scholarly journals Muscle Belly Gearing Positively Affects the Force–Velocity and Power–Velocity Relationships During Explosive Dynamic Contractions

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrea Monte ◽  
Matteo Bertucco ◽  
Riccardo Magris ◽  
Paola Zamparo
Keyword(s):  
Vastus Lateralis ◽  
Angular Acceleration ◽  
Muscle Thickness ◽  
Knee Extensors ◽  
Shortening Velocity ◽  
Muscle Belly ◽  
Output Force ◽  
Dynamic Contractions ◽  
Force Velocity

Changes in muscle shape could play an important role during contraction allowing to circumvent some limits imposed by the fascicle force–velocity (F–V) and power–velocity (P–V) relationships. Indeed, during low-force high-velocity contractions, muscle belly shortening velocity could exceed muscle fascicles shortening velocity, allowing the muscles to operate at higher F–V and P–V potentials (i.e., at a higher fraction of maximal force/power in accordance to the F–V and P–V relationships). By using an ultrafast ultrasound, we investigated the role of muscle shape changes (vastus lateralis) in determining belly gearing (muscle belly velocity/fascicle velocity) and the explosive torque during explosive dynamic contractions (EDC) at angular accelerations ranging from 1000 to 4000°.s–2. By means of ultrasound and dynamometric data, the F–V and P–V relationships both for fascicles and for the muscle belly were assessed. During EDC, fascicle velocity, belly velocity, belly gearing, and knee extensors torque data were analysed from 0 to 150 ms after torque onset; the fascicles and belly F–V and P–V potentials were thus calculated for each EDC. Absolute torque decreased as a function of angular acceleration (from 80 to 71 Nm, for EDC at 1000 and 4000°.s–1, respectively), whereas fascicle velocity and belly velocity increased with angular acceleration (P < 0.001). Belly gearing increased from 1.11 to 1.23 (or EDC at 1000 and 4000°.s–1, respectively) and was positively corelated with the changes in muscle thickness and pennation angle (the changes in latter two equally contributing to belly gearing changes). For the same amount of muscle’s mechanical output (force or power), the fascicles operated at higher F–V and P–V potential than the muscle belly (e.g., P–V potential from 0.70 to 0.56 for fascicles and from 0.65 to 0.41 for the muscle belly, respectively). The present results experimentally demonstrate that belly gearing could play an important role during explosive contractions, accommodating the largest part of changes in contraction velocity and allowing the fascicle to operate at higher F–V and P–V potentials.

Can Hip Joint Position affect Quadriceps Muscle Responses during Knee Extension Exercise?

2020 ◽  
Vol 41 (13) ◽  
pp. 929-935
Author(s):  
Denis César Leite Vieira ◽  
Marco Aurélio Araujo Dourado ◽  
Lucas Ugliara ◽  
Joao Luiz Quagliotti Durigan ◽  
Brad J. Schoenfeld ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Muscle Thickness ◽  
Rectus Femoris ◽  
Peak Torque ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Knee Extensors ◽  
Work Output ◽  
Before And After ◽  
Knee Extension Exercise

AbstractThis study investigated the acute effects of seated and supine knee extension exercise on muscle swelling, torque, and work output. Twelve resistance-trained men performed two isokinetic concentric-only knee-extension training protocols at different hip positions in a counter-balanced order. They completed the knee extension exercise in the seated (hip angle at 85°) and supine (hip angle at 180°) positions. The torque and work output were assessed during each set. Moreover, muscle thickness of the middle and proximal vastus lateralis and rectus femoris were evaluated before and after each protocol and used as an indicator of muscle swelling. Middle rectus femoris and proximal vastus lateralis thickness increased significantly (p=0.01) with no difference between exercise variations. However, the middle vastus lateralis thickness increased (p=0.01) only after the seated knee extension exercise (~7%). Knee extensors’ peak torque and work output were approximately 8% higher (p=0.04) in the seated when compared to the supine hip position. There was a similar decrease in torque and work output throughout both protocols (p=0.98). In conclusion, seated knee extension exercises produced greater torque, work output, and muscle swelling in the vastus lateralis when compared to the supine knee extension exercise.

