Muscle quality index in obese subjects with hip osteoarthritis

Nueva publicación en la revista Rehumatic Diseases de nuestros compañeros de la Red Ploekinetic, Dr. Jérez (Chile) y Dr. Machado (España).

Abstract

Background Obese older adults with hip osteoarthritis suffer a progressive loss of neuromuscular function affecting their activities of daily living.

Objectives The objective of this study is to determine the behaviour of the muscular quality index in obese subjects with osteoarthritis and to compare the manifestations of strength and anthropometric variables with control subjects.

Methods Thirty-two subjects (4 men and 28 women, 66.2±5.2 years of age, 159.2±7.5 cm, 71.5±11.7 kg) were evaluated. 14 subjects suffered osteoarthritis. Muscle circumference, limb length, body mass and sit and stand test were evaluated, in addition to the maximal voluntary isometric contraction in hip flexion and extension movements.

Results The osteoarthritis group presented obesity (p=0.037). The muscle quality index of the osteoarthritis group correlated with the weight (p=0.776**), with maximum peak strength in flexion (p=0.552*) and average maximal strength (p=0.574*). In the control group the muscle quality index correlated with: weight (p=0.689**), muscle circumference (p=0.571*), maximum peak strength in extension (p=0.534*), average peak strength in extension (p=0,523*), average maximal strength in extension (p=0.509*) and maximum impulse in extension (p=0.508*).

Conclusions The muscle quality index is a useful tool to measure muscle quality in the healthy population, but is not clear enough for obese subjects with osteoarthritis, so it is necessary to perform future studies to determine their behaviour.

http://dx.doi.org/10.1136/annrheumdis-2018-eular.4586

Validity and reliability of evaluating hip abductor strength

Destacada publicación de los miembros de nuestra red en la prestigiosa revista Plos one.

Abstract

The hip abductor muscles are vitally important for pelvis stability, and common strength deficits can negatively affect functionality. The muscle strength can be measured using different dynamometers and be evaluated in three positions (side-lying, standing, and supine). Obtained strength data can be expressed in different ways, with data normalization providing more objective and comparable results. The aim of this study was to establish the validity and reliability of three protocols in evaluating the isometric strength of the hip abductor muscles. A new functional electromechanical dynamometer assessed strength in three positions, with findings subjected to three data normalization methods. In two identical sessions, the hip abductor strengths of 29 subjects were recorded in the side-lying, standing, and supine positions. Peak force was recorded in absolute terms and normalized against body mass, fat-free mass, and an allometric technique. The peak force recorded in the side-lying position was 30% and 27% higher than in the standing and supine positions, respectively, independent of data normalization methodology. High inter-protocol correlations were found (r: 0.72 to 0.98, p ≤ 0.001). The supine position with allometric data normalization had the highest test-retest reliability (0.94 intraclass correlation coefficient and 5.64% coefficient of variation). In contrast, the side-lying position with body mass data normalization had a 0.66 intraclass correlation coefficient and 9.8% coefficient of variation. In conclusion, the functional electromechanical dynamometer is a valid device for measuring isometric strength in the hip abductor muscles. The three assessed positions are reliable, although the supine position with allometric data normalization provided the best results.

Disponible en: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0202248

The relationship between hand prehensile strength, clinical activity and functional capacity in patients with rheumatoid arthritis

Nueva publicación en conjunto de nuestros compañeros de la red, los doctores Iris Paola Guzmán (México) y Daniel Jérez (Chile).

Abstract

Background The hand is an anatomical structure with a large number of joints; its prehensile grasp capability constitutes a highly specialised biomechanical function. In rheumatoid arthritis (RA), the structures of the joint are damaged by the characteristic inflammatory process1 The Disease Activity Score (DAS28) considers twenty hand joints in the evaluation of rheumatoid arthritis (RA). While the Health Assessment Questionnaire (HAQ) disability index (DI) (HAQ-DI) is the most frequently used instrument for measuring self-reported physical function in rheumatoid arthritis and considers the ability to dress and groom, get up, eat, hygiene, reach, grasp, situations in which the functional capability of the hand is crucial.

