The synergy of elbow extensor muscles during dynamic work in man

1980 ◽  
Vol 44 (3) ◽  
pp. 271-278 ◽  
Author(s):  
B. Maton ◽  
S. Le Bozec ◽  
J. C. Cnockaert
Keyword(s):  
Dynamic Work ◽  
Extensor Muscles ◽  
Elbow Extensor

Variability of Positioning Accuracy following a Maximum Isometric Contraction

1987 ◽  
Vol 64 (3) ◽  
pp. 759-764 ◽  
Author(s):  
Bruce R. Etnyre ◽  
Eva J. Lee ◽  
Hally B. W. Poindexter
Keyword(s):  
Isometric Contraction ◽  
Constant Error ◽  
Elbow Extension ◽  
Positioning Accuracy ◽  
Extensor Muscles ◽  
Delay Times ◽  
Contraction Times ◽  
The Subject ◽  
Experimental Trials ◽  
Elbow Extensor

The purpose of this study was to examine the effects of different contraction times and delay times prior to a positioning task. While blindfolded, each of 25 subjects learned to produce elbow-extension movements to a short and a long target using a kinesthesiometer. The subject then produced 30 trials without feedback to each target. These control trials were preceded by a foreperiod of 0-, 3-, or 6-sec. delay. The 60 experimental trials were identical to control trials except the subject isometrically contracted elbow extensor muscles for 3 or 6 sec. prior to each trial. Following each isometric contraction the subject delayed movement for 0, 3, or 6 sec. The 3-sec. and 6-sec. prepositioning contractions produced greater undershooting and variability than no prepositioning contractions, and the 0-sec. delay produced less constant error than either the 3- or 6-sec. delay. It was concluded that following isometric contraction, undershooting a target occurred and this effect did not dissipate within a 6-sec. period.

Morpho-functional response of the elbow extensor muscles to twelve-week self-perceived maximal resistance training

2010 ◽  
Vol 30 (6) ◽  
pp. 413-419 ◽  
Author(s):  
Jelena Z. Popadic Gacesa ◽  
Djordje G. Jakovljevic ◽  
Dusko B. Kozic ◽  
Natasa R. Dragnic ◽  
David A. Brodie ◽  
...  
Keyword(s):  
Resistance Training ◽  
Functional Response ◽  
Extensor Muscles ◽  
Elbow Extensor

Reflex and Intrinsic Changes Induced by Fatigue of Human Elbow Extensor Muscles

2001 ◽  
Vol 86 (3) ◽  
pp. 1086-1094 ◽  
Author(s):  
Li-Qun Zhang ◽  
W. Zev Rymer
Keyword(s):  
Small Amplitude ◽  
Joint Stiffness ◽  
Rest Period ◽  
Equation Model ◽  
Joint Torque ◽  
Intracellular Acidosis ◽  
Extensor Muscles ◽  
Reflex Gain ◽  
Intrinsic Stiffness ◽  
Elbow Extensor

Fatigue-induced changes in intrinsic and reflex properties of human elbow extensor muscles and the underlying mechanisms for fatigue compensation were investigated. The elbow joint was perturbed using small-amplitude and pseudorandom movement patterns while subjects maintained steady levels of mean joint extension torque. Intrinsic and reflex properties were identified simultaneously using a nonlinear delay differential equation model. Intrinsic joint properties were characterized by measures of joint stiffness, viscous damping, and limb inertia and reflex properties characterized by measures of dynamic and static reflex gains. Fatigue was induced using 15 min of intermittent voluntary isometric (submaximal) exercise, and a rest period of 10 min was taken to allow the fatigued muscles torecover from acute fatigue effects. Identical experimental and data analysis procedures were used before and after fatigue. Our findings were that after fatigue, joint stiffness was significantly reduced at higher torque levels, presumably reflecting the reduced force-generating capacity of fatigued muscles. Conversely, joint viscosity was increased after fatigue potentially because of the reduced crossbridge detachment rate and prolonged relaxation associated with intracellular acidosis accompanying fatigue. Static stretch reflex gain decreased significantly at higher torque levels after fatigue, indicating that the isometric fatiguing exercise might be associated with a preferential change in properties of spindle chain fibers and bag2 fibers. For matched pre- and postfatigue torque levels, dynamic reflexes contributed relatively more torque after fatigue, displaying higher dynamic reflex gains and larger dynamic electromyographic responses elicited by the controlled small-amplitude position perturbations. These changes appear to counteract the fatigue-induced reductions in joint stiffness and static reflex gain. The compensatory responses could be partly due to the effects of increasing the number of active motoneurons innervating the fatiguing muscles. This shift in operating point gave rise to significant compensation for the loss of contractile force. The compensation could also be due to fusimotor adjustment, which could make the dynamic reflex gain much less sensitive to fatigue than intrinsic stiffness. In short, the reduced contribution from intrinsic stiffness to joint torque was compensated by increased contribution from dynamic stretch reflexes after fatigue.

Central and peripheral fatigue in knee and elbow extensor muscles after a long-distance cross-country ski race

2016 ◽  
Vol 27 (9) ◽  
pp. 945-955 ◽  
Author(s):  
G. Boccia ◽  
D. Dardanello ◽  
C. Zoppirolli ◽  
L. Bortolan ◽  
C. Cescon ◽  
...  
Keyword(s):  
Peripheral Fatigue ◽  
Long Distance ◽  
Extensor Muscles ◽  
Cross Country ◽  
Elbow Extensor

scholarly journals Isokinetic Strength of Elbow Extensor Muscles Correlates with Race Time in Wheelchair Half Marathon Racers

1999 ◽  
Vol 21 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Takamitsu KAWAZU ◽  
Fumihiro TAJIMA ◽  
Kenichiro MAKINO ◽  
Hiroyuki OKAWA ◽  
Yuichi UMEZU ◽  
...  
Keyword(s):  
Isokinetic Strength ◽  
Race Time ◽  
Extensor Muscles ◽  
Elbow Extensor
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