scholarly journals Why is the force-velocity relationship in leg press tasks quasi-linear rather than hyperbolic?

2012 ◽  
Vol 112 (12) ◽  
pp. 1975-1983 ◽  
Author(s):  
Maarten F. Bobbert
Keyword(s):  
External Force ◽  
Power Output ◽  
Muscle Force ◽  
Muscle Power ◽  
Leg Length ◽  
Leg Extension ◽  
Leg Press ◽  
Velocity Relationship ◽  
Force Velocity ◽  
The Relationship

Force-velocity relationships reported in the literature for functional tasks involving a combination of joint rotations tend to be quasi-linear. The purpose of this study was to explain why they are not hyperbolic, like Hill's relationship. For this purpose, a leg press task was simulated with a musculoskeletal model of the human leg, which had stimulation of knee extensor muscles as only independent input. In the task the ankles moved linearly, away from the hips, against an imposed external force that was reduced over contractions from 95 to 5% of the maximum isometric value. Contractions started at 70% of leg length, and force and velocity values were extracted when 80% of leg length was reached. It was shown that the relationship between leg extension velocity and external force was quasi-linear, while the relationship between leg extension velocity and muscle force was hyperbolic. The discrepancy was explained by the fact that segmental dynamics canceled more and more of the muscle force as the external force was further reduced and velocity became higher. External power output peaked when the imposed external force was ∼50% of maximum, while muscle power output peaked when the imposed force was only ∼15% of maximum; in the latter case ∼70% of muscle power was buffered by the leg segments. According to the results of this study, there is no need to appeal to neural mechanisms to explain why, in leg press tasks, the force-velocity relationship is quasi-linear rather than hyperbolic.

scholarly journals Effects of cross-bridge compliance on the force-velocity relationship and muscle power output

PLoS ONE ◽  
2017 ◽  
Vol 12 (12) ◽  
pp. e0190335 ◽  
Author(s):  
Axel J. Fenwick ◽  
Alexander M. Wood ◽  
Bertrand C. W. Tanner
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Cross Bridge ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Muscle Power Output

Dissecting muscle power output

1999 ◽  
Vol 202 (23) ◽  
pp. 3369-3375 ◽  
Author(s):  
R.K. Josephson
Keyword(s):  
Time Course ◽  
Muscle Activation ◽  
Muscle Force ◽  
Muscle Power ◽  
Muscle Length ◽  
Velocity Relationship ◽  
Shortening Deactivation ◽  
Force Velocity ◽  
Work Done ◽  
Kinetics Of

The primary determinants of muscle force throughout a shortening-lengthening cycle, and therefore of the net work done during the cycle, are (1) the shortening or lengthening velocity of the muscle and the force-velocity relationship for the muscle, (2) muscle length and the length-tension relationship for the muscle, and (3) the pattern of stimulation and the time course of muscle activation following stimulation. In addition to these primary factors, there are what are termed secondary determinants of force and work output, which arise from interactions between the primary determinants. The secondary determinants are length-dependent changes in the kinetics of muscle activation, and shortening deactivation, the extent of which depends on the work that has been done during the preceding shortening. The primary and secondary determinants of muscle force and work are illustrated with examples drawn from studies of crustacean muscles.

scholarly journals Temperature and the Force-Velocity Relationship of Live Muscle Fibres from the Teleost Myoxocephalus Scorpius

1989 ◽  
Vol 144 (1) ◽  
pp. 437-448 ◽  
Author(s):  
KAREN S. LANGFELD ◽  
JOHN D. ALTRINGHAM ◽  
IAN A. JOHNSTON
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Muscle Fibres ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Myoxocephalus Scorpius ◽  
Relationship Of ◽  
Myotomal Muscle ◽  
Best Fit ◽  
Tetanic Tension

Small bundles of fast fibres were isolated from the myotomal muscle of the teleost Myoxocephalus scorpius. The temperature-dependence of isometric contractile properties and the force-velocity (P-V) relationship were studied. Fibres were found to deteriorate above 18°C, and the force plateau during tetanic stimulation was not maintained above 15°C. Twitch and tetanic tension (P0) showed optima at around 8°C. Force-velocity curves were fitted using either Hill's hyperbolic equation or a hyperbolic-linear equation (hyp-lin). The best fit to the data was provided by the hyp-lin equation, which gave consistently higher values for unloaded contraction velocity (Vmax): 4.3, 8.1 and 9.5 muscle lengths s−1 at 1, 8 and 12°C, respectively. The P-V relationship was found to become progressively more curved at higher temperatures. Muscle power output calculated from the hyp-lin equation was 123 W kg−1 at 1°C and 256 W kg−1 at 8°C. Curves normalized for P0 and Vmax at each temperature show that the change in curvature is sufficient to increase the relative power output of the muscle by around 15% on decreasing the temperature from 8 to 1°C.

