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Faster triceps surae muscle cyclic contractions alter muscle activity and whole body metabolic rate.Journal of Applied Physiology... Feb 2023Hundred years ago, Fenn demonstrated that when a muscle shortens faster, its energy liberation increases. Fenn's results were the first of many that led to the general...
Hundred years ago, Fenn demonstrated that when a muscle shortens faster, its energy liberation increases. Fenn's results were the first of many that led to the general understanding that isometric muscle contractions are energetically cheaper than concentric contractions. However, this evidence is still primarily based on single fiber or isolated (ex vivo) muscle studies and it remains unknown whether this translates to whole body metabolic rate. In this study, we specifically changed the contraction velocity of the ankle plantar flexors and quantified the effects on triceps surae muscle activity and whole body metabolic rate during cyclic plantar flexion (PF) contractions. Fifteen participants performed submaximal ankle plantar flexions (∼1/3 s activation and ∼2/3 s relaxation) on a dynamometer at three different ankle angular velocities: isometric (10° PF), isokinetic at 30°/s (5-15° PF), and isokinetic at 60°/s (0-20° PF) while target torque (25% MVC) and cycle frequency were kept constant. In addition, to directly determine the effect of ankle angular velocity on muscle kinematics we collected gastrocnemius medialis muscle fascicle ultrasound data. As expected, increasing ankle angular velocity increased gastrocnemius medialis muscle fascicle contraction velocity and positive mechanical work ( < 0.01), increased mean and peak triceps surae muscle activity ( < 0.01), and considerably increased net whole body metabolic rate ( < 0.01). Interestingly, the increase in triceps surae muscle activity with fast ankle angular velocities was most pronounced in the gastrocnemius lateralis ( < 0.05). Overall, our results support the original findings from Fenn in 1923 and we demonstrated that greater triceps surae muscle contraction velocities translate to increased whole body metabolic rate. Single muscle fiber studies or research on isolated (ex vivo) muscles demonstrated that faster concentric muscle contractions yield increased energy consumption. Here we translated this knowledge to muscle activation and whole body metabolic rate. Increasing ankle angular velocity increased triceps surae contraction velocity and mechanical work, increasing triceps surae muscle activity and substantially elevating whole body metabolic rate. Additionally, we demonstrated that triceps surae muscle activation strategy depends on the mechanical demands of the task.
Topics: Humans; Muscle, Skeletal; Muscle Contraction; Isometric Contraction; Leg; Ankle Joint
PubMed: 36603047
DOI: 10.1152/japplphysiol.00575.2022 -
The Journal of Physiology Apr 2023Skeletal muscle is the most abundant component of the mature mammalian phenotype. Designed to generate contractile force and movement, skeletal muscle is crucial for... (Review)
Review
Skeletal muscle is the most abundant component of the mature mammalian phenotype. Designed to generate contractile force and movement, skeletal muscle is crucial for organism health, function and development. One of the great interests for muscle biologists is in understanding how skeletal muscle adapts during periods of stress and stimuli, such as disease, disuse and ageing. To this end, genomic-based experimental and analytical approaches offer one of the most powerful approaches for comprehensively mapping the molecular paradigms that regulate skeletal muscle. With the power, applicability, and robustness of 'omic' technologies continually being developed, we are now in a position to investigate these molecular mechanisms in skeletal muscle to an unprecedented level of accuracy and precision, heralding the dawn of a new era of functional genomics in the field of muscle physiology.
Topics: Animals; Genomics; Muscle, Skeletal; Muscle Contraction; Aging; Phenotype; Mammals
PubMed: 36829294
DOI: 10.1113/JP284206 -
Journal of the Royal Society, Interface Sep 2021While skeletal muscle mass has been shown to decrease mass-specific mechanical work per cycle, it is not yet known how muscle mass alters contraction efficiency. In this...
While skeletal muscle mass has been shown to decrease mass-specific mechanical work per cycle, it is not yet known how muscle mass alters contraction efficiency. In this study, we examined the effect of muscle mass on mass-specific metabolic cost and efficiency during cyclic contractions in simulated muscles of different sizes. We additionally explored how tendon and its stiffness alters the effects of muscle mass on mass-specific work, mass-specific metabolic cost and efficiency across different muscle sizes. To examine contraction efficiency, we estimated the metabolic cost of the cycles using established cost models. We found that for motor contractions in which the muscle was primarily active during shortening, greater muscle mass resulted in lower contraction efficiency, primarily due to lower mass-specific mechanical work per cycle. The addition of a tendon in series with the mass-enhanced muscle model improved the mass-specific work and efficiency per cycle with greater mass for motor contractions, particularly with a shorter excitation duty cycle, despite higher predicted metabolic cost. The results of this study indicate that muscle mass is an important determinant of whole muscle contraction efficiency.