Regulation of energy liberation during steady sarcomere shortening

2005 ◽  
Vol 289 (5) ◽  
pp. H2176-H2182 ◽  
Author(s):  
Oren Tchaicheeyan ◽  
Amir Landesberg
Keyword(s):  
Energy Liberation ◽  
Free Calcium ◽  
Relative Role ◽  
Shortening Velocity ◽  
Velocity Relationship ◽  
Intracellular Free Calcium Concentration ◽  
Free Calcium Concentration ◽  
Strong Transition ◽  
Force Velocity

Energy liberation rate ( Ė) during steady muscle shortening is a monotonic increasing or biphasic function of the shortening velocity ( V). The study examines three plausible hypotheses for explaining the biphasic Ė-V relationship (EVR): 1) the cross-bridge (XB) turnover rate from non-force-generating (weak) to force-generating (strong) conformation decreases as V increases; 2) XB kinetics is determined by the number of strong XBs (XB -XB cooperativity); and 3) the affinity of troponin for calcium is modulated by the number of strong XBs (XB -Ca cooperativity). The relative role of the various energy-regulating mechanisms is not well defined. The hypotheses were tested by coupling calcium kinetics with XB cycling. All three hypotheses yield identical steady-state characteristics: 1) hyperbolic force-velocity relationship; 2) quasi-linear stiffness-force relationship; and 3) biphasic EVR, where Ė declines at high V due to decrease in the number of cycling XBs or in the weak-to-strong transition rate. The hypotheses differ in the ability to describe the existence of both monotonic and biphasic EVRs and in the effect of intracellular free calcium concentration ([Ca2+]i) on the EVR peak. Monotonic and biphasic EVRs with a shift in EVR peak to higher velocity at higher [Ca2+]i are obtained only by XB -Ca cooperativity. XB -XB cooperativity provides only biphasic EVRs. A direct effect of V on XB kinetics predicts that EVR peak is obtained at the same velocity independently of [Ca2+]i. The study predicts that measuring the dependence of the EVR on [Ca2+]i allows us to test the hypotheses and to identify the dominant energy-regulating mechanism. The established XB -XB and XB -Ca mechanisms provide alternative explanations to the various reported EVRs.

Associations of the Force-velocity Profile with Isometric Strength and Neuromuscular Factors

2018 ◽  
Vol 39 (13) ◽  
pp. 984-994 ◽  
Author(s):  
Antonio Morales-Artacho ◽  
Amador Ramos ◽  
Alejandro Pérez-Castilla ◽  
Paulino Padial ◽  
Javier Argüelles-Cienfuegos ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Correlation Coefficients ◽  
Knee Extension ◽  
Pennation Angle ◽  
Muscle Architecture ◽  
Isometric Strength ◽  
Knee Extensors ◽  
Fascicle Length ◽  
Force Velocity ◽  
Isometric Torque

AbstractWe aimed to explore relationships between the force-velocity (FV) profile and the isometric muscle torque performance during a knee extension task. The FV profile (force-intercept [F0], velocity-intercept [V0], maximum power [Pmax], and FV slope) during the countermovement jump (CMJ) exercise and isometric maximum voluntary torque (MVIC) and explosive voluntary torque production were assessed in 43 participants. Electromyography (EMG) was recorded during the isometric assessments and resting muscle architecture measurements were also performed (quadriceps thickness, vastus lateralis pennation angle and fascicle length). Pearson’s correlation coefficients were computed to assess bivariate relationships between the FV profile, isometric torque, EMG activation and muscle architecture. F0 predictions from neuromuscular measurements were assessed through multiple linear regression. Associations of F0 and Pmax with isometric torque increased from explosive to MVIC torque (r≥0.47; P<0.05). Significant associations were found between muscle architecture and F0 and Pmax (r≥0.69; P<0.05), while V0 and FV slope were unrelated (r≤0.27; P>0.05). Quadriceps thickness and VL pennation angle explained ~62% of F0 variance. In conclusion, the knee extensors maximal isometric strength and their morphological architecture are strongly related to F0 estimated from a CMJ FV profile test.

scholarly journals The force–length–velocity potential of the human soleus muscle is related to the energetic cost of running

2019 ◽  
Vol 286 (1917) ◽  
pp. 20192560 ◽  
Author(s):  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Alessandro Santuz ◽  
Adamantios Arampatzis
Keyword(s):  
Soleus Muscle ◽  
Velocity Potential ◽  
Running Economy ◽  
Energetic Cost ◽  
Shortening Velocity ◽  
Optimal Length ◽  
Muscle Belly ◽  
Work Production ◽  
Force Velocity ◽  
Force Potential

