Application Progress of Isokinetic Muscle Strength Test in Trunk Core Muscles (review) / 中国康复理论与实践

Isokinetic muscle strength test has been applied to athletes, healthy people and patients with muscular dystrophy, and some results have been achieved. However, due to the different parts, purposes, intensity and methods of training, the information integration are unclear, lacking a complete overview of clinical application of isokinetic muscle test and training. This paper mainly reviewed the current research status of isokinetic muscle strength test and training in various fields of trunk muscle group, including low back pain, stroke, and sports medicine, etc. In addition, the indexes and influencing factors of trunk muscle group and core muscle group were briefly constructed, and some common research methods were integrated.

Muscular performance characterization in athletes: a new perspective on isokinetic variables

Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments. .

Taxa de desenvolvimento de força em diferentes velocidades de contrações musculares / Rate of force development in different muscle contraction velocities

O objetivo deste estudo foi comparar a taxa de desenvolvimento de força (TDF) nas contrações isométrica e isocinética concêntrica a 60º.s-1 e 180º.s-1. Quatorze indivíduos do gênero masculino (idade = 23,1 ± 2,8 anos; estatura = 174 ± 31,3cm; massa corporal = 81 ± 12kg) realizaram inicialmente uma familiarização ao equipamento isocinético. Posteriormente, os indivíduos realizaram em ordem randômica cinco contrações isocinéticas máximas para os extensores do joelho a 60º.s-1 e 180º.s-1 para determinar o torque máximo concêntrico (TMC) e duas contrações isométricas máximas de 3s para determinar o torque máximo isométrico (TMI). O TMI (301,4 ± 56,0N.m) foi maior do que o TMC a 60º.s-1 (239,8 ± 42,2N.m) e 180º.s-1 (175,0 ± 32,5 N.m). O TMC a 60º.s-1 foi maior do que o TMC a 180º.s-1. Para os intervalos de 0-30ms e 0-50ms, a TDF na condição isométrica (1.196,6 ± 464,6 e 1.326,5 ± 514,2N.m.s-1, respectivamente) foi similar à TDF a 60º.s-1 (1.035,4 ± 446,2 e 1.134,3 ± 448,4N.m.s-1) e maior do que a 180º.s-1 (656,7 ± 246,6 e 475,2 ± 197,9N.m.s-1), sendo ainda que a TDF na contração concêntrica a 180º.s-1 foi menor do que a 60º.s-1. No intervalo de 0-100ms, a TDF da contração isométrica (1.248,8 ± 417,4N.m.s-1) foi maior que a obtida na contração isocinética rápida (909,2 ± 283,4N.m.s-1). A TDF obtida na contração isocinética lenta (1.005,4 ± 247,7N.m.s-1) foi similar à obtida na contração isométrica e na concêntrica isocinética rápida. No intervalo 0-150ms, a TDF isométrica (1.084,2 ± 332,1N.m.s-1) foi maior do que as concêntricas (60º.s-1 e 180º.s-1) (834,8 ± 184,2 e 767,6 ± 201,8N.m.s-1, respectivamente), não existindo diferenças entre estas duas últimas. Conclui-se que a TDF é dependente do tipo e da velocidade de contração, suportando a hipótese de que maiores velocidades de contração acarretam maior inibição do drive neural no início do movimento.

The objective of this study was to compare the maximal rate of force development (RFD) at maximal isometric and isokinetic concentric contractions at 60º.s-1 and 180º.s-1. Fourteen active males (age = 23.1 ± 2.8 years; height = 174 ± 31.3 cm and body mass = 81 ± 12 kg) volunteered to participate in this study. During the first visit, subjects performed a familiarization to the isokinetic equipment. During the second visit, subjects performed in random order 5 maximal isokinetic concentric contractions for knee extensors at each angular velocity (60 and 180º.s-1) to determine maximal concentric torque (MCT) and 2 maximal isometric contractions of 3 s to determine maximal isometric torque (MIT). The MIT (301.4 ± 56.0 N.m) was higher than MCT at 60º.s-1 (239.8 ± 42.2 N.m) and 180º.s-1 (175.0 ± 32.5 N.m). The MCT at 60º.s-1 was higher than MCT at 180º.s-1. At intervals of 0-30ms and 0-50ms, the RFD at isometric contraction (1196.6 ± 464.6 and 1326.5 ± 514.2 N.m.s-1, respectively) was similar to that obtained during concentric contraction at 60º.s-1 (1035.4 ± 446.2 N.m.s-1 and 1134.3 ± 448.4 N.m.s-1, respectively) and higher than that obtained during concentric contraction at 180º.s-1 (656.7 ± 246.6 N.m.s-1 and 475,2±197,9 N.m.s-1, respectively). For the interval of 0-100ms, RFD at isometric contraction (1248.7 ± 417.4 N.m.s-1) was higher than that obtained during concentric contractions at 180º.s-1 (909.2 ± 283.4 N.m.s-1), and similar to concentric contractions at 60º.s-1 (1005.4 ± 247.7 N.m.s-1). However, for the interval of 0-150ms, RFD at isometric contraction (1084.2 ± 332.1 N.m.s-1) was higher than at 60º.s-1 (834.8 ± 184.2 N.m.s-1) and 180º.s-1 (767.6 ± 767.6 N.m.s-1). It can be concluded that RFD is dependant on the contraction type and velocity, supporting the hypothesis that higher speed of contraction generates higher neural drive inhibition at the beginning of the movement.

