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.

Fast muscle function in the European eel (Anguilla anguillaL.) during aquatic and terrestrial locomotion

2001 ◽  
Vol 204 (13) ◽  
pp. 2231-2238 ◽  
Author(s):  
D. J. Ellerby ◽  
I. L. Y. Spierts ◽  
J. D. Altringham
Keyword(s):  
Muscle Activation ◽  
Muscle Power ◽  
The Body ◽  
Muscle Performance ◽  
Fast Muscle ◽  
Axial Position ◽  
European Eel ◽  
Cycle Frequency ◽  
Axial Location ◽  
Power Outputs

SUMMARYEels are capable of locomotion both in water and on land using undulations of the body axis. Axial undulations are powered by the lateral musculature. Differences in kinematics and the underlying patterns of fast muscle activation are apparent between locomotion in these two environments. The change in isometric fast muscle properties with axial location was less marked than in most other species. Time from stimulus to peak force (Ta) did not change significantly with axial position and was 82±6ms at 0.45BL and 93±3ms at 0.75BL, where BL is total body length. Time from stimulus to 90% relaxation (T90) changed significantly with axial location, increasing from 203±11ms at 0.45BL to 239±9ms at 0.75BL. Fast muscle power outputs were measured using the work loop technique. Maximum power outputs at ±5% strain using optimal stimuli were 17.3±1.3Wkg−1 in muscle from 0.45BL and 16.3±1.5Wkg−1 in muscle from 0.75BL. Power output peaked at a cycle frequency of 2Hz. The stimulus patterns associated with swimming generated greater force and power than those associated with terrestrial crawling. This decrease in muscle performance in eels may occur because on land the eel is constrained to a particular kinematic pattern in order to produce thrust against an underlying substratum.

scholarly journals Maturational changes in troponin T expression, Ca2+-sensitivity and twitch contraction kinetics in dragonfly flight muscle

1997 ◽  
Vol 200 (10) ◽  
pp. 1473-1482 ◽  
Author(s):  
G Fitzhugh ◽  
J Marden
Keyword(s):  
Muscle Activation ◽  
Flight Muscle ◽  
Developmental Change ◽  
Troponin T ◽  
Thermal Sensitivity ◽  
Regulatory Protein ◽  
Shortening Velocity ◽  
Twitch Contraction ◽  
Age Related ◽  
Contraction Kinetics

Maximum lift production and the thermal sensitivity of lift production increase dramatically during adult maturation of Libellula pulchella dragonflies. Here, we report that the mechanistic basis for this transition appears to involve a developmental change in protein expression, which alters the Ca2+-sensitivity of muscle activation and twitch contraction kinetics. The alternatively spliced Ca2+ regulatory protein troponin T (TnT) undergoes an isoform shift during adult maturation. Skinned (demembranated) fibers of mature flight muscle are up to 13 times more sensitive to activation by Ca2+ than skinned fibers from teneral (newly emerged adult) flight muscle, and their Ca2+-sensitivity is more strongly affected by temperature. Intact muscle from mature individuals has a shorter time to peak tension and longer time to half-relaxation during twitch contractions, which is consistent with a greater Ca2+-sensitivity of mature muscle. Because it becomes activated more quickly and relaxes more slowly, mature flight muscle is able to generate, with each twitch, more force per unit area than teneral muscle; this difference in force becomes greater at high temperatures. There do not appear to be any age-related differences in actomyosin crossbridge properties, since teneral and mature flight muscles do not differ in shortening velocity, tetanic tension or instantaneous power output during isotonic contraction. Thus, variation in TnT expression appears to affect the temperature-dependent Ca2+-sensitivity of muscle activation, which in turn affects the kinetics and force production of the twitch contractions used by dragonflies during flight. This cascade of effects suggests that maturational changes in the expression of TnT isoforms may be a key determinant of overall muscle and organismal performance.

scholarly journals Determinants of metabolic cost during submaximal cycling

2002 ◽  
Vol 93 (3) ◽  
pp. 823-828 ◽  
Author(s):  
J. McDaniel ◽  
J. L. Durstine ◽  
G. A. Hand ◽  
J. C. Martin
Keyword(s):  
Power Output ◽  
Muscle Activation ◽  
Metabolic Cost ◽  
Mechanical Power ◽  
Shortening Velocity ◽  
Mechanical Power Output ◽  
Muscle Shortening ◽  
Main Determinants ◽  
Power Outputs ◽  
Pedaling Rate

The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost ( R 2 = 0.99 ± 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 ± 7 metabolic watts and 22.1 ± 0.3% (145-mm cranks, 40 rpm) to a high of 297 ± 23 metabolic watts and 26.6 ± 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.