Objectives To assess the relationship between hand prehensile strength, the DAS28 index and HAQ-DI score in patients with diagnosis of RA.

Methods The prehensile strength was obtained by the dynamometry method from 105 AR patients, the maximum strength levels in the dominant and non-dominant hand were considered. The Disease Activity Score in 28 joints using the erythrocyte sedimentation rate (DAS28-ESR) and HAQ-DI were recorded.

Results The maximum prehensile strength, on average, was 14 kg, and the weak force category was more prevalent. The prehensile strength of both hands was negatively correlated with the HAQ-DI score and DAS28 index. In an adjusted logistic regression model, the ”weak” strength category of the non-dominant hand was associated with “moderate clinical activity” in the DAS28 score (OR=8.59, p=0.02), while the category of ”weak” strength of the dominant hand was associated with the presence of ”some difficulty” of HAQ-DI score (OR=4.75, p=0.10).

Conclusions The decrease in prehensile strength represents a marker associated with the DAS28 index and HAQ-DI score in the patient with RA, regardless of age, muscle mass, total fat or body mass. The measurement of the prehensile strength can be a useful and inexpensive tool to be considered in the clinical evaluation of the RA.

Reference [1] Janet L Poole. Hand Function in Rheumatoid Arthritis. Mehmet Tuncay Duruöz A Practical Guide to Assessment. Springer. 2014. [ISBN:978–1–4614–9448–5]

http://dx.doi.org/10.1136/annrheumdis-2018-eular.7534

¿Qué tanto sabemos sobre evaluación de potencia con saltos verticales? (parte 3)

PhD. Gabriel Fábrica
Universidad de la República (Uruguay)
cgfabrica@gmail.com

¿Qué factores influyen en la diferencia de altura alcanzada en un CMJ respecto a un SJ?

La presencia de esa fase previa de contramovimiento o contrabalanceo hace que en general la altura alcanzada con un CMJ resulte mayor a la alcanzada con un SJ. Muchos estudios han sido realizados con la idea de explicar de qué manera el contrabalanceo permite que al final de la fase de empuje el centro de masa del saltador cuente con mayor velocidad vertical y por tanto el sujeto salte más alto. La primera idea intuitiva sugerida por el profesor Carmelo Bosco fue que la fase excéntrica previa a la concéntrica (de los extensores), permite acumular energía potencial elástica que luego puede ser aprovechada durante la fase concéntrica. De hecho el profesor Bosco llamo a la diferencia porcentual relativa entre las alturas alcanzadas con ambos saltos “índice elástico”. Pero el hecho es que desde los primeros estudios hasta la fecha, no hay ningún resultado que confirme esto. En los escasos trabajos donde se establece una discusión en favor del aprovechamiento elástico como factor determinante de la diferencia de alturas entre un CMJ y un SJ, el efecto es indirecto. Es decir, la importancia de esta acción no es pasiva, sino que el aprovechamiento elástico favorece la acción muscular. De manera que en términos generales podemos decir que la diferencia de altura se debe a una acción activa diferente durante las fases concéntricas de un SJ y un CMJ. Ahora bien, que significa una acción activa diferente. La acción activa implica el análisis del comportamiento de los principales músculos que actúan en el movimiento, esto se puede analizar directamente mediante electromiografía de superficie o indirectamente con modelos que utilizan como entrada datos obtenidos con electromiografía de superficie. Los estudios de electromiografía cuentan con la ventaja de que permiten visualizar la acción muscular, los modelos por su parte hacen posible la predicción de diferentes situaciones sin necesidad de experimentación así como la integración de información. Los resultados de estudios electromiográficos realizados en SJ y CMJ en general conducen a la idea de que el preestiramiento produce un aumento del estado activo de algunos extensores en el inicio de la fase concéntrica. Por su parte, algunos resultados obtenidos con modelos permiten sugerir que la coordinación quizá sea determinante principal de la altura alcanzada y que un CMJ más que un salto potente es un salto eficiente, en el sentido que la potencia generada con los elementos activos es mejor aprovechada que en un SJ.