Lower Limb Force, Velocity, Power Capabilities during Leg Press and Squat Movements

2017 ◽  
Vol 38 (14) ◽  
pp. 1083-1089 ◽  
Author(s):  
Johnny Padulo ◽  
Gian Migliaccio ◽  
Luca Ardigò ◽  
Bruno Leban ◽  
Marco Cosso ◽  
...  
Keyword(s):  
Velocity Profile ◽  
Effect Size ◽  
Power Output ◽  
Lower Limb ◽  
Maximal Power ◽  
Maximal Power Output ◽  
Optimal Velocity ◽  
Leg Press ◽  
Maximal Force ◽  
Force Velocity

AbstractThe aim was to compare lower-limb power, force, and velocity capabilities between squat and leg press movements. Ten healthy sportsmen performed ballistic lower-limb push-offs against 5-to-12 different loads during both the squat and leg press. Individual linear force-velocity and polynomial power-velocity relationships were determined for both movements from push-off mean force and velocity measured continuously with a pressure sensor and linear encoder. Maximal power output, theoretical maximal force and velocity, force-velocity profile and optimal velocity were computed. During the squat, maximal power output (17.7±3.59 vs. 10.9±1.39 W·kg−1), theoretical maximal velocity (1.66±0.29 vs. 0.88±0.18 m·s−1), optimal velocity (0.839±0.144 vs. 0.465±0.107 m·s−1), and force-velocity profile (−27.2±8.5 vs. −64.3±29.5 N·s·m−1·kg−1) values were significantly higher than during the leg press (p=0.000, effect size=1.72–3.23), whereas theoretical maximal force values (43.1±8.6 vs. 51.9±14.0 N·kg−1, p=0.034, effect size=0.75) were significantly lower. The mechanical capabilities of the lower-limb extensors were different in the squat compared with the leg press with higher maximal power due to much higher velocity capabilities (e.g. ability to produce force at high velocities) even if moderately lower maximal force qualities.

scholarly journals Power Output and Force-Velocity Relationship of Live Fibres from White Myotomal Muscle of the Dogfish, Scyliorhinus Canicula

1988 ◽  
Vol 140 (1) ◽  
pp. 187-197 ◽  
Author(s):  
N. A. CURTIN ◽  
R. C. WOLEDGE
Keyword(s):  
Power Output ◽  
Maximum Velocity ◽  
Muscle Fibres ◽  
Fish Length ◽  
Skinned Fibres ◽  
Step Method ◽  
Velocity Relationship ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Myotomal Muscle

The relationship between force and velocity of shortening and between power and velocity were examined for myotomal muscle fibre bundles from the dogfish. The maximum velocity of shortening, mean value 4.8 ± 0.2 μms−1 half sarcomere−1 (±S.E.M., N = 13), was determined by the ‘slack step’ method (Edman, 1979) and was found to be independent of fish length. The force-velocity relationship was hyperbolic, except at the high-force end where the observations were below the hyperbola fitted to the rest of the data. The maximum power output was 91 ± 14 W kg−1 wet mass (±S.E.M., N = 7) at a velocity of shortening of 1.3 ± 0.13μms−1 halfsarcomere−1 (±S.E.M., N = 7). This power output is considerably higher than that previously reported for skinned fibres (Bone et al. 1986). Correspondingly the force-velocity relationship is less curved for intact fibres than for skinned fibres. The maximum swimming speed (normalized for fish length) predicted from the observed power output of the muscle fibres decreased with increasing fish size; it ranged from 12.9 to 7.8 fish lengths s−1 for fish 0155–0.645m in length.

scholarly journals The effects of inorganic phosphate on muscle force development and energetics: challenges in modelling related to experimental uncertainties

2019 ◽  
Author(s):  
Alf Månsson
Keyword(s):  
Inorganic Phosphate ◽  
Muscle Force ◽  
Isometric Force ◽  
Shortening Velocity ◽  
Apparent Contradiction ◽  
Sequence Of Events ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Cross Bridges ◽  
Experimental Findings

Abstract Muscle force and power are developed by myosin cross-bridges, which cyclically attach to actin, undergo a force-generating transition and detach under turnover of ATP. The force-generating transition is intimately associated with release of inorganic phosphate (Pi) but the exact sequence of events in relation to the actual Pi release step is controversial. Details of this process are reflected in the relationships between [Pi] and the developed force and shortening velocity. In order to account for these relationships, models have proposed branched kinetic pathways or loose coupling between biochemical and force-generating transitions. A key hypothesis underlying the present study is that such complexities are not required to explain changes in the force–velocity relationship and ATP turnover rate with altered [Pi]. We therefore set out to test if models without branched kinetic paths and Pi-release occurring before the main force-generating transition can account for effects of varied [Pi] (0.1–25 mM). The models tested, one assuming either linear or non-linear cross-bridge elasticity, account well for critical aspects of muscle contraction at 0.5 mM Pi but their capacity to account for the maximum power output vary. We find that the models, within experimental uncertainties, account for the relationship between [Pi] and isometric force as well as between [Pi] and the velocity of shortening at low loads. However, in apparent contradiction with available experimental findings, the tested models produce an anomalous force–velocity relationship at elevated [Pi] and high loads with more than one possible velocity for a given load. Nevertheless, considering experimental uncertainties and effects of sarcomere non-uniformities, these discrepancies are insufficient to refute the tested models in favour of more complex alternatives.

