CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - MECHANICAL POWER OUTPUT

1994 ◽  
Vol 187 (1) ◽  
pp. 295-303 ◽  
Author(s):  
R Josephson ◽  
D Stokes
Keyword(s):  
Power Output ◽  
High Frequency ◽  
Carcinus Maenas ◽  
Mechanical Power ◽  
Abductor Muscle ◽  
Mechanical Power Output ◽  
Loop Technique ◽  
Number Of Cycles ◽  
Work Loop

The mechanical power output during oscillatory contraction was determined for the flagellum abductor muscle of the crab Carcinus maenas using the work loop technique. Measurements were made at 10 Hz, which is the normal operating frequency of the muscle. The temperature was 15 °C. Increasing the number of stimuli per cycle (given at an interstimulus interval of 3.3 ms) decreased the number of cycles required to reach a work plateau and increased the work per cycle at the plateau to a maximum at 4­5 stimuli per cycle. The maximum mechanical power output was 9.7 W kg-1 muscle (about 26 W kg-1 myofibril). The optimum strain for work output (5.7 %) was close to the estimated muscle strain in vivo (5.2 %).

Early effects of ageing on the mechanical performance of isolated locomotory (EDL) and respiratory (diaphragm) skeletal muscle using the work-loop technique

2014 ◽  
Vol 307 (6) ◽  
pp. R670-R684 ◽  
Author(s):  
Jason Tallis ◽  
Rob S. James ◽  
Alexander G. Little ◽  
Val M. Cox ◽  
Michael J. Duncan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Power Output ◽  
Muscle Performance ◽  
Maximal Power ◽  
Maximal Power Output ◽  
Age Related ◽  
Loop Technique ◽  
Edl Muscle ◽  
Work Loop

Previous isolated muscle studies examining the effects of ageing on contractility have used isometric protocols, which have been shown to have poor relevance to dynamic muscle performance in vivo. The present study uniquely uses the work-loop technique for a more realistic estimation of in vivo muscle function to examine changes in mammalian skeletal muscle mechanical properties with age. Measurements of maximal isometric stress, activation and relaxation time, maximal power output, and sustained power output during repetitive activation and recovery are compared in locomotory extensor digitorum longus (EDL) and core diaphragm muscle isolated from 3-, 10-, 30-, and 50-wk-old female mice to examine the early onset of ageing. A progressive age-related reduction in maximal isometric stress that was of greater magnitude than the decrease in maximal power output occurred in both muscles. Maximal force and power developed earlier in diaphragm than EDL muscle but demonstrated a greater age-related decline. The present study indicates that ability to sustain skeletal muscle power output through repetitive contraction is age- and muscle-dependent, which may help rationalize previously reported equivocal results from examination of the effect of age on muscular endurance. The age-related decline in EDL muscle performance is prevalent without a significant reduction in muscle mass, and biochemical analysis of key marker enzymes suggests that although there is some evidence of a more oxidative fiber type, this is not the primary contributor to the early age-related reduction in muscle contractility.

scholarly journals Effects of high-frequency initial pulses and posttetanic potentiation on power output of skeletal muscle

2000 ◽  
Vol 88 (1) ◽  
pp. 35-40 ◽  
Author(s):  
F. Abbate ◽  
A. J. Sargeant ◽  
P. W. L. Verdijk ◽  
A. de Haan
Keyword(s):  
Power Output ◽  
High Frequency ◽  
Peak Power ◽  
Medial Gastrocnemius ◽  
Mechanical Power ◽  
Posttetanic Potentiation ◽  
Concentric Contractions ◽  
Mechanical Power Output ◽  
Stimulation Of

The effects of high-frequency initial pulses (HFIP) and posttetanic potentiation on mechanical power output during concentric contractions were examined in the in situ medial gastrocnemius of the rat with an intact origin on the femur and blood supply. Stimulation of the muscle was performed via the severed sciatic nerve. In the experiments, HFIP or the potentiating tetanus was followed by a stimulation of 80, 120, or 200 Hz. The results showed that both HFIP and the tetanus increased power output at high contraction velocities (>75 mm/s) when followed by a train of 80 or 120 Hz (200 Hz resulted in no effects). Mechanical power output was increased maximally by HFIP to 120 and 168% by the tetanus. Furthermore, when HFIP or the tetanus were followed by a train of 80 Hz, the peak power in the power-velocity curve tended to be shifted to a higher velocity.

scholarly journals TEMPERATURE, MUSCLE POWER OUTPUT AND LIMITATIONS ON BURST LOCOMOTOR PERFORMANCE OF THE LIZARD DIPSOSAURUS DORSALIS

