scholarly journals Modulation of flight muscle power output in budgerigars Melopsittacus undulatus and zebra finches Taeniopygia guttata: in vitro muscle performance

2007 ◽  
Vol 210 (21) ◽  
pp. 3780-3788 ◽  
Author(s):  
D. J. Ellerby ◽  
G. N. Askew
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Flight Muscle ◽  
Taeniopygia Guttata ◽  
Muscle Performance ◽  
Melopsittacus Undulatus ◽  
Zebra Finches ◽  
Muscle Power Output

scholarly journals Flight muscle power increases with strain amplitude and decreases with cycle frequency in zebra finches (Taeniopygia guttata)

2020 ◽  
Vol 223 (21) ◽  
pp. jeb225839 ◽  
Author(s):  
Joseph W. Bahlman ◽  
Vikram B. Baliga ◽  
Douglas L. Altshuler
Keyword(s):  
Strain Amplitude ◽  
Power Output ◽  
Muscle Power ◽  
Aerodynamic Force ◽  
Taeniopygia Guttata ◽  
Zebra Finches ◽  
Kinematic Parameters ◽  
Wingbeat Frequency ◽  
Cycle Frequency ◽  
Stroke Amplitude

ABSTRACTBirds that use high flapping frequencies can modulate aerodynamic force by varying wing velocity, which is primarily a function of stroke amplitude and wingbeat frequency. Previous measurements from zebra finches (Taeniopygia guttata) flying across a range of speeds in a wind tunnel demonstrate that although the birds modulated both wingbeat kinematic parameters, they exhibited greater changes in stroke amplitude. These two kinematic parameters contribute equally to aerodynamic force, so the preference for modulating amplitude over frequency may instead derive from limitations of muscle physiology at high frequency. We tested this hypothesis by developing a novel in situ work loop approach to measure muscle force and power output from the whole pectoralis major of zebra finches. This method allowed for multiple measurements over several hours without significant degradation in muscle power. We explored the parameter space of stimulus, strain amplitude and cycle frequencies measured previously from zebra finches, which revealed overall high net power output of the muscle, despite substantial levels of counter-productive power during muscle lengthening. We directly compared how changes to muscle shortening velocity via strain amplitude and cycle frequency affected muscle power. Increases in strain amplitude led to increased power output during shortening with little to no change in power output during lengthening. In contrast, increases in cycle frequency did not lead to increased power during shortening but instead increased counter-productive power during lengthening. These results demonstrate why at high wingbeat frequency, increasing wing stroke amplitude could be a more effective mechanism to cope with increased aerodynamic demands.

Effects of caffeine on mouse skeletal muscle power output during recovery from fatigue

2004 ◽  
Vol 96 (2) ◽  
pp. 545-552 ◽  
Author(s):  
Rob. S. James ◽  
Robbie S. Wilson ◽  
Graham N. Askew
Keyword(s):  
Skeletal Muscle ◽  
Power Output ◽  
Muscle Power ◽  
Plasma Concentrations ◽  
Muscle Stiffness ◽  
Muscle Performance ◽  
Work Output ◽  
Work Input ◽  
Net Power Output

The effects of 10 mM (high) and 70 μM (physiologically relevant) caffeine on force, work output, and power output of isolated mouse extensor digitorum longus (EDL) and soleus muscles were investigated in vitro during recovery from fatigue at 35°C. To monitor muscle performance during recovery from fatigue, we regularly subjected the muscle to a series of cyclical work loops. Force, work, and power output during shortening were significantly higher after treatment with 10 mM caffeine, probably as a result of increased Ca2+ release from the sarcoplasmic reticulum. However, the work required to relengthen the muscle also increased in the presence of 10 mM caffeine. This was due to a slowing of relaxation and an increase in muscle stiffness. The combination of increased work output during shortening and increased work input during lengthening had different effects on the two muscles. Net power output of mouse soleus muscle decreased as a result of 10 mM caffeine exposure, whereas net power output of the EDL muscle showed a transient, significant increase. Treatment with 70 μM caffeine had no significant effect on force, work, or power output of EDL or soleus muscles, suggesting that the plasma concentrations found when caffeine is used to enhance performance in human athletes might not directly affect the contractile performance of fatigued skeletal muscle.

