Josária Ferraz Amaral

Comparison of three hand dynamometers in relation to the accuracy and precision of the measurements

CONTEXTUALIZACAO: Dada a variedade de dinamometros disponiveis para mensurar a forca de preensao manual com diferentes formatos de empunhaduras, estudos de confiabilidade fazem-se necessarios. Objetivos: Comparar a exatidao e a precisao das medidas de tres dinamometros distintos e analisar a influencia do perfil de empunhadura de cada um. METODOS: Os testes foram realizados com os dinamometros Jamar®, Takei® e o Transdutor Manual EMG System com empunhadura modificada. Foram avaliados 18 voluntarios saudaveis, com idade de 20±1,3 anos, sem historico de doenca musculoesqueletica ou traumas nos membros avaliados. A normalidade dos dados foi testada por meio do teste Shapiro-Wilk. Para verificar as possiveis diferencas entre as medicoes dos dinamometros, aplicou-se uma ANOVA para medidas repetidas seguida do post-hoc de Tukey. A confiabilidade entre as medidas foi avaliada por meio do Coeficiente de Correlacao Intraclasse (CCI), e a concordância foi testada utilizando o procedimento de Bland e Altman. Para o procedimento de calibracao dos dinamometros, procedeu-se a analise de regressao linear e de covariância. RESULTADOS: Observou-se diferenca estatisticamente significativa entre o dinamometro Jamar® e os dinamometros Takei® (feminino p<0,001 e masculino p=0,022) e Transdutor (feminino p<0,001 e masculino p=0,007). Todavia, Takei® e Transdutor mostraram-se semelhantes para o grupo feminino (p=0,161) e masculino (p=0,850). Apesar de valores aceitaveis de correlacao intraclasse entre as medidas, pode-se observar baixa concordância entre o dinamometro Jamar® e dos demais instrumentos. CONCLUSOES: Constatou-se a influencia dos formatos das empunhaduras na medicao da forca muscular de preensao da mao como tambem a necessidade de calibracao previa desse tipo de instrumento.BACKGROUND Given the variety of available hand-held dynamometers and their different handle shapes, reliability studies are needed. OBJECTIVES To compare the accuracy and reliability between three different hand-held dynamometers and analyze the influence of their handles on grip strength. METHODS The tests were performed with the Jamar® dynamometer, the Takei® dynamometer and the EMG System Manual Transducer with modified handle. Eighteen healthy volunteers aged 20.0±1.3 years without history of musculoskeletal disorders or trauma in the evaluated limbs were included. Data normality was tested using the Shapiro-Wilk test. To verify possible differences between the dynamometers, repeated measures ANOVA was administered, followed by Tukey post-hoc tests. Reliability between measurements was evaluated using intraclass correlation coefficient (ICC) and agreement was tested using Bland and Altman plots. The dynamometers calibration process was evaluated using linear regressions. RESULTS We observed statistically significant differences on the female group between the Jamar® and the Takei® dynamometers (females p<0.001 and males p=0.022) and the EMG System Manual Transducer (female p<0.001 and males p=0.007). However, the Takei® dymamometer and the EMG System Manual Transducer were similar for both female (p=0.161) and male groups (p=0.850). Although acceptable values of intraclass correlation coefficients between measurements were identified, low agreement between the Jamar® dynamometer and all other instruments was found. CONCLUSIONS The results demonstrated that there is an influence of the dynamometers handle shapes on the measurements of grip strength. Furthermore, the results demonstrated the need for previous calibration of this type of instrument.

Influence of aging on isometric muscle strength, fat-free mass and electromyographic signal power of the upper and lower limbs in women

Background Aging is a multifactorial process that leads to changes in the quantity and quality of skeletal muscle and contributes to decreased levels of muscle strength. Objective This study sought to investigate whether the isometric muscle strength, fat-free mass (FFM) and power of the electromyographic (EMG) signal of the upper and lower limbs of women are similarly affected by aging. Method The sample consisted of 63 women, who were subdivided into three groups (young (YO) n=33, 24.7±3.5 years; middle age (MA) n=15, 58.6±4.2 years; and older adults (OA). n=15, 72.0±4.2 years). Isometric strength was recorded simultaneously with the capture of the electrical activity of the flexor muscles of the fingers and the vastus lateralis during handgrip and knee extension tests, respectively. FFM was assessed using dual-energy X-ray absorptiometry. Results The handgrip strength measurements were similar among groups (p=0.523), whereas the FFM of the upper limbs was lower in group OA compared to group YO (p=0.108). The RMSn values of the hand flexors were similar among groups (p=0.754). However, the strength of the knee extensors, the FFM of the lower limbs and the RMSn values of the vastus lateralis were lower in groups MA (p=0.014, p=0.006 and p=0.013, respectively) and OA (p=0.000, p=0.000 and p<0.000, respectively) compared to group YO. Conclusions The results of this study demonstrate that changes in isometric muscle strength in MLG and electromyographic activity of the lower limbs are more pronounced with the aging process of the upper limb.