Effects of cluster training sets on muscle power and force–velocity relationship in postmenopausal women

2019 ◽  
Vol 16 (2) ◽  
pp. 257-265
Author(s):  
Marcelo A. S. Carneiro ◽  
Gersiel N. de Oliveira Júnior ◽  
Jairo F. R. de Sousa ◽  
Samarita B. Santagnello ◽  
Markus V. C. Souza ◽  
...  
Keyword(s):  
Postmenopausal Women ◽  
Muscle Power ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Training Sets

PECTORALIS MUSCLE FORCE AND POWER OUTPUT DURING FLIGHT IN THE STARLING

1992 ◽  
Vol 164 (1) ◽  
pp. 1-18 ◽  
Author(s):  
ANDREW A. BIEWENER ◽  
KENNETH P. DIAL ◽  
G. E. GOSLOW
Keyword(s):  
Power Output ◽  
Muscle Force ◽  
Muscle Power ◽  
Isometric Force ◽  
Attachment Site ◽  
Bone Strain ◽  
Pectoralis Muscle ◽  
Live Animal ◽  
Level Flight ◽  
Length Changes

Force recordings of the pectoralis muscle of European starlings have been made in vivo during level flight in a wind tunnel, based on bone strain recordings at the muscle's attachment site on the humerus (deltopectoral crest). This represents the first direct measurement of muscle force during activity in a live animal based on calibrated bone strain recordings. Our force measurements confirm earlier electromyographic data and show that the pectoralis begins to develop force during the final one-third of the upstroke, reaches a maximal level halfway through the downstroke, and sustains force throughout the downstroke. Peak forces generated by the pectoralis during level flight at a speed estimated to be 13.7ms−1 averaged 6.4N (28% of maximal isometric force), generating a mean mass-specific muscle power output of 104 W kg−1. Combining our data for the power output of the pectoralis muscle with data for the metabolic power of starlings flying at a similar speed yields an overall flight efficiency of 13 %. The force recordings and length changes of the muscle, based on angular displacements of the humerus, indicate that the pectoralis muscle undergoes a lengthening--shortening contraction sequence during its activation and that, in addition to lift and thrust generation, overcoming wing inertia is probably an important function of this muscle in flapping flight.

scholarly journals Muscle Force-Velocity Relationships Observed in Four Different Functional Tests

2017 ◽  
Vol 56 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Milena Z. Zivkovic ◽  
Sasa Djuric ◽  
Ivan Cuk ◽  
Dejan Suzovic ◽  
Slobodan Jaric
Keyword(s):  
Correlation Coefficients ◽  
Maximum Force ◽  
Functional Movement ◽  
Median Correlation ◽  
Velocity Relationship ◽  
Relationship Model ◽  
Generating Capacity ◽  
Force Velocity ◽  
Vertical Jumps ◽  
The Relationship

AbstractThe aims of the present study were to investigate the shape and strength of the force-velocity relationships observed in different functional movement tests and explore the parameters depicting force, velocity and power producing capacities of the tested muscles. Twelve subjects were tested on maximum performance in vertical jumps, cycling, bench press throws, and bench pulls performed against different loads. Thereafter, both the averaged and maximum force and velocity variables recorded from individual trials were used for force–velocity relationship modeling. The observed individual force-velocity relationships were exceptionally strong (median correlation coefficients ranged from r = 0.930 to r = 0.995) and approximately linear independently of the test and variable type. Most of the relationship parameters observed from the averaged and maximum force and velocity variable types were strongly related in all tests (r = 0.789-0.991), except for those in vertical jumps (r = 0.485-0.930). However, the generalizability of the force-velocity relationship parameters depicting maximum force, velocity and power of the tested muscles across different tests was inconsistent and on average moderate. We concluded that the linear force-velocity relationship model based on either maximum or averaged force-velocity data could provide the outcomes depicting force, velocity and power generating capacity of the tested muscles, although such outcomes can only be partially generalized across different muscles.

Calculating ideal bat weight using the muscle force-velocity relationship

1989 ◽  
Vol 22 (10) ◽  
pp. 1045
Author(s):  
Yiannakis Laouris ◽  
William J. Karnavas ◽  
A. Terry Bahill
Keyword(s):  
Muscle Force ◽  
Velocity Relationship ◽  
Force Velocity
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