1993 ◽  
Vol 174 (1) ◽  
pp. 185-197 ◽  
Author(s):  
S. J. Swoap ◽  
T. P. Johnson ◽  
R. K. Josephson ◽  
A. F. Bennett
Keyword(s):  
Power Output ◽  
Maximum Power ◽  
Stride Frequency ◽  
Cycle Frequency ◽  
Maximum Power Output ◽  
Mechanical Power Output ◽  
Cycling Frequency ◽  
Loop Technique ◽  
Fast Twitch

The mechanical power output of fast-twitch fibres from the iliofibularis of the lizard Dipsosaurus dorsalis was measured over a broad body temperature range using the oscillatory work-loop technique. The optimal cycling frequency, that frequency at which mechanical power output is maximal, increases with temperature from 3.3 Hz at 15°C to 20.1 Hz at 42°C. Maximum power output increases with temperature, from 20 W kg-1 at 15°C to 154 W kg-1 at 42°C, the largest power output yet measured using the work-loop technique. At low temperatures (15°C and 22°C), stride frequency during burst running is nearly identical to the optimal cycling frequency for in vitro power output, suggesting that maximum power output may limit hindlimb cycle frequency in vivo. However, at higher temperatures (35°C and 42°C), the optimal cycling frequency of the isolated muscle is significantly higher than the burst stride frequency, demonstrating that contractile events no longer limit hindlimb cycle frequency. At higher temperatures, it is thus unlikely that the fast-twitch fibres of this muscle in vivo attain their potential for maximum power output.

scholarly journals Calcium signalling indicates bilateral power balancing in the Drosophila flight muscle during manoeuvring flight

2013 ◽  
Vol 10 (82) ◽  
pp. 20121050 ◽  
Author(s):  
Fritz-Olaf Lehmann ◽  
Dimitri A. Skandalis ◽  
Ruben Berthé
Keyword(s):  
Power Output ◽  
Mechanical Power ◽  
Flapping Wings ◽  
Muscle Fibres ◽  
Bilateral Control ◽  
Calcium Activation ◽  
Mechanical Power Output ◽  
Power Balancing ◽  
Muscle Calcium

Manoeuvring flight in animals requires precise adjustments of mechanical power output produced by the flight musculature. In many insects such as fruit flies, power generation is most likely varied by altering stretch-activated tension, that is set by sarcoplasmic calcium levels. The muscles reside in a thoracic shell that simultaneously drives both wings during wing flapping. Using a genetically expressed muscle calcium indicator, we here demonstrate in vivo the ability of this animal to bilaterally adjust its calcium activation to the mechanical power output required to sustain aerodynamic costs during flight. Motoneuron-specific comparisons of calcium activation during lift modulation and yaw turning behaviour suggest slightly higher calcium activation for dorso-longitudinal than for dorsoventral muscle fibres, which corroborates the elevated need for muscle mechanical power during the wings’ downstroke. During turning flight, calcium activation explains only up to 54 per cent of the required changes in mechanical power, suggesting substantial power transmission between both sides of the thoracic shell. The bilateral control of muscle calcium runs counter to the hypothesis that the thorax of flies acts as a single, equally proportional source for mechanical power production for both flapping wings. Collectively, power balancing highlights the precision with which insects adjust their flight motor to changing energetic requirements during aerial steering. This potentially enhances flight efficiency and is thus of interest for the development of technical vehicles that employ bioinspired strategies of power delivery to flapping wings.

The efficiency of frog ventricular muscle.

1994 ◽  
Vol 197 (1) ◽  
pp. 143-164
Author(s):  
D A Syme
Keyword(s):  
Power Output ◽  
Muscle Length ◽  
Length Change ◽  
Mechanical Power ◽  
Muscle Fibres ◽  
Cycle Frequency ◽  
Energy Equivalent ◽  
Mechanical Power Output ◽  
Loop Technique ◽  
The Cost

Mechanical power and oxygen consumption (VO2) were measured simultaneously from isolated segments of trabecular muscle from the frog (Rana pipiens) ventricle. Power was measured using the work-loop technique, in which bundles of trabeculae were subjected to cyclic, sinusoidal length change and phasic stimulation. VO2 was measured using a polarographic O2 electrode. Both mechanical power and VO2 increased with increasing cycle frequency (0.4-0.9 Hz), with increasing muscle length and with increasing strain (= shortening, range 0-25% of resting length). Net efficiency, defined as the ratio of mechanical power output to the energy equivalent of the increase in VO2 above resting level, was independent of cycle frequency and increased from 8.1 to 13.0% with increasing muscle length, and from 0 to 13% with increasing strain, in the ranges examined. Delta efficiency, defined as the slope of the line relating mechanical power output to the energy equivalent of VO2, was 24-43%, similar to that reported from studies using intact hearts. The cost of increasing power output was greater if power was increased by increasing cycle frequency or muscle length than if it was increased by increasing strain. The results suggest that the observation that pressure-loading is more costly than volume-loading is inherent to these muscle fibres and that frog cardiac muscle is, if anything, less efficient than most skeletal muscles studied thus far.