Mudanças no desenvolvimento temporal da força em mulheres de diferentes faixas etárias

INTRODUCCION: reduccion en la fuerza y en la velocidad de la contraccion muscular son dos de las mayores causas de debilidad funcional en ancianos.OBJETIVO: analizar los cambios relacionados a la edad en el desarrollo temporal de la fuerza de aprehension manual y de los extensores de la rodilla en mujeres.METODOS: la muestra fue constituida por 52 mujeres subdivididas en tres grupos (JO. n=24, 25,2±3,7 anos; MI. n=13, 58±4,2 anos; ID. n=15, 71,3±3,9 anos). Los tests realizados fueron el de aprehension manual y el de extension de la rodilla. Fueron ejecutadas tres tentativas de esfuerzo isometrico maximo en cada test, y la curva con el valor maximo de fuerza fue seleccionada para analisis por medio de un algoritmo desarrollado en lenguaje Matlab(r). La masa libre de grasa (MLG) fue evaluada por medio de la absortometria radiologica de doble energia.RESULTADOS: fueron observados entre los grupos valores semejantes de fuerza (p=0,831) y MLG del miembro superior (p=0,207). La tasa de desarrollo de la fuerza (TDF) fue menor en los intervalos iniciales de la contraccion muscular (0-50 y 0-100ms) en los grupos MI (p=0,005 y p=0,000, para 50ms y 100ms, respectivamente) e ID (p=0,003 y p=0,000, para 50ms y 100ms, respectivamente). La MLG y fuerza del miembro inferior fue menor en los grupos MI (p=0,006, p=0,014, respectivamente) e ID (p 0,05), aunque menor en el grupo ID (p<0,05) en comparacion al JO, en todos los intervalos analizados.CONCLUSION: los resultados de este estudio sugieren que los grupos musculares de los miembros superiores e inferiores puedan ser afectados en diferentes magnitudes por el envejecimiento. Las diferencias entre los miembros pueden estar relacionadas a la cantidad y calidad de las actividades fisicas realizadas.

Autonomic and Vascular Control in Prehypertensive Subjects with a Family History of Arterial Hypertension

Background Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology. Objective To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH. Methods Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®). The transfer function analysis was used to measure the gain and response time of baroreflex. The statistical significance adopted was p ≤ 0.05. Results Pre-hypertensive individuals, in relation to normotensive individuals, have higher VC both at rest (3.48 ± 1.26 vs. 2.67 ± 0.72 units, p = 0.05) and peak reactive hyperemia (25, 02 ± 8.18 vs. 18.66 ± 6.07 units, p = 0.04). The indices of cardiac autonomic modulation were similar between the groups. However, in the peripheral autonomic modulation, greater variability was observed in prehypertensive patients compared to normotensive individuals (9.4 [4.9-12.7] vs. 18.3 [14.8-26.7] mmHg2; p < 0.01) and higher spectral components of very low (6.9 [2.0-11.1] vs. 13.5 [10.7-22.4] mmHg2, p = 0.01) and low frequencies (1.7 [1.0-3.0] vs. 3.0 [2.0-4.0] mmHg2, p = 0.04) of SBP. Additionally, we observed a lower gain of baroreflex control in prehypertensive patients compared to normotensive patients (12.16 ± 4.18 vs. 18.23 ± 7.11 ms/mmHg, p = 0.03), but similar delay time (-1.55 ± 0.66 vs. -1.58 ± 0.72 s, p = 0.90). Conclusion Prehypertensive patients with FHSAH have autonomic dysfunction and increased vascular conductance when compared to normotensive patients with the same risk factor.

Peripheral Vascular Resistance Impairment during Isometric Physical Exercise in Normotensive Offspring of Hypertensive Parents

Background A family history of hypertension is associated with vascular and autonomic abnormalities, as well as an impaired neurohemodynamic response to exercise. Objective To test the hypothesis that normotensive individuals with a family history of hypertension present an impaired peripheral vascular resistance response to exercise. Methods The study included 37 normotensive volunteers of both sexes who were sedentary, eutrophic, and nonsmokers, comprising 23 with (FH+; 24 ± 3 years) and 14 without (FH-; 27 ± 5 years) a family history of hypertension. Blood pressure, heart rate (DIXTAL®), forearm blood flow (Hokanson®), and peripheral vascular resistance were simultaneously measured for 3 minutes during rest and, subsequently, for 3 minutes during an isometric exercise at 30% of maximal voluntary contraction (Jamar®). Results At rest, the FH+ and FH- groups present similar mean blood pressure (83 ± 7 versus 83 ± 5 mmHg, p = 0.96), heart rate (69 ± 8 bpm versus 66 ± 7 bpm, p = 0.18), forearm blood flow (3 ± 1 mL/min/100 mL versus 2.7 ± 1 mL/min/100 mL, p = 0.16), and peripheral vascular resistance (30 ± 9 units versus 34±9 units, p = 0.21), respectively. Both groups showed a significant and similar increase in mean blood pressure (∆ = 15 ± 7 mmHg versus 14 ± 7 mmHg, p = 0.86), heart rate (∆ = 12 ± 8 bpm versus 13 ± 7 bpm, p = 0.86), and forearm blood flow (∆ = 0.8 ± 1.2 mL/min/100 mL versus 1.4 ± 1.1 mL/min/100 mL, p = 0.25), respectively, during exercise. However, individuals in the FH+ group showed no reduction in peripheral vascular resistance during exercise, which was observed in the FH- group (∆ = -0.4 ± 8.6 units versus -7.2 ± 6.3 units, p = 0.03). Conclusion Normotensive individuals with a family history of hypertension present an impaired peripheral vascular resistance response to exercise.