scholarly journals The influence of temperature on power production during swimming. II. Mechanics of red muscle fibres in vivo

2000 ◽  
Vol 203 (2) ◽  
pp. 333-345 ◽  
Author(s):  
L.C. Rome ◽  
D.M. Swank ◽  
D.J. Coughlin
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Muscle Performance ◽  
Muscle Fibres ◽  
Relaxation Rates ◽  
Red Muscle ◽  
The Impact ◽  
Positive Work ◽  
Muscle Power Output

We found previously that scup (Stenotomus chrysops) reduce neither their stimulation duration nor their tail-beat frequency to compensate for the slow relaxation rates of their muscles at low swimming temperatures. To assess the impact of this ‘lack of compensation’ on power generation during swimming, we drove red muscle bundles under their in vivo conditions and measured the resulting power output. Although these in vivo conditions were near the optimal conditions for much of the muscle at 20 degrees C, they were far from optimal at 10 degrees C. Accordingly, in vivo power output was extremely low at 10 degrees C. Although at 30 cm s(−)(1), muscles from all regions of the fish generated positive work, at 40 and 50 cm s(−)(1), only the POST region (70 % total length) generated positive work, and that level was low. This led to a Q(10) of 4–14 in the POST region (depending on swimming speed), and extremely high or indeterminate Q(10) values (if power at 10 degrees C is zero or negative, Q(10) is indeterminate) for the other regions while swimming at 40 or 50 cm s(−)(1). To assess whether errors in measurement of the in vivo conditions could cause artificially reduced power measurements at 10 degrees C, we drove muscle bundles through a series of conditions in which the stimulation duration was shortened and other parameters were made closer to optimal. This sensitivity analysis revealed that the low power output could not be explained by realistic levels of systematic or random error. By integrating the muscle power output over the fish's mass and comparing it with power requirements for swimming, we conclude that, although the fish could swim at 30 cm s(−)(1) with the red muscle alone, it is very unlikely that it could do so at 40 and 50 cm s(−)(1), thus raising the question of how the fish powers swimming at these speeds. By integrating in vivo pink muscle power output along the length of the fish, we obtained the surprising finding that, at 50 cm s(−)(1), the pink muscle (despite having one-third the mass) contributes six times more power to swimming than does the red muscle. Thus, in scup, pink muscle is crucial for powering swimming at low temperatures. This overall analysis shows that Q(10) values determined in experiments on isolated tissue under arbitrarily selected conditions can be very different from Q(10) values in vivo, and therefore that predicting whole-animal performance from these isolated tissue experiments may lead to qualitatively incorrect conclusions. To make a meaningful assessment of the effects of temperature on muscle and locomotory performance, muscle performance must be studied under the conditions at which the muscle operates in vivo.

scholarly journals Evolutionary adaptation of contractile performance in muscle of ectothermic winter-flying moths

1995 ◽  
Vol 198 (10) ◽  
pp. 2087-2094 ◽  
Author(s):  
J Marden
Keyword(s):  
Power Output ◽  
Muscle Activation ◽  
Muscle Power ◽  
Flight Muscle ◽  
Thermal Sensitivity ◽  
Muscle Performance ◽  
Shortening Velocity ◽  
Instantaneous Power ◽  
Generating Capacity ◽  
Power Outputs