Topics: Biomechanical Phenomena; Elasticity; Isometric Contraction; Muscle Contraction; Muscle, Skeletal; Tendons
PubMed: 34583567
DOI: 10.1098/rsif.2021.0484 -
Anasthesiologie, Intensivmedizin,... Oct 2016
Topics: Brain; Consciousness Monitors; Electroencephalography; Electromyography; Humans; Muscle Contraction; Neuromuscular Blockade; Neuromuscular Monitoring; Neuromuscular Nondepolarizing Agents; Reference Values; Wakefulness
PubMed: 27764861
DOI: 10.1055/s-0042-115510 -
Journal of Applied Physiology... May 2024
Topics: Humans; Muscle Contraction; Muscle, Skeletal; Biomechanical Phenomena
PubMed: 38743397
DOI: 10.1152/japplphysiol.00204.2024 -
Journal of Applied Physiology... May 2024
Topics: Humans; Muscle, Skeletal; Muscle Contraction; Biomechanical Phenomena
PubMed: 38299220
DOI: 10.1152/japplphysiol.00860.2023 -
Advances in Physiology Education Dec 2019Lewis Victor Heilbrunn has been called the pioneer of Ca as an intracellular regulator (Campbell AK. 7: 287-296, 1986; Campbell AK. , 2015). In 1947, he was the first...
Lewis Victor Heilbrunn has been called the pioneer of Ca as an intracellular regulator (Campbell AK. 7: 287-296, 1986; Campbell AK. , 2015). In 1947, he was the first to provide convincing evidence that Ca triggered muscle contraction (Heilbrunn LV, Wiercinski FJ. 29: 15-32, 1947). Yet his work was met mostly with silence and neglect. One wonders why. Heilbrunn was a general physiologist who believed in the uniformity of nature with regard to movement. He believed that ". . . the theory of what makes cells divide should not be very different from the theory of what makes muscle contract . . ." (Heilbrunn LV. , 1956). He did not believe that one could understand how the living machine worked by investigating its parts. He believed that, to understand life, one must study the dynamics of living protoplasm. The origin and evolution of Heilbrunn's thought process regarding the role of Ca as a physiological activator will be traced back to the 1920s. The ways in which he tested the Ca hypothesis in sea urchin eggs in the 1920s and 1930s will be explored. This work shaped Heilbrunn's thinking about the role of Ca in muscle contraction. Importantly, why he and his results were ignored for years will be examined. It turned out that being right was not enough. Bad luck and a stubborn belief in an outmoded scientific philosophy contributed to the neglect.
Topics: Calcium; History, 19th Century; History, 20th Century; Humans; Male; Medical Laboratory Personnel; Muscle Contraction; Physiology
PubMed: 31553642
DOI: 10.1152/advan.00094.2019 -
Sports Medicine (Auckland, N.Z.) Dec 2016Runners at various levels of performance and specializing in different events (from 800 m to marathons) wear compression socks, sleeves, shorts, and/or tights in... (Review)
Review
BACKGROUND
Runners at various levels of performance and specializing in different events (from 800 m to marathons) wear compression socks, sleeves, shorts, and/or tights in attempt to improve their performance and facilitate recovery. Recently, a number of publications reporting contradictory results with regard to the influence of compression garments in this context have appeared.
OBJECTIVES
To assess original research on the effects of compression clothing (socks, calf sleeves, shorts, and tights) on running performance and recovery.
METHOD
A computerized research of the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science was performed in September of 2015, and the relevant articles published in peer-reviewed journals were thus identified rated using the Physiotherapy Evidence Database (PEDro) Scale. Studies examining effects on physiological, psychological, and/or biomechanical parameters during or after running were included, and means and measures of variability for the outcome employed to calculate Hedges'g effect size and associated 95 % confidence intervals for comparison of experimental (compression) and control (non-compression) trials.