According to the force–length–velocity relationships, the muscle force potential is determined by the operating length and velocity, which affects the energetic cost of contraction. During running, the human soleus muscle produces mechanical work through active shortening and provides the majority of propulsion. The trade-off between work production and alterations of the force–length and force–velocity potentials (i.e. fraction of maximum force according to the force–length–velocity curves) might mediate the energetic cost of running. By mapping the operating length and velocity of the soleus fascicles onto the experimentally assessed force–length and force–velocity curves, we investigated the association between the energetic cost and the force–length–velocity potentials during running. The fascicles operated close to optimal length (0.90 ± 0.10 L 0 ) with moderate velocity (0.118 ± 0.039 V max [maximum shortening velocity]) and, thus, with a force–length potential of 0.92 ± 0.07 and a force–velocity potential of 0.63 ± 0.09. The overall force–length–velocity potential was inversely related ( r = −0.52, p = 0.02) to the energetic cost, mainly determined by a reduced shortening velocity. Lower shortening velocity was largely explained ( p < 0.001, R 2 = 0.928) by greater tendon gearing, shorter Achilles tendon lever arm, greater muscle belly gearing and smaller ankle angle velocity. Here, we provide the first experimental evidence that lower shortening velocities of the soleus muscle improve running economy.

The Effect of External Compression on the Mechanics of Muscle Contraction

2013 ◽  
Vol 29 (3) ◽  
pp. 360-364 ◽  
Author(s):  
James M. Wakeling ◽  
Meghan Jackman ◽  
Ana I. Namburete
Keyword(s):  
Muscle Thickness ◽  
Muscle Performance ◽  
Medial Gastrocnemius ◽  
Shortening Velocity ◽  
Fascicle Length ◽  
External Compression ◽  
Muscle Belly ◽  
Compression Bandages ◽  
Muscle Fascicle ◽  
Angular Velocities

The velocity at which a muscle fascicle will shorten, and hence the force that it can develop, depends on its gearing within the muscle belly. Muscle fascicle length depends on both its pennation and the thickness of the muscle. It was expected that external compression would reduce the muscle thickness and pennation and thus cause a reduction to the gearing of the fascicles relative to the muscle belly. Structural properties of the medial gastrocnemius muscle were visualized using B-mode ultrasound in six subjects. Measurements were taken during cyclical isotonic contractions at three different ankle torques and with the application of no, one, or two elastic compression bandages to the lower leg. Ankle torques and angular velocities were unaffected by the external compression. External compression did, however, reduce the muscle thickness and the fascicle pennation and resulted in a decrease in the gearing within the muscle belly. Reductions in gearing would result in an increase in the muscle fascicle shortening velocity that would reduce the force-generating potential of the fascicles. It is suggested that externally applied compression should not be considered a way to enhance muscle performance when based on the structural mechanics.

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.

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

Free radicals in hypoxic rat diaphragm contractility: no role for xanthine oxidase

2001 ◽  
Vol 281 (6) ◽  
pp. L1402-L1412 ◽  
Author(s):  
Leo M. A. Heunks ◽  
Herwin A. Machiels ◽  
Ronney de Abreu ◽  
Xiao Ping Zhu ◽  
Henricus F. M. van der Heijden ◽  
...  
Keyword(s):  
Free Radicals ◽  
Xanthine Oxidase ◽  
Power Output ◽  
Harmful Effect ◽  
Force Generation ◽  
Muscle Performance ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Contraction Pattern

Recent evidence indicates that hypoxia enhances the generation of oxidants. Little is known about the role of free radicals in contractility of the rat diaphragm during hypoxia. We hypothesized that antioxidants improve contractility of the hypoxic rat diaphragm and that xanthine oxidase (XO) is an important source of free radicals in the hypoxic diaphragm. The effects of N-acetylcysteine (NAC; 18 mM), Tiron (10 mM), and the XO inhibitor allopurinol (250 μM) were studied on isometric and isotonic force generation during hypoxia (Po 2 ∼7 kPa). NAC and Tiron decreased maximal force generation, slowed the shortening velocity, and decreased the power output. Fatigue rate was decreased in the presence of either NAC or Tiron. Allopurinol did not alter the contractility or fatigability of the diaphragm. During hyperoxia (Po 2 ∼85 kPa), neither NAC nor allopurinol affected the contractility or fatigability of the diaphragm. Thus free radicals play a significant role in diaphragm contractility during hypoxia. Whether antioxidants exert a beneficial or harmful effect on muscle performance depends on the contraction pattern of the muscle. Free radicals generated by XO do not play a role in diaphragm contractility during either hypoxia or hyperoxia.