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.

scholarly journals The Aerob and Anaerob Performance Beta-Alanine Supplement and Ergogenic Aid Using to the Power Output Variables in Cyclists: A Cohort Studies Random Model Effect

2021 ◽  
Author(s):  
Yeliz Kahraman
Keyword(s):  
Cohort Studies ◽  
Power Output ◽  
Muscle Power ◽  
Aerobic Power ◽  
Anaerobic Power ◽  
The Body ◽  
Muscle Performance ◽  
P Value ◽  
Value Analysis ◽  
Beta Alanine

: Supplement the use of ergogenic aids in cyclist’s directly have been improved the body metabolism and hemodynamic factors that are micro supplement in chancing reactions on the body muscle mass and limb muscle. Mostly knowing that, muscle power development progressive fast glycolytic and short time oxidative systems reactions. Sport competition intervals, therefore, during periods has been used specific drinks supported to cyclists. But, be obtained during should be long race times. Athletes directly needed some drug and fluid intake to prevented from metabolic breakdown rapidly the dynamic physiologic performance factors. Beta-alanine supplementation can be direct muscle performance development affects the anaerobic metabolism and capacity. It should be de-termined how the cyclists will use the competitive and training period intervals can increase the cyclists specific sprint and endurance race performance. Science cyclist International Road doses will be created in which, intervals can random effectively the investigate. This study random a cohort studies is examined the effects of beta-alanine supplementation on aerobic and anaerobic power output in specific cyclists. Therefore, we have been databases PubMed, Scopus and Medline initial search 10 August 2020 were created prospective effect the quality of bias work concluded effect size (ES) 95% confidence interval (CI) were used in participant. Participations (N=66) have age range 25 to 38 of the using beta-alanine in training periods to endurance muscle performance, aerobic power, anaerobic power, and sprint time trials. As a result of beta-alanine improved an-aerobic and aerobic power output on 4-week time-dependent trial performance condition. Signifi-cant values are obtained level factor alpha <0.05 and p-value analysis pre-post interactive stand-ardization.

The mechanical power output of the pectoralis muscle of blue-breasted quail (Coturnix chinensis): thein vivolength cycle and its implications for muscle performance

2001 ◽  
Vol 204 (21) ◽  
pp. 3587-3600 ◽  
Author(s):  
Graham N. Askew ◽  
Richard L. Marsh
Keyword(s):  
Power Output ◽  
Muscle Performance ◽  
Emg Activity ◽  
Pectoralis Muscle ◽  
Shortening Velocity ◽  
Mechanical Power Output ◽  
Strain Trajectory ◽  
The Mean ◽  
Net Power Output

SUMMARYSonomicrometry and electromyographic (EMG) recordings were made for the pectoralis muscle of blue-breasted quail (Coturnix chinensis) during take-off and horizontal flight. In both modes of flight, the pectoralis strain trajectory was asymmetrical, with 70 % of the total cycle time spent shortening. EMG activity was found to start just before mid-upstroke and continued into the downstroke. The wingbeat frequency was 23 Hz, and the total strain was 23 % of the mean resting length.Bundles of fibres were dissected from the pectoralis and subjected in vitro to the in vivo length and activity patterns, whilst measuring force. The net power output was only 80 W kg–1 because of a large artefact in the force record during lengthening. For more realistic estimates of the pectoralis power output, we ignored the power absorbed by the muscle bundles during lengthening. The net power output during shortening averaged over the entire cycle was approximately 350 W kg–1, and in several preparations over 400 W kg–1. Sawtooth cycles were also examined for comparison with the simulation cycles, which were identical in all respects apart from the velocity profile. The power output during these cycles was found to be 14 % lower than during the in vivo strain trajectory. This difference was due to a higher velocity of stretch, which resulted in greater activation and higher power output throughout the later part of shortening, and the increase in shortening velocity towards the end of shortening, which facilitated deactivation.The muscle was found to operate at a mean length shorter than the plateau of the length/force relationship, which resulted in the isometric stress measured at the mean resting length being lower than is typically reported for striated muscle.

