scholarly journals The pCa-tension and force-velocity characteristics of skinned fibres isolated from fish fast and slow muscles

1982 ◽  
Vol 333 (1) ◽  
pp. 421-449 ◽  
Author(s):  
J. D. Altringham ◽  
I. A. Johnston
Keyword(s):  
Skinned Fibres ◽  
Fast And Slow Muscles ◽  
Force Velocity

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 Effects of Temperature and Thermal Acclimation on Contractile Properties and Metabolism of Skeletal Muscle in the Flounder (Platichthys Flesus L.)

1986 ◽  
Vol 120 (1) ◽  
pp. 119-130 ◽  
Author(s):  
IAN A. JOHNSTON ◽  
ALELE WOKOMA
Keyword(s):  
Power Output ◽  
Contractile Properties ◽  
Temperature Adaptation ◽  
Evolutionary Strategies ◽  
Muscle Fibres ◽  
Skinned Fibres ◽  
Thermal Dependence ◽  
Tension Development ◽  
Platichthys Flesus ◽  
Force Velocity

Flounder (Platichthys flesus L.) were acclimated in sea water for 1–2 months toeither 5°C or 23°C (12h light: 12h dark photoperiod). Single fast muscle fibres were isolated from anterior ventral myotomes and skinned with detergent (Brij 58). Fibres were maximally activated and force-velocity (P-V) characteristics determined by step tension releases using an isotonic lever. Unloaded shortening speed was independently determined using the slack-testmethod. The contractile properties of flounder skinned fibres are not altered by temperature acclimation. Maximum isometric tension development has a low thermal dependence, Q10 = 1.2, increasing from 145 kNm−2 at 0°C to 200kNm −2 at 25°C. The force-velocity relationship becomes progressively less curved with decreasing temperature (higher values of Hill's constant a/P0) such that the thermal dependence of contraction velocity is significantly less at loads for optimum power output (Q10 = 1.3) than at zero load (Q10 = 2.0). Values for a/P0 are 0.27 at 0°C, 0.12 at 10°C and 0.08 at 25°C. Reductions in the curvature of the P-V relationshipwith decreasing temperature may represent an important mechanism for stabilizing muscle power output at low temperatures. Longer term metabolic adjustments to temperature were studied by determining maximal enzyme activities in fast and slow muscles (at 15°C). Activities of marker enzymes for mitochondrial metabolism (cytochrome oxidase), aerobic glucoseutilization (hexokinase) and fatty acid oxidation (carnitine palmitoyl transferase) are1.5-2.8 times higher in muscles of cold-acclimated compared to warm-acclimatedflounders. Increases in the activities of these enzymes with cold acclimation mayserve to offset the effects of low temperature on aerobic ATP supply. Glycolyticenzyme activities (phosphofructokinase, lactate dehydrogenase), however, aresimilar at both acclimation temperatures. The results are briefly discussed in relation to the ecology of the flounder and evolutionary strategies of temperature adaptation in teleosts.

scholarly journals Effects of plantar flexors training (force vs. velocity) on plantar flexion and squat jump force-velocity relationships

2019 ◽  
Vol 22 (sup1) ◽  
pp. S350-S351
Author(s):  
C. Giroux ◽  
R. Hager ◽  
J. Feugray ◽  
G. Lauby ◽  
S. Dorel ◽  
...  
Keyword(s):  
Plantar Flexion ◽  
Plantar Flexors ◽  
Squat Jump ◽  
Force Velocity

scholarly journals Eccentric Force-Velocity Characteristics during a Novel Squat Protocol in Trained Rugby Union Athletes—Pilot Study

2021 ◽  
Vol 6 (2) ◽  
pp. 32
Author(s):  
Conor McNeill ◽  
C. Martyn Beaven ◽  
Daniel T. McMaster ◽  
Nicholas Gill
Keyword(s):  
Pilot Study ◽  
Dynamic Performance ◽  
Intraclass Correlation ◽  
Rugby Union ◽  
Mean Velocity ◽  
Force Development ◽  
Back Squat ◽  
Force Velocity ◽  
Force Time ◽  
Change In Mean

Eccentric strength characteristics have been shown to be important factors in physical performance. Many eccentric tests have been performed in isolation or with supramaximal loading. The purpose of this study was to investigate within- and between- session reliability of an incremental eccentric back squat protocol. Force plates and a linear position transducer captured force-time-displacement data across six loading conditions, separated by at least seven days. The reliability of eccentric specific measurements was assessed using coefficient of variation (CV), change in mean, and intraclass correlation coefficient (ICC). Eccentric peak force demonstrated good ICC (≥0.82) and TE (≤7.3%) for each load. Variables based on mean data were generally less reliable (e.g., mean rate of force development, mean force, mean velocity). This novel protocol meets acceptable levels of reliability for different eccentric-specific measurements although the extent to which these variables affect dynamic performance requires further research.

scholarly journals Maximizing Acceleration and Change of Direction in Sport: A Case Series to Illustrate How the Force-Velocity Profile Provides Additional Information to That Derived from Linear Sprint Time

2021 ◽  
Vol 18 (11) ◽  
pp. 6140
Author(s):  
Andrés Baena-Raya ◽  
Manuel A. Rodríguez-Pérez ◽  
Pedro Jiménez-Reyes ◽  
Alberto Soriano-Maldonado
Keyword(s):  
Mechanical Properties ◽  
Case Series ◽  
Relevant Information ◽  
Maximal Power Output ◽  
Sprint Time ◽  
Change Of Direction ◽  
Training Interventions ◽  
Additional Information ◽  
Technical Report ◽  
Force Velocity

Sprint running and change of direction (COD) present similar mechanical demands, involving an acceleration phase in which athletes need to produce and apply substantial horizontal external force. Assessing the mechanical properties underpinning individual sprint acceleration might add relevant information about COD performance in addition to that obtained through sprint time alone. The present technical report uses a case series of three athletes with nearly identical 20 m sprint times but with different mechanical properties and COD performances. This makes it possible to illustrate, for the first time, a potential rationale for why the sprint force-velocity (FV) profile (i.e., theoretical maximal force (F0), velocity (V0), maximal power output (Pmax), ratio of effective horizontal component (RFpeak) and index of force application technique (DRF)) provides key information about COD performance (i.e., further to that derived from simple sprint time), which can be used to individualize training. This technical report provides practitioners with a justification to assess the FV profile in addition to sprint time when the aim is to enhance sprint acceleration and COD performance; practical interpretations and advice on how training interventions could be individualized based on the athletes’ differential sprint mechanical properties are also specified.

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