scholarly journals Muscle length matters: new insights into the neural control of lengthening muscle actions of the knee extensors

2017 ◽  
Vol 102 (11) ◽  
pp. 1393-1394 ◽  
Author(s):  
Martin Behrens
Keyword(s):  
Neural Control ◽  
Muscle Length ◽  
Knee Extensors ◽  
Muscle Actions

P-37 Caffeine increased neural activation and strength of the knee extensors during isometric and dynamic muscle actions

2016 ◽  
Vol 50 (Suppl 1) ◽  
pp. A51-A51
Author(s):  
Martin Behrens ◽  
Matthias Weippert ◽  
Florian Husmann ◽  
Sven Bruhn ◽  
Volker Zschorlich ◽  
...  
Keyword(s):  
Knee Extensors ◽  
Neural Activation ◽  
Muscle Actions

scholarly journals Postural Dependence of Muscle Actions: Implications for Neural Control

1997 ◽  
Vol 17 (6) ◽  
pp. 2128-2142 ◽  
Author(s):  
Christopher A. Buneo ◽  
John F. Soechting ◽  
Martha Flanders
Keyword(s):  
Neural Control ◽  
Muscle Actions

scholarly journals Patterns of intermuscular inhibitory force feedback across cat hindlimbs suggest a flexible system for regulating whole limb mechanics

2018 ◽  
Vol 119 (2) ◽  
pp. 668-678 ◽  
Author(s):  
Mark A. Lyle ◽  
T. Richard Nichols
Keyword(s):  
Neural Control ◽  
Force Feedback ◽  
Control Variable ◽  
Knee Extensors ◽  
Flexor Hallucis Longus ◽  
Directional Bias ◽  
Decerebrate Cat ◽  
Golgi Tendon Organs ◽  
Extensor Muscles ◽  
Inhibitory Feedback

Prior work has suggested that Golgi tendon organ feedback, via its distributed network linking muscles spanning all joints, could be used by the nervous system to help regulate whole limb mechanics if appropriately organized. We tested this hypothesis by characterizing the patterns of intermuscular force-dependent feedback between the primary extensor muscles spanning the knee, ankle, and toes in decerebrate cat hindlimbs. Intermuscular force feedback was evaluated by stretching tendons of selected muscles in isolation and in pairwise combinations and then measuring the resulting force-dependent intermuscular interactions. The relative inhibitory feedback between extensor muscles was examined, as well as symmetry of the interactions across limbs. Differences in the directional biases of inhibitory feedback were observed across cats, with three patterns identified as points on a spectrum: pattern 1, directional bias of inhibitory feedback onto the ankle extensors and toe flexors; pattern 2, convergence of inhibitory feedback onto ankle extensors and mostly balanced inhibitory feedback between vastus muscle group and flexor hallucis longus, and pattern 3, directional bias of inhibitory feedback onto ankle and knee extensors. The patterns of inhibitory feedback, while different across cats, were symmetric across limbs of individual cats. The variable but structured distribution of force feedback across cat hindlimbs provides preliminary evidence that inhibitory force feedback could be a regulated neural control variable. We propose the directional biases of inhibitory feedback observed experimentally could provide important task-dependent benefits, such as directionally appropriate joint compliance, joint coupling, and compensation for nonuniform inertia. NEW & NOTEWORTHY Feedback from Golgi tendon organs project widely among extensor motor nuclei in the spinal cord. The distributed nature of force feedback suggests these pathways contribute to the global regulation of limb mechanics. Analysis of this network in individual animals indicates that the strengths of these pathways can be reorganized appropriately for a variety of motor tasks, including level walking, slope walking, and landing.