scholarly journals On the mechanical power output comparisons of cone dielectric elastomer actuators

2021 ◽  
pp. 1-1
Author(s):  
Chongjing Cao ◽  
Lijin Chen ◽  
Wenke Duan ◽  
Thomas L. Hill ◽  
Bo Li ◽  
...  
Keyword(s):  
Power Output ◽  
Dielectric Elastomer ◽  
Mechanical Power ◽  
Dielectric Elastomer Actuators ◽  
Mechanical Power Output

scholarly journals Effect of Accommodating Elastic Bands on Mechanical Power Output during Back Squats

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 151 ◽  
Author(s):  
Takafumi Kubo ◽  
Kuniaki Hirayama ◽  
Nobuhiro Nakamura ◽  
Mitsuru Higuchi
Keyword(s):  
Power Output ◽  
Random Order ◽  
Mechanical Power ◽  
Muscular Force ◽  
Force Output ◽  
Elastic Band ◽  
Free Weight ◽  
Mechanical Power Output ◽  
Elastic Bands ◽  
Acceleration And Deceleration

The aim of this study was to investigate whether accommodating elastic bands with barbell back squats (BSQ) increase muscular force during the deceleration subphase. Ten healthy men (mean ± standard deviation: Age: 23 ± 2 years; height: 170.5 ± 3.7 cm; mass: 66.7 ± 5.4 kg; and BSQ one repetition maximum (RM): 105 ± 23.1 kg; BSQ 1RM/body mass: 1.6 ± 0.3) were recruited for this study. The subjects performed band-resisted parallel BSQ (accommodating elastic bands each sides of barbell) with five band conditions in random order. The duration of the deceleration subphase, mean mechanical power, and the force and velocity during the acceleration and deceleration subphases were calculated. BSQ with elastic bands elicited greater mechanical power output, velocity, and force during the deceleration subphase, in contrast to that elicited with traditional free weight (p < 0.05). BSQ with elastic bands also elicited greater mechanical power output and velocity during the acceleration subphase. However, the force output during the acceleration subphase using an elastic band was lesser than that using a traditional free weight (p < 0.05). This study suggests that BSQ with elastic band elicit greater power output during the acceleration and deceleration subphases.

Pinacidil-primed ATP-sensitive potassium channels mediate feedback control of mechanical power output in isolated myocardium of rats and guinea pigs

2010 ◽  
Vol 628 (1-3) ◽  
pp. 116-127 ◽  
Author(s):  
Diethart Schmid ◽  
Dawid L. Staudacher ◽  
Christian A. Plass ◽  
Hans G. Loew ◽  
Eva Fritz ◽  
...  
Keyword(s):  
Feedback Control ◽  
Potassium Channels ◽  
Power Output ◽  
Guinea Pigs ◽  
Mechanical Power ◽  
Mechanical Power Output ◽  
Isolated Myocardium

CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - ACTIVATION PATTERNS IN VIVO

1994 ◽  
Vol 187 (1) ◽  
pp. 261-274
Author(s):  
R Josephson ◽  
D Stokes
Keyword(s):  
Coefficient Of Variation ◽  
High Frequency ◽  
Interspike Interval ◽  
Carcinus Maenas ◽  
Single Muscle ◽  
Stroke Frequency ◽  
Activation Patterns ◽  
Animal Mass ◽  
Animal Size

1. The flagella of crustaceans are small appendages, borne on the maxillipeds, which beat repetitively when active. Flagellar movement is brought about by contraction of a single muscle, the flagellum abductor (FA). 2. The stroke frequency of the flagella of the green crab, Carcinus maenas, was about 11 Hz at 15 &deg;C and was relatively independent of animal size [frequency is proportional to (animal mass)-0.07], even though scaling considerations suggest that, for constant muscle stress, frequency should be proportional to mass-0.33. The coefficient of variation for intervals between successive strokes of a flagellum was about 4 %. 3. The FA is innervated by two excitatory motoneurones. Each of the neurones fired 0&shy;5 times during a stroke. The interspike interval when a neurone fired more than once during a stroke was 3&shy;4 ms.

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