hand strength, among others. Of our knowledge, there are no studies that allow us to accept or not and compare values obtained with both devices and perhaps use them interchangeably. The aim of this study was to evaluate the absolute agreement between the measurements of grip strength (peak force or maximum force in kg) obtained from two different devices (portable dynamometers): a computerized (E-Link, Biometrics) and one hydraulic (JAMAR).

Reference values for handgrip strength in among healthy young adults

Background: Isometric grip strength, evaluated with a handgrip dynamometer, is a marker of current nutritional status and cardiometabolic risk and future morbidity and mortality. We present reference values for handgrip strength in healthy young Colombian adults (aged 18 to 29 years). Methods: The sample comprised 5.647 (2.330 men and 3.317 women) apparently healthy young university students (mean age, 20.6±2.7 years) attending public and private institutions in the cities of Bogota and Cali (Colombia). Handgrip strength was measured two times with a TKK analogue dynamometer in both hands and the highest value used in the analysis. Sex- and age-specific normative values for handgrip strength were calculated using the LMS method and expressed as tabulated percentiles from 3 to 97 and as smoothed centile curves (P3, P10, P25, P50, P75, P90 and P97). Results: Mean values for right and left handgrip strength were 38.1±8.9 and 35.9±8.6 kg for men, and 25.1±8.7 and 23.3±8.2 kg for women, respectively. Handgrip strength increased with age in both sexes and was significantly higher in men in all age categories. The results were generally more homogeneous amongst men than women. Conclusions: Sex- and age-specific handgrip strength normative values among healthy young Colombian adults are defined. This information may be helpful in future studies of secular trends in handgrip strength and to identify clinically relevant cut points for poor nutritional and elevated cardiometabolic risk in a Latin American population. Evidence of decline in handgrip strength before the end of the third decade is of concern and warrants further investigation

Influence of the tool edge geometry on specific cutting energy at high-speed cutting

This paper presents specific cutting energy measurements as a function of the cutting speed and tool cutting edge geometry. The experimental work was carried out on a vertical CNC machining center with 7,500 rpm spindle rotation and 7.5 kW power. Hardened steels ASTM H13 (50 HRC) were machined at conventional cutting speed and high-speed cutting (HSC). TiN coated carbides with seven different geometries of chip breaker were applied on dry tests. A special milling tool holder with only one cutting edge was developed and the machining forces needed to calculate the specific cutting energy were recorded using a piezoelectric 4-component dynamometer. Workpiece roughness and chip formation process were also evaluated. The results showed that the specific cutting energy decreased 15.5% when cutting speed was increased up to 700%. An increase of 1 °in tool chip breaker chamfer angle lead to a reduction in the specific cutting energy about 13.7% and 28.6% when machining at HSC and conventional cutting speed respectively. Furthermore the workpiece roughness values evaluated in all test conditions were very low, closer to those of typical grinding operations (∼0.20 μm). Probable adiabatic shear occurred on chip segmentation at HSC Copyright © 2007 by ABCM.

Development of a continuum mechanics model of passive skeletal muscle

Skeletal muscle force evaluation is difficult to implement in a clinical setting. Muscle force is typically assessed through either manual muscle testing, isokinetic/isometric dynamometry, or electromyography (EMG). Manual muscle testing is a subjective evaluation of a patient’s ability to move voluntarily against gravity and to resist force applied by an examiner. Muscle testing using dynamometers adds accuracy by quantifying functional mechanical output of a limb. However, like manual muscle testing, dynamometry only provides estimates of the joint moment. EMG quantifies neuromuscular activation signals of individual muscles, and is used to infer muscle function. Despite the abundance of work performed to determine the degree to which EMG signals and muscle forces are related, the basic problem remains that EMG cannot provide a quantitative measurement of muscle force. Intramuscular pressure (IMP), the pressure applied by muscle fibers on interstitial fluid, has been considered as a correlate for muscle force. Numerous studies have shown that an approximately linear relationship exists between IMP and muscle force. A microsensor has recently been developed that is accurate, biocompatible, and appropriately sized for clinical use. While muscle force and pressure have been shown to be correlates, IMP has been shown to be non-uniform within the muscle. As it would not be practicable to experimentally evaluate how IMP is distributed, computational modeling may provide the means to fully evaluate IMP generation in muscles of various shapes and operating conditions. The work presented in this dissertation focuses on the development and validation of computational models of passive skeletal muscle and the evaluation of their performance for prediction of IMP. A transversly isotropic, hyperelastic, and nearly incompressible model will be evaluated along with a poroelastic model.