Differential costal and crural diaphragm compensation for posture changes

1985 ◽  
Vol 58 (6) ◽  
pp. 1895-1900 ◽  
Author(s):  
E. van Lunteren ◽  
M. A. Haxhiu ◽  
N. S. Cherniack ◽  
M. D. Goldman
Keyword(s):  
Neural Control ◽  
Muscle Length ◽  
Control Mechanisms ◽  
Fine Wire ◽  
Supine Posture ◽  
Crural Diaphragm ◽  
Resting Muscle

The electromyographic (EMG) activities of the costal and crural diaphragm were recorded from bipolar fine-wire electrodes placed in the costal fibers adjacent to the central tendon and in the anterior portions of the crural fibers in 12 anesthetized cats. The EMG activities of costal and crural recordings were compared during posture changes from supine to head up and during progressive hyperoxic hypercapnia in both positions. The activity of both portions of the diaphragm was greater in the head up compared with supine posture at all levels of CO2; and increases in crural activity were greater than those in costal activity both as a result of changes in posture and with increasing CO2 stimuli. These results are consistent with the concept that diaphragm activation is modulated in response to changes in resting muscle length, and further, that neural control mechanisms allow separate regulation of costal and crural diaphragm activation.

Muscle activation and blood flow do not explain the muscle length-dependent variation in quadriceps isometric endurance

2005 ◽  
Vol 98 (3) ◽  
pp. 810-816 ◽  
Author(s):  
R. D. Kooistra ◽  
C. J. de Ruiter ◽  
A. de Haan
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Vastus Lateralis ◽  
Muscle Length ◽  
Rectus Femoris ◽  
Surface Emg ◽  
Knee Extensors ◽  
Emg Activity ◽  
Central Activation ◽  
Full Occlusion

We investigated the role of central activation in muscle length-dependent endurance. Central activation ratio (CAR) and rectified surface electromyogram (EMG) were studied during fatigue of isometric contractions of the knee extensors at 30 and 90° knee angles (full extension = 0°). Subjects ( n = 8) were tested on a custom-built ergometer. Maximal voluntary isometric knee extension with supramaximal superimposed burst stimulation (three 100-μs pulses; 300 Hz) was performed to assess CAR and maximal torque capacity (MTC). Surface EMG signals were obtained from vastus lateralis and rectus femoris muscles. At each angle, intermittent (15 s on 6 s off) isometric exercise at 50% MTC with superimposed stimulation was performed to exhaustion. During the fatigue task, a sphygmomanometer cuff around the upper thigh ensured full occlusion (400 mmHg) of the blood supply to the knee extensors. At least 2 days separated fatigue tests. MTC was not different between knee angles (30°: 229.6 ± 39.3 N·m vs. 90°: 215.7 ± 13.2 N·m). Endurance times, however, were significantly longer ( P < 0.05) at 30 vs. 90° (87.8 ± 18.7 vs. 54.9 ± 12.1 s, respectively) despite the CAR not differing between angles at torque failure (30°: 0.95 ± 0.05 vs. 90°: 0.96 ± 0.03) and full occlusion of blood supply to the knee extensors. Furthermore, rectified surface EMG values of the vastus lateralis (normalized to prefatigue maximum) were also similar at torque failure (30°: 56.5 ± 12.5% vs. 90°: 58.3 ± 15.2%), whereas rectus femoris EMG activity was lower at 30° (44.3 ± 12.4%) vs. 90° (69.5 ± 25.3%). We conclude that differences in endurance at different knee angles do not find their origin in differences in central activation and blood flow but may be a consequence of muscle length-related differences in metabolic cost.

scholarly journals Muscle length effect on corticospinal excitability during maximal concentric, isometric and eccentric contractions of the knee extensors

2017 ◽  
Vol 102 (11) ◽  
pp. 1513-1523 ◽  
Author(s):  
Valentin Doguet ◽  
Kazunori Nosaka ◽  
Arnaud Guével ◽  
Gary Thickbroom ◽  
Kazuhiro Ishimura ◽  
...  
Keyword(s):  
Muscle Length ◽  
Corticospinal Excitability ◽  
Eccentric Contractions ◽  
Knee Extensors ◽  
Length Effect
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