The relationship of testosterone and AR CAG repeat genotype with knee extensor muscle function of young and older men

2012 ◽  
Vol 47 (6) ◽  
pp. 437-443 ◽  
Author(s):  
J.P. Folland ◽  
T.M. Mc Cauley ◽  
C. Phypers ◽  
B. Hanson ◽  
S.S. Mastana
Keyword(s):  
Muscle Function ◽  
Knee Extensor ◽  
Older Men ◽  
Extensor Muscle ◽  
Cag Repeat ◽  
Relationship Of ◽  
The Relationship

Effect of voluntary vs. artificial activation on the relationship of muscle torque to speed

1990 ◽  
Vol 69 (6) ◽  
pp. 2215-2221 ◽  
Author(s):  
G. A. Dudley ◽  
R. T. Harris ◽  
M. R. Duvoisin ◽  
B. M. Hather ◽  
P. Buchanan
Keyword(s):  
Knee Extensor ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Angular Velocities ◽  
The Central Nervous System ◽  
The Right ◽  
Artificial Activation ◽  
Relationship Of ◽  
The Relationship ◽  
Eccentric Actions

The speed-torque relationship of the right knee extensor muscle group was investigated in eight untrained subjects (28 +/- 2 yr old). Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at nine angular velocities (0.17-3.66 rad/s) and during isometric actions. Activation was by "maximal" voluntary effort or by transcutaneous tetanic electrical stimulation that induced an isometric torque equal to 60% (STIM 1) or 45% (STIM 2) of the voluntary isometric value. Torque increased (P less than 0.05) to 1.4 times isometric as the speed of eccentric actions increased to 1.57 rad/s for STIM 1 and STIM 2. Thereafter, increases in eccentric speed did not further increase torque. Torque did not increase (P greater than 0.05) above isometric for voluntary eccentric actions. As the speed of concentric actions increased from 0.00 to 3.66 rad/s, torque decreased (P less than 0.05) more (P less than 0.05) for both STIM 1 and STIM 2 (two-thirds) than for voluntary activation (one-half). As a result of these responses, torque changed three times as much (P less than 0.05) across speeds of concentric and eccentric actions with artificial (3.4-fold) than voluntary (1.1-fold) activation. The results indicate that with artificial activation the normalized speed-torque relationship of the knee extensors in situ is remarkably similar to that of isolated muscle. The relationship for voluntary activation, in contrast, suggests that the ability of the central nervous system to activate the knee extensors during maximal efforts depends on the speed and type of muscle action performed.

scholarly journals A CROSS-SECTIONAL STUDY—THE RELATIONSHIP OF MUSCLE MASS AND MUSCLE FUNCTION WITH AGE

2017 ◽  
Vol 1 (suppl_1) ◽  
pp. 589-589
Author(s):  
J. Sun ◽  
H. Bai ◽  
M. Chen ◽  
D. Xue ◽  
J. Chen
Keyword(s):  
Muscle Mass ◽  
Muscle Function ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Relationship Of ◽  
The Relationship

Relationship of The Knee Extensor Strength But Not The Quadriceps Femoris Muscularity With Sprint Performance in Sprinters: A Reexamination and Extension

2021 ◽  
Author(s):  
Miyuki Hori ◽  
Tadashi Suga ◽  
Masafumi Terada ◽  
Takahiro Tanaka ◽  
Yuki Kusagawa ◽  
...  
Keyword(s):  
Knee Extensor ◽  
Knee Extension ◽  
Quadriceps Femoris ◽  
Sprint Performance ◽  
Sprint Time ◽  
Knee Extensor Strength ◽  
Significant Difference ◽  
The Absolute ◽  
Relationship Of ◽  
The Relationship

Abstract Purpose: This study examined the relationships of the knee extensor strength and quadriceps femoris size with sprint performance in sprinters. Methods: Fifty-eight male sprinters and 40 body size-matched male non-sprinters participated in this study. The knee extensor isometric and isokinetic strengths were measured using a dynamometer. The isokinetic strength measurements were performed with slow and fast velocities at 60°/s and 180°/s, respectively. The quadriceps femoris muscle volume (MV) was measured using magnetic resonance imaging. The relative values of the knee extensor strengths and quadriceps femoris MV were normalized to body mass.Results: The absolute and relative values of the two velocity isokinetic strengths, but not of isometric strength, of the knee extension were significantly higher in sprinters than in non-sprinters (both Ps < 0.05). Such a significant difference was also observed for the relative quadriceps femoris MV (P = 0.018). In sprinters, there were significant correlations between all three knee extensor strengths and quadriceps femoris MV (r = 0.421 to 0.531, all Ps £ 0.001). The absolute and relative strengths of the fast-velocity isokinetic knee extension correlated with personal best 100-m sprint time (r = -0.477 and -0.409, respectively, both Ps £ 0.001). By contrast, no significant correlations were observed between absolute and relative quadriceps femoris MVs and personal best 100-m sprint time. Conclusions: These findings suggest that despite the presence of the relationship between muscle strength and size, the knee extensor strength may be related to superior sprint performance in sprinters independently of the quadriceps femoris muscularity.

scholarly journals Absence of a linear relationship between the reflex flexor shortenings evoked by a graded series of flexion-producing stimuli and the “inhibitory" lengthenings of a constant extension reflex evoked by the same stimuli

1927 ◽  
Vol 102 (715) ◽  
pp. 150-158
Keyword(s):  
Linear Relationship ◽  
Extensor Muscle ◽  
Reflex Effect ◽  
Relationship Of ◽  
The Relationship ◽  
Antagonistic Muscles ◽  
Flexion And Extension

When each of a graded series of flexion-producing stimuli is compounded with a constant extension-producing stimulus, a common reflex effect is that both of two antagonistic muscles—a flexor and an extensor—exhibit a smaller magnitude of shortening in the compound reflex than in their respective simple reflexes. Such a series of compound reflexes affords the opportunity of analys­ing various possible relationships. One relationship—that between the “simple” and the “compound” flexor shortening—was examined in a pre­ceding paper. The reverse aspect of this particular relationship is obtained by contrasting each different magnitude of “simple” flexor shortening with the corresponding magnitude of concurrent lengthening (“relaxation”) in the extensor muscle. The present paper is devoted to an examination of this particular relationship. The relationship of flexor shortening and concurrent extensor lengthening is that which has chiefly been used by Sherrington for the establishment of the principle of the “reciprocal innervation of antagonistic muscles.” Not­ withstanding the interest and importance of this relationship, the reflex magni­tudes involved have not hitherto been examined. All examinations have been more or less qualitative, and any theoretical illustrations—by the giving of hypothetical numerical values to flexion and extension (including, in each case, “excitation” and “inhibition”)—have been made on the assumption of equality between “excitation” and “inhibition.” The writer has, however, shown that one particular reflex phenomenon—the concurrence in compound reflexes of a remainder of shortening in both of the antagonistic muscles—is inexplicable on the assumption that there is equality between “excitation” and “inhibition.”

scholarly journals The Relationship of Knee-Extensor Strength and Rate of Torque Development to Sit-to-Stand Performance in Older Adults

2013 ◽  
Vol 65 (3) ◽  
pp. 229-235 ◽  
Author(s):  
Katie Crockett ◽  
Kimberly Ardell ◽  
Marlyn Hermanson ◽  
Andrea Penner ◽  
Joel Lanovaz ◽  
...  
Keyword(s):  
Older Adults ◽  
Knee Extensor ◽  
Sit To Stand ◽  
Rate Of Torque Development ◽  
Knee Extensor Strength ◽  
Relationship Of ◽  
The Relationship ◽  
Torque Development
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