In vivo vastus lateralis force–velocity relationship at the fascicle and muscle tendon unit level

2014 ◽  
Vol 24 (6) ◽  
pp. 934-940 ◽  
Author(s):  
Heiliane de Brito Fontana ◽  
Helio Roesler ◽  
Walter Herzog
Keyword(s):  
Vastus Lateralis ◽  
Unit Level ◽  
Velocity Relationship ◽  
Force Velocity

Training-induced alterations of the in vivo force-velocity relationship of human muscle

1981 ◽  
Vol 51 (3) ◽  
pp. 750-754 ◽  
Author(s):  
V. J. Caiozzo ◽  
J. J. Perrine ◽  
V. R. Edgerton
Keyword(s):  
Training Group ◽  
Knee Extension ◽  
Knee Extensors ◽  
Velocity Relationship ◽  
Slow Velocity ◽  
Group A ◽  
Force Velocity ◽  
Group B ◽  
Relationship Of

Seventeen male and female subjects (ages 20–38 yr) were tested pre- and posttraining for maximal knee extension torque at seven specific velocities (0, 0.84, 1.68, 2.51, 3.35, 4.19, and 5.03 rad . s-1) with an isokinetic dynamometer. Maximal knee extension torques were recorded at a specific joint angle (0.52 rad below the horizontal plane) for all test speeds. Subjects were randomly assigned to one of three experimental groups: group A, control, n = 7; group B, training at 1.68 rad . s-1, n = 5; or group C, training at 4.19 rad . s-1, n = 5. Subjects trained the knee extensors by performing two sets of 10 single maximal voluntary efforts three times a week for 4 wk. Before training, each training group exhibited a leveling-off of muscular tension in the slow velocity-high force region of the in vivo force-velocity relationship. Training at 1.68 rad . s-1 resulted in significant (P less than 0.05) improvements at all velocities except for 5.03 rad . s-1 and markedly affected the leveling-off in the slow velocity-high force region. Training at 4.19 rad . s-1 did not affect the leveling-off phenomenon but brought about significant improvements (P less than 0.05) at velocities of 2.51, 3.35, and 4.19 rad . s-1. The changes seen in the leveling-off phenomenon suggest that training at 1.68 rad . s-1 might have brought about an enhancement of motoneuron activation.

THE USE OF PRECONTRACTIONS TO ENHANCE THE IN VIVO FORCE-VELOCITY RELATIONSHIP

1982 ◽  
Vol 14 (2) ◽  
pp. 162 ◽  
Author(s):  
V. J. Caiozzo ◽  
T. Laird ◽  
K. Chow ◽  
C. A. Prietto ◽  
W. C. McMaster
Keyword(s):  
Velocity Relationship ◽  
Force Velocity

Dynamic Optimization of Maximum-Effort Human Sprinting

2009 ◽  
Author(s):  
Ross H. Miller ◽  
Brian R. Umberger ◽  
Joseph Hamill ◽  
Graham E. Caldwell
Keyword(s):  
Skeletal Muscle ◽  
Dynamic Optimization ◽  
Human Muscle ◽  
Maximum Speed ◽  
Muscle Dynamics ◽  
Velocity Relationship ◽  
Maximum Effort ◽  
Force Velocity ◽  
Relationship Of

Maximum speed is an important parameter for sprinting humans, particularly in athletic competitions. While the biomechanics of sprinting have been well-studied [1–3], our understanding of biomechanical limits to maximum speed is still in its infancy. Previous studies have suggested a speed-limiting role for the force-velocity relationship of skeletal muscle [2], but these theories are difficult to verify experimentally due to the difficulty in observing and manipulating human muscle dynamics in vivo.

scholarly journals Operating length and velocity of human M. vastus lateralis fascicles during vertical jumping

2017 ◽  
Vol 4 (5) ◽  
pp. 170185 ◽  
Author(s):  
Maria Elissavet Nikolaidou ◽  
Robert Marzilger ◽  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Adamantios Arampatzis
Keyword(s):  
Velocity Potential ◽  
Vastus Lateralis ◽  
Power Production ◽  
Velocity Curve ◽  
Mechanical Power ◽  
Jump Height ◽  
Velocity Relationship ◽  
Force Velocity ◽  
The Mean ◽  
Force Potential

Humans achieve greater jump height during a counter-movement jump (CMJ) than in a squat jump (SJ). However, the crucial difference is the mean mechanical power output during the propulsion phase, which could be determined by intrinsic neuro-muscular mechanisms for power production. We measured M. vastus lateralis (VL) fascicle length changes and activation patterns and assessed the force–length, force–velocity and power–velocity potentials during the jumps. Compared with the SJ, the VL fascicles operated on a more favourable portion of the force–length curve (7% greater force potential, i.e. fraction of VL maximum force according to the force–length relationship) and more disadvantageous portion of the force–velocity curve (11% lower force potential, i.e. fraction of VL maximum force according to the force–velocity relationship) in the CMJ, indicating a reciprocal effect of force–length and force–velocity potentials for force generation. The higher muscle activation (15%) could therefore explain the moderately greater jump height (5%) in the CMJ. The mean fascicle-shortening velocity in the CMJ was closer to the plateau of the power–velocity curve, which resulted in a greater (15%) power–velocity potential (i.e. fraction of VL maximum power according to the power–velocity relationship). Our findings provide evidence for a cumulative effect of three different mechanisms—i.e. greater force–length potential, greater power–velocity potential and greater muscle activity—for an advantaged power production in the CMJ contributing to the marked difference in mean mechanical power (56%) compared with SJ.

Effects of pregnancy on cardiac function and myosin enzymology in the rat

1987 ◽  
Vol 252 (4) ◽  
pp. H846-H850 ◽  
Author(s):  
P. M. Buttrick ◽  
T. F. Schaible ◽  
A. Malhotra ◽  
S. Mattioli ◽  
J. Scheuer
Keyword(s):  
Cardiac Function ◽  
Cardiac Contractility ◽  
Volume Overload ◽  
Loading Conditions ◽  
Protein Biochemistry ◽  
Rat Hearts ◽  
Velocity Relationship ◽  
Force Velocity ◽  
In Vivo Loading

Previous studies of cardiac function during pregnancy, while suggesting that this condition is associated with improved myocardial contractility, have been biased by the altered in vivo loading conditions. Therefore, we have investigated intrinsic cardiac function and contractile protein biochemistry during pregnancy in isolated rat hearts under controlled loading conditions. Animals were impregnated and studied after 1 and 3 wk and 2-3 days postpartum (gestation 21 days). The data show that hearts from pregnant animals (at 3 wk) had improved contractile performance as manifested by an 11% increase in fractional shortening, a 20% increase in velocity of circumferential fiber shortening, and an upward-shifted force-velocity relationship. These findings were paralleled by a 16% increase in Ca2+-activated myosin and an 11% increase in actin-activated ATPase activities. Thus pregnancy in the rat is associated with slightly improved cardiac contractility and biochemistry. This may relate directly to the hormonal status of the pregnant animal or to the effects of chronic volume overload.

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