A compilation of steady state automotive engine test data. Final report.

National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

Manual brake inspection procedures. Volume II. Final technical report.

National Highway Traffic Safety Administration, Office of Vehicle Systems Research, Washington, D.C.

Correlation of braking system defects and performance inspection. Volume II: technical report. Final report.

Mode of access: Internet.

Correlation of braking system defects and performance inspection. Volume I: summary report.

National Highway Traffic Safety Administration, Washington, D.C.

Manual brake inspection procedures. Volume I. Summary report. Final report.

National Highway Traffic Safety Administration, Office of Vehicle Systems Research, Washington, D.C.

The development of a testing procedure for dry friction brakes

A description of the background to testing friction materials for automotive brakes explains the need for a rapid, inexpensive means of assessing their behaviour in a way which is both accurate and meaningful. Various methods of controlling inertia dynamometers to simulate road vehicles are rejected in favour of programming by means of a commercially available XY plotter. Investigation of brake service conditions is used to set up test schedules, and a dynamometer programming unit built to enable service conditions on vehicles to be simulated on a full scale dynamometer. A technique is developed by which accelerated testing can be achieved without operating under overload conditions, saving time and cost without sacrificing validity. The development of programming by XY plotter is described, with a method of operating one XY plotter to programme the machine, monitor its own behaviour, and plot its own results in logical sequence. Commissioning trials are described and the generation of reproducible results in frictional behaviour and material durability is discussed. Teclmiques are developed to cross check the operation of the machine in retrospect, and retrospectively correct results in the event of malfunctions. Sensitivity errors in the measuring circuits are displayed between calibrations, whilst leaving the recorded results almost unaffected by error. Typical results of brake lining tests are used to demonstrate the range of performance parameters which can be studied by use of the machine. Successful test investigations completed on the machine are reported, including comments on behaviour of cast iron drums and discs. The machine shows that materials can repeat their complex friction/ temperature/speed/pressure relationships at a reproducibility of the order of +-0.003u and +~ 0.0002 in. thickness loss during wear tests. Discussion of practical and academic implications completes the report with recommendations for further work in both fields.

Validity and reliability of the international fItness scale (IFIS) in a population-based sample of schoolchildren in Bogota, Colombia: The FUPRECOL study

The International FItness Scale (IFIS) is a self-reported measure of physical fitness that could easily. This scale has been validated in children, adolescents, and young adults; however, it is unknown whether the IFIS represents a valid and reliable estimate of physical fitness in Latino-American youth population. In the present study we aimed to examine the validity and reliability of the IFIS on a population-based sample of schoolchildren in Bogota, Colombia. Participants were 1,875 Colombian youth (56.2% girls) aged 9 to 17.9 years old. We measured adiposity markers (body fat, waist-to-height ratio, skinfold thicknesses and BMI), blood pressure, lipids profile, fasting glucose, and physical fitness level (self reported and measured). Also, a validated cardiometabolic risk index was used. An age- and sex-matched sample of 229 Schoolchildren originally not included in the study sample fulfilled IFIS twice for reliability purposes. Our data suggest that both measured and self-reported overall fitness were associated inversely with adiposity indicators and a cardiometabolic risk score. Overall, schoolchildren who self-reported “good” and “very good” fitness had better measured fitness than those who reported “very poor” and “poor” fitness (all p<0.001). Test–retest reliability of IFIS items was also good, with an average weighted Kappa of 0.811. Therefore, our findings suggest that self-reported fitness, as assessed by IFIS, is a valid, reliable, and health-related measure, and it can be a good alternative for future use in large studies with Latin-schoolchildren from Colombia.