RESULTS
Compression garments exerted no statistically significant mean effects on running performance (times for a (half) marathon, 15-km trail running, 5- and 10-km runs, and 400-m sprint), maximal and submaximal oxygen uptake, blood lactate concentrations, blood gas kinetics, cardiac parameters (including heart rate, cardiac output, cardiac index, and stroke volume), body and perceived temperature, or the performance of strength-related tasks after running. Small positive effect sizes were calculated for the time to exhaustion (in incremental or step tests), running economy (including biomechanical variables), clearance of blood lactate, perceived exertion, maximal voluntary isometric contraction and peak leg muscle power immediately after running, and markers of muscle damage and inflammation. The body core temperature was moderately affected by compression, while the effect size values for post-exercise leg soreness and the delay in onset of muscle fatigue indicated large positive effects.
CONCLUSION
Our present findings suggest that by wearing compression clothing, runners may improve variables related to endurance performance (i.e., time to exhaustion) slightly, due to improvements in running economy, biomechanical variables, perception, and muscle temperature. They should also benefit from reduced muscle pain, damage, and inflammation.
Topics: Athletic Performance; Clothing; Exercise Test; Humans; Isometric Contraction; Movement; Muscle Contraction; Muscle Fatigue; Running
PubMed: 27106555
DOI: 10.1007/s40279-016-0546-5 -
International Journal of Molecular... Mar 2023Findings from experiments that used hydrostatic pressure changes to analyse the process of skeletal muscle contraction are re-examined. The force in resting muscle is... (Review)
Review
Findings from experiments that used hydrostatic pressure changes to analyse the process of skeletal muscle contraction are re-examined. The force in resting muscle is insensitive to an increase in hydrostatic pressure from 0.1 MPa (atmospheric) to 10 MPa, as also found for force in rubber-like elastic filaments. The force in rigour muscle rises with increased pressure, as shown experimentally for normal elastic fibres (e.g., glass, collagen, keratin, etc.). In submaximal active contractions, high pressure leads to tension potentiation. The force in maximally activated muscle decreases with increased pressure: the extent of this force decrease in maximal active muscle is sensitive to the concentration of products of ATP hydrolysis (Pi-inorganic phosphate and ADP-adenosine diphosphate) in the medium. When the increased hydrostatic pressure is rapidly decreased, the force recovered to the atmospheric level in all cases. Thus, the resting muscle force remained the same: the force in the rigour muscle decreased in one phase and that in active muscle increased in two phases. The rate of rise of active force on rapid pressure release increased with the concentration of Pi in the medium, indicating that it is coupled to the Pi release step in the ATPase-driven crossbridge cycle in muscle. Pressure experiments on intact muscle illustrate possible underlying mechanisms of tension potentiation and causes of muscle fatigue.
Topics: Hydrostatic Pressure; Muscles; Muscle Contraction; Muscle Fatigue; Adenosine Triphosphatases; Isometric Contraction; Adenosine Triphosphate
PubMed: 36902460
DOI: 10.3390/ijms24055031 -
European Journal of Applied Physiology Jan 2023In the mid-nineteenth century, the concept of muscle behaving like a stretched spring was developed. This elastic model of contraction predicted that the energy... (Review)
Review
In the mid-nineteenth century, the concept of muscle behaving like a stretched spring was developed. This elastic model of contraction predicted that the energy available to perform work was established at the start of a contraction. Despite several studies showing evidence inconsistent with the elastic model, it persisted into the twentieth century. In 1923, W. O. Fenn published a paper in which he presented evidence that appeared to clearly refute the elastic model. Fenn showed that when a muscle performs work it produces more heat than when contracting isometrically. He proposed that energy for performing work was only made available in a muscle as and when that work was performed. However, his ideas were not adopted and it was only after 15 years of technical developments that in 1938 A. V. Hill performed experiments that conclusively disproved the elastic model and supported Fenn's conclusions. Hill showed that the rate of heat production increased as a muscle made the transition from isometric to working contraction. Understanding the basis of the phenomenon observed by Fenn and Hill required another 40 years in which the processes that generate force and work in muscle and the associated scheme of biochemical reactions were established. Demonstration of the biochemical equivalent of Hill's observations-changes in rate of ATP splitting when performing work-in 1999 was possible through further technical advances. The concept that the energy, from ATP splitting, required to perform work is dynamically modulated in accord with the loads a muscle encounters when contracting is key to understanding muscle energetics.
Topics: Male; Humans; Muscle Contraction; Muscles; Adenosine Triphosphate
PubMed: 36271943
DOI: 10.1007/s00421-022-05070-7