Eccentric strength and endurance in patients with unilateral intermittent claudication

OBJECTIVE: To analyze concentric and eccentric strength and endurance in patients with unilateral intermittent claudication. INTRODUCTION: Basic motor tasks are composed of concentric, isometric, and eccentric actions, which are related and contribute to physical performance. In previous studies of patients with intermittent claudication, the disease-related reduction in concentric and isometric muscular strength and endurance resulted in poorer walking performance. To date, no study has evaluated eccentric muscle action in patients with intermittent claudication. METHODS: Eleven patients with unilateral intermittent claudication performed isokinetic concentric and eccentric actions at the ankle joints to assess peak torque and total work in both symptomatic and asymptomatic legs. RESULTS: Concentric peak torque and total work were lower in the symptomatic than in the asymptomatic leg (80 ± 32 vs. 95 ± 41 N/m, P = 0.01; 1479 ± 667 vs. 1709 ± 879 J, P = 0.03, respectively). There were no differences in eccentric peak torque and total work between symptomatic and asymptomatic legs (96 ± 30 vs. 108 ± 48 N/m; 1852 ± 879 vs. 1891 ± 755 J, respectively). CONCLUSION: Strength and endurance in the symptomatic leg were lower during concentric compared to eccentric action. Future studies are recommended to investigate the mechanisms underlying these responses and to analyze the effects of interventions to improve concentric strength and endurance on functional limitations in patients with intermittent claudication.

Comparison between Isokinetic Method and Electromyographic Method in Muscle Power Measurement of Lumbar Muscles

OBJECTIVE: The purpose of this study was to analyze the relationship between isokinetic measurement and electromyographic method in muscle power measurement of lumbar muscles. METHOD: The subjects were 23 chronic lower back pain patients and 17 normal adult. Isokinetic lumbar extensor strength test was performed at specific speeds (120degrees/sec, 180degrees/sec) with Cybex 770 and automatic turn/amplitude analysis of electromyogram (EMG) was performed with Viking EMG system. RESULTS: The relationship between the parameters of isokinetic test and turn/sec of EMG study was not significantly correlated. The relationship between the parameters of isokinetic test and amplitude of EMG study was significantly correlated. The relationship between the parameters of isokinetic test and ratio of turns to mean amplitude of EMG was not correlated significantly. The mean amplitude in 120degrees/sec speed test and the ratio of turns to mean amplitude in 120degrees/sec and 180degrees/sec speed test were significantly lower in chronic lower back pain patients than that of normal controls. CONCLUSION: Turn/amplitude analysis of EMG method if performed with isometric or isokinetic muscle test will be clinically useful in muscle power measurement of lumbar muscles.

ISOKINETIC STRENGTH AND ENDURANCE OF QUADRICEPS AND HAMSTRING MUSCLES IN ELITE CHINESE ATHLETES / 中国运动医学杂志

The strength and endurance of quadriceps and hamstring muscles have been considered important in sports injury prevention and causation. The purpose of this study was to determine the isokinetic strength and endurance of those muscles of 54 elite male athletes (mean age 21.6 years) and 35 healthy males served as a control group (mean age 20.1 years) using a Cybex Ⅱ~+ system. Three testing speeds (60?/sec, 180?/sec and 240?/sec) were selected.The results indicated that the strength values of the quadriceps and hamstring muscles were significantlly higher in athletes than that in the control group (P