Force-Velocity Relationships of a Locust Flight Muscle at Different Times During a Twitch Contraction

1991 ◽  
Vol 159 (1) ◽  
pp. 65-87 ◽  
Author(s):  
JEAN G. MALAMUD ◽  
ROBERT K. JOSEPHSON
Keyword(s):  
Flight Muscle ◽  
Isometric Force ◽  
Velocity Curve ◽  
Shortening Velocity ◽  
Single Twitch ◽  
Emory University ◽  
Generating Capacity ◽  
Force Velocity ◽  
Maximum Isometric Force ◽  
Isometric Twitch

The force-velocity relationships during isotonic shortening were determined for the metathoracic second tergocoxal muscle of the locust Schistocerca americana (Drury). This muscle is a synchronous flight muscle. During the plateau of a tetanic contraction, the maximum shortening velocity (Vmax) determined from the force-velocity curve was 5.2 muscle lengths s−1 (25°C) and the curvature (a/Po) was 0.62. The maximum isometric force (P0) was 36.3 N cm−2. Early in a twitch (at times shorter than the isometric twitch rise time) the values for Vmax and curvature were similar to those during the tetanic plateau, but the curves at different times during the twitch intercepted the force axis at values less than P0. Later in the twitch, Vmax declined. A variable termed degree of activation (DA) is developed as a measure of the force-generating capacity of a muscle when this may be time-varying, as throughout most of a twitch. DA is determined from the shortening velocity at an intermediate load and is the predicted intercept of the force-velocity curve with the force axis relative to the tetanic intercept. In the locust muscle, DA rose to a maximum in 2–3 ms after the end of the latent period. DA reached 80° of the tetanic value during a single twitch; during the second twitch of a pair, the peak DA reached approximately the tetanic value. After a brief plateau, DA declined approximately exponentially. The time constant of DA decay was about 14 ms. Note: Present address: Department of Physiology, Emory University, Atlanta, GA30322, USA.

MYOTOMAL MUSCLE FUNCTION AT DIFFERENT LOCATIONS IN THE BODY OF A SWIMMING FISH

1993 ◽  
Vol 182 (1) ◽  
pp. 191-206 ◽  
Author(s):  
J. D. Altringham ◽  
C. S. Wardle ◽  
C. I. Smith
Keyword(s):  
Power Output ◽  
Muscle Function ◽  
Muscle Activation ◽  
Muscle Power ◽  
Travelling Waves ◽  
The Body ◽  
Muscle Fibres ◽  
Cycle Frequency ◽  
Lateral Muscle

We describe experiments on isolated, live muscle fibres which simulate their in vivo activity in a swimming saithe (Pollachius virens). Superficial fast muscle fibres isolated from points 0.35, 0.5 and 0.65 body lengths (BL) from the anterior tip had different contractile properties. Twitch contraction time increased from rostral to caudal myotomes and power output (measured by the work loop technique) decreased. Power versus cycle frequency curves of rostral fibres were shifted to higher frequencies relative to those of caudal fibres. In the fish, phase differences between caudally travelling waves of muscle activation and fish bending suggest a change in muscle function along the body. In vitro experiments indicate that in vivo superficial fast fibres of rostral myotomes are operating under conditions that yield maximum power output. Caudal myotomes are active as they are lengthened in vivo and initially operate under conditions which maximise their stiffness, before entering a positive power-generating phase. A description is presented for the generation of thrust at the tail blade by the superficial, fast, lateral muscle. Power generated rostrally is transmitted to the tail by stiffened muscle placed more caudally. A transition zone between power generation and stiffening travels caudally, and all but the most caudal myotomes generate power at some phase of the tailbeat. Rostral power output, caudal force, bending moment and force at the tail blade are all maximal at essentially the same moment in the tailbeat cycle, as the tail blade crosses the swimming track.

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.

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