Central and peripheral contributions to neuromuscular fatigue induced by a 24-h treadmill run

2010 ◽  
Vol 108 (5) ◽  
pp. 1224-1233 ◽  
Author(s):  
Vincent Martin ◽  
Hugo Kerhervé ◽  
Laurent A. Messonnier ◽  
Jean-Claude Banfi ◽  
André Geyssant ◽  
...  
Keyword(s):  
Compound Muscle Action Potential ◽  
Vastus Lateralis ◽  
Low Frequency ◽  
Force Production ◽  
Neuromuscular Fatigue ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Function Evaluation ◽  
Central Component ◽  
Low Frequency Fatigue

This experiment investigated the fatigue induced by a 24-h running exercise (24TR) and particularly aimed at testing the hypothesis that the central component would be the main mechanism responsible for neuromuscular fatigue. Neuromuscular function evaluation was performed before, every 4 h during, and at the end of the 24TR on 12 experienced ultramarathon runners. It consisted of a determination of the maximal voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), the maximal voluntary activation (%VA) of the KE and PF, and the maximal compound muscle action potential amplitude (Mmax) on the soleus and vastus lateralis. Tetanic stimulations also were delivered to evaluate the presence of low-frequency fatigue and the KE maximal muscle force production ability. Strength loss occurred throughout the exercise, with large changes observed after 24TR in MVC for both the KE and PF muscles (−40.9 ± 17.0 and −30.3 ± 12.5%, respectively; P < 0.001) together with marked reductions of %VA (−33.0 ± 21.8 and −14.8 ± 18.9%, respectively; P < 0.001). A reduction of Mmax amplitude was observed only on soleus, and no low-frequency fatigue was observed for any muscle group. Finally, KE maximal force production ability was reduced to a moderate extent at the end of the 24TR (−10.2%; P < 0.001), but these alterations were highly variable ( ± 15.7%). These results suggest that central factors are mainly responsible for the large maximal muscle torque reduction after ultraendurance running, especially on the KE muscles. Neural drive reduction may have contributed to the relative preservation of peripheral function and also affected the evolution of the running speed during the 24TR.

scholarly journals Vitamin and mineral supplementation effect on muscular activity and cycling efficiency in master athletes

2010 ◽  
Vol 35 (3) ◽  
pp. 251-260 ◽  
Author(s):  
Julien Louis ◽  
Christophe Hausswirth ◽  
François Bieuzen ◽  
Jeanick Brisswalter
Keyword(s):  
Slow Component ◽  
Vastus Lateralis ◽  
Muscular Activity ◽  
Knee Extensors ◽  
Emg Activity ◽  
Master Athletes ◽  
Double Blind ◽  
Mineral Complex ◽  
Cycling Efficiency ◽  
Fatiguing Exercise

The influence of vitamin and mineral complex supplementation on muscular activity and cycling efficiency was examined in elderly endurance-trained master athletes during a heavy cycling trial. Master athletes were randomly assigned in a double-blind process to 1 of 2 treatment groups: antioxidant supplementation (n = 8: As group) or placebo (n = 8: Pl group) for 21 days. After that time, each subject had to perform a 10-min session of cycling on a cycloergometer at a heavy constant intensity. Twenty-four to 48 h after this session, subjects performed an isometric maximal voluntary contraction before and immediately after a fatiguing strength training (leg press exercise) and the same 10-min cycling test after fatigue. Isometric maximal voluntary force (MVF) of knee extensors was assessed before and after fatigue. Electromyographic (EMG) activity of the vastus medialis, the vastus lateralis (VL), and the biceps femoris was recorded with surface EMG. The knee-extensors MVF after the fatiguing exercise was reduced in similar proportions for both groups (As, –10.9%; Pl, –11.3%, p < 0.05). This MVF loss was associated with a significant reduction in EMG frequency parameters for both groups, with a lower decrease for the As group. Muscular activity and cycling efficiency during the cycling bouts were affected by the treatment. Cycling efficiency decreased significantly and the oxygen uptake slow component was higher after the fatiguing exercise for both groups. Furthermore, a decrease in cycling efficiency was associated with an increase in VL activity. However, these changes were significantly lower for the As group. The results of the present study indicate an overall positive effect of vitamin and mineral complex supplementation on cycling efficiency after fatigue, in the endurance-trained elderly.

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