The temperature-sensitivity of muscle performance in a winter-flying ecotothermic moth (Operophtera bruceata) was examined and compared with that of a summer-flying endothermic hawkmoth (Manduca sexta). O. bruceata muscle contracted over a temperature range of 1­28 °C, whereas M. sexta muscle contracted at temperatures of 13­42.5 °C. Maximum (unloaded) contraction velocity (Vmax) was greater in O. bruceata over most of the range of temperatures where muscle from both species was excitable (3­4 lengths s-1 versus 0.6­3.6 lengths s-1 at 13­28 °C), but M. sexta muscle achieved a much higher Vmax at the temperature that this species maintains during flight (10 lengths s-1 at 40­42.5 °C). The capacity of O. bruceata muscle to generate tension was approximately twice that of M. sexta muscle (peak tetanic tension of 13.9 versus 7.0 N cm-2). This greater force-generating capacity in O. bruceata largely offset its lower shortening velocity, such that maximum instantaneous power output was equivalent in both species at temperatures below 35 °C (approximately 100­120 W kg-1). M. sexta muscle achieved instantaneous power outputs of up to 202 W kg-1 at temperatures of 40­42.5 °C. Muscle activation and deactivation (measured by times to peak tension and to half-relaxation during isometric twitches) were most rapid for O. bruceata at temperatures of 15­30 °C and for M. sexta at temperatures of 30­40 °C. Data for power output of flight muscle from these moths are combined with estimates of induced power required for flight in order to show how adaptations for thermal sensitivity of muscle power output interact with morphology (low wing-loading, high flight muscle ratio) to allow O. bruceata moths to fly at extremely low body temperatures, and to construct a model showing how the fecundity of flightless O. bruceata females would decline if they were to regain the ability to fly. Marginal flight over a narrow range of temperatures for O. bruceata females would require a 17 % reduction in fecundity; to fly over as large a range of temperatures as do males would require an 82 % reduction in fecundity.

scholarly journals Does a physiological concentration of taurine increase acute muscle power output, time to fatigue, and recovery in isolated mouse soleus (slow) muscle with or without the presence of caffeine?

2014 ◽  
Vol 92 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Jason Tallis ◽  
Matthew F. Higgins ◽  
Val. M. Cox ◽  
Michael J. Duncan ◽  
Rob. S. James
Keyword(s):  
Power Output ◽  
Muscle Power ◽  
Muscle Performance ◽  
Human Consumption ◽  
High Concentration ◽  
Taurine Supplementation ◽  
Physiological Concentration ◽  
Significant Difference ◽  
High Concentrations ◽  
Muscle Power Output

High concentrations of caffeine and taurine are key constituents of many ergogenic supplements ingested acutely to provide legal enhancements in athlete performance. Despite this, there is little evidence supporting the claims for the performance-enhancing effects of acute taurine supplementation. In-vitro models have demonstrated that a caffeine-induced muscle contracture can be further potentiated when combined with a high concentration of taurine. However, the high concentrations of caffeine used in previous research would be toxic for human consumption. Therefore, this study aimed to investigate whether a physiological dose of caffeine and taurine would directly potentiate skeletal muscle performance. Isolated mouse soleus muscle was used to examine the effects of physiological taurine (TAU), caffeine (CAF), and taurine–caffeine combined (TC) on (i) acute muscle power output; (ii) time to fatigue; and (iii) recovery from fatigue, compared with the untreated controls (CON). Treatment with TAU failed to elicit any significant difference in the measured parameters. Treatment with TC resulted in a significant increase in acute muscle power output and faster time to fatigue. The ergogenic benefit posed by TC was not different from the effects of caffeine alone, suggesting no acute ergogenic benefit of taurine.

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

Role of muscle power output as a mediator between gait variability and gait velocity in hospitalized older adults

2019 ◽  
Vol 124 ◽  
pp. 110631 ◽  
Author(s):  
Mikel L. Sáez de Asteasu ◽  
Nicolás Martínez-Velilla ◽  
Fabricio Zambom-Ferraresi ◽  
Álvaro Casas-Herrero ◽  
Robinson Ramirez-Vélez ◽  
...  
Keyword(s):  
Older Adults ◽  
Power Output ◽  
Muscle Power ◽  
Gait Variability ◽  
Gait Velocity ◽  
Hospitalized Older Adults ◽  
Muscle Power Output
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