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Muscle Action (muscle + action)

Distribution by Scientific Domains
Life Sciences75%

Terms modified by Muscle Action

  • muscle action potential
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    Selected Abstracts

    Chest wall kinematics, respiratory muscle action and dyspnoea during arm vs. leg exercise in humans

    ACTA PHYSIOLOGICA, Issue 1 2006
    I. Romagnoli
    Abstract Aim:, We hypothesize that different patterns of chest wall (CW) kinematics and respiratory muscle coordination contribute to sensation of dyspnoea during unsupported arm exercise (UAE) and leg exercise (LE). Methods:, In six volunteer healthy subjects, we evaluated the volumes of chest wall (Vcw) and its compartments, the pulmonary apposed rib cage (Vrc,p), the diaphragm-abdomen apposed rib cage (Vrc,a) and the abdomen (Vab), by optoelectronic plethysmography. Oesophageal, gastric and trans-diaphragmatic pressures were simultaneously measured. Chest wall relaxation line allowed the measure of peak rib cage inspiratory muscle, expiratory muscle and abdominal muscle pressures. The loop Vrc,p/Vrc,a allowed the calculation of rib cage distortion. Dyspnoea was assessed by a modified Borg scale. Results:, There were some differences and similarities between UAE and LE. Unlike LE with UAE: (i) Vcw and Vrc,p at end inspiration did not increase, whereas a decrease in Vrc,p contributed to decreasing CW end expiratory volume; (ii) pressure production of inspiratory rib cage muscles did not significantly increase from quiet breathing. Not unlike LE, the diaphragm limited its inspiratory contribution to ventilation with UAE with no consistent difference in rib cage distortion between UAE and LE. Finally, changes in abdominal muscle pressure, and inspiratory rib cage muscle pressure predicted 62% and 41.4% of the variability in Borg score with UAE and LE, respectively (P < 0.01). Conclusion:, Leg exercise and UAE are associated with different patterns of CW kinematics, respiratory muscle coordination, and production of dyspnoea. [source]

    Specificity of muscle action after anterior cruciate ligament injury

    JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2003
    Glenn N. Williams
    Abstract Neuromuscular control is believed to be a critical factor in dynamic knee stability. The purpose of this study was to evaluate voluntary muscle control in anterior cruciate ligament deficient (ACL-D) and uninjured people. Twenty athletes of similar age participated in this study. Subjects performed a target-matching protocol that required them to produce isometric moments about the knee with fine control in flexion, extension, varus, and valgus (i.e., loads were generated in the plane perpendicular to the long axis of the shank). Electromyographic data were collected from 10 muscles that span the knee. A specificity index was calculated for each muscle to describe how fine-tuned (specific) its muscle activity pattern was with respect to its principal direction of action in the load plane. Diminished specificity of muscle action was observed in 8 of 10 muscles in the ACL-D subjects' involved knees when compared with the activity patterns from their uninvolved knees and those from the uninjured subjects' knees. The vastus lateralis muscle was especially affected. Increased and more global co-contraction was also observed in the ACL-D limbs. The alterations in muscle firing patterns observed in this study are consistent with diminished neuromuscular control. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source]

    Linearity and reliability of the mechanomyographic amplitude versus dynamic torque relationships for the superficial quadriceps femoris muscles

    MUSCLE AND NERVE, Issue 3 2010
    Matthew S. Stock MS
    Abstract The purpose of this investigation was to examine the linearity and reliability of the mechanomyographic (MMG) amplitude versus dynamic torque relationships for the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles. Nine healthy men and 11 healthy women performed submaximal to maximal, concentric, isokinetic muscle actions of the leg extensors at 30° s,1 on two occasions. Surface MMG signals were detected from the VL, RF, and VM of the dominant thigh during both trials. The ranges of the coefficients of determination for the MMG amplitude versus dynamic torque relationships were 0.01,0.94 for the VL, 0.01,0.84 for the RF, and 0.19,0.96 for the VM. The intraclass correlation coefficients for the linear MMG amplitude versus torque slope coefficients were 0.823 (VL), 0.792 (RF), and 0.927 (VM). These results indicate that, when analyzed for individual subjects, the MMG amplitude versus dynamic torque relationships demonstrated inconsistent linearity. When using MMG in the clinical setting, dynamic muscle actions of the superficial quadriceps femoris muscles do not appear to be appropriate for assessing changes in muscle function during strength training. Muscle Nerve, 2009 [source]