Studien über Muskelwärme<sup>1</sup>

Blix, Magnus

doi:10.1111/j.1748-1716.1902.tb00501.x

Cited by 18 publications

(10 citation statements)

References 9 publications

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“…The modern era of using thermopiles to measure the heat production of isolated skeletal muscles began in earnest with the description by A. V. Hill of a thermopile, attributed to Blix (16), consisting of five copper-constantan thermocouples arranged in series (72). The device (Fig.…”

Section: Myometry Of Isolated Musclesmentioning

confidence: 99%

Muscle heat: a window into the thermodynamics of a molecular machine

Loiselle

Johnston

Han

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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contraction of muscle is characterized by the development of force and movement (mechanics) together with the generation of heat (metabolism). Heat represents that component of the enthalpy of ATP hydrolysis that is not captured by the microscopic machinery of the cell for the performance of work. It arises from two conceptually and temporally distinct sources: initial metabolism and recovery metabolism. Initial metabolism comprises the hydrolysis of ATP and its rapid regeneration by hydrolysis of phosphocreatine (PCr) in the processes underlying excitation-contraction coupling and subsequent cross-bridge cycling and sliding of the contractile filaments. Recovery metabolism describes those process, both aerobic (mitochondrial) and anaerobic (cytoplasmic), that produce ATP, thereby allowing the regeneration of PCr from its hydrolysis products. An equivalent partitioning of muscle heat production is often invoked by muscle physiologists. In this formulation, total enthalpy expenditure is separated into external mechanical work (W) and heat (Q). Heat is again partitioned into three conceptually distinct components: basal, activation, and force dependent. In the following mini-review, we trace the development of these ideas in parallel with the development of measurement techniques for separating the various thermal components.Microcalorimetry; muscle heat production; myothermy; thermopiles MUSCLE IS A MOLECULAR machine. It operates isothermally, isobarically, and isovolumetrically. At the microscopic level, it directly converts the Free Energy component of the enthalpy of ATP hydrolysis into cyclic attachment and detachment of actomyosin cross bridges, together with transportation of ions up their electrochemical potential gradients. At the macroscopic level, two consequences result: the generation of force and the evolution of heat. Of these two entities, heat is by far the more difficult to quantify and to interpret. In this brief review, we trace the development of techniques to measure muscle heat production from the mid-19th century to the present, providing parallel commentary on the progressive understanding of muscle function. We give particular consideration to the development of techniques of separating the metabolic cost of cross-bridge cycling from the purely "overhead" cost of its activation.

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Section: Myometry Of Isolated Musclesmentioning

confidence: 99%

Muscle heat: a window into the thermodynamics of a molecular machine

Loiselle

Johnston

Han

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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“…A substantial body of work was produced between the 1840s and 1910 by European scientists interested in heat production by animals in general and muscles in particular. This work was reviewed by Blix ( 1902 ). Three scientists in particular focussed on establishing whether less heat was produced in contractions in which work was performed than in an isometric contraction: Rudolph Heidenhain (Breslau, Germany), Adolph Fick (Wurzburg, Germany) and Magnus Blix (Lund, Sweden).…”

Section: Foundations Of Research On Muscle Energetics In the Nineteen...mentioning

confidence: 99%

A century of exercise physiology: key concepts in muscle energetics

Barclay

2022

Eur J Appl Physiol

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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.

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“…Finally the old results of Blix [ 31 ] should be mentioned, who always found the highest heat rate in the isometric stage, and that the muscle length promotes it too (“Länge macht Wärme”). It is possible that Blix with his simple thermo-galvanometer measured the heat which was later described as the “unexplained energy”: When an elongated muscle with little overlap is clamped, the thin filaments cannot drill after activation, since the muscle is clamped.…”

Section: The Underlying Mechanicsmentioning

confidence: 99%

The Different Muscle-Energetics during Shortening and Stretch

Jarosch

2011

IJMS

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The helical shape of the thin filaments causes their passive counterclockwise rotation during muscle stretch that increases tensile stress and torque at first by unwinding and then by winding up the four anchoring Z-filaments. This means storage of energy in the series elastic Z-filaments and a considerable decrease of the liberated energy of heat and work to (h—wap), where h is the heat energy and wap the stretch energy induced from outside by an apparatus. The steep thin filament helix with an inclination angle of 70° promotes the passive rotation during stretch, but impedes the smooth sliding of shortening by increased friction and production of frictional heat. The frictional heat may be produced by the contact with the myosin cross-bridges: (1) when they passively snap on drilling thin filaments from cleft to cleft over a distance 2 × 2.7 nm = 5.4 nm between the globular actin monomers in one groove, causing stepwise motion; or (2) when they passively cycle from one helical groove to the next (distance 36 nm). The latter causes more heat and may take place on rotating thin filaments without an effective forward drilling (“idle rotation”), e.g., when they produce “unexplained heat” at the beginning of an isometric tetanus. In an Appendix to this paper the different states of muscle are defined. The function of its most important components is described and rotation model and power-stroke model of muscular contraction is compared.

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Studien über Muskelwärme¹

Abstract: Einlcitnng.A l l g e m e i n e s .

Cited by 18 publications

References 9 publications

Muscle heat: a window into the thermodynamics of a molecular machine

Muscle heat: a window into the thermodynamics of a molecular machine

A century of exercise physiology: key concepts in muscle energetics

The Different Muscle-Energetics during Shortening and Stretch

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Studien über Muskelwärme1

Abstract: Einlcitnng.A l l g e m e i n e s .

Cited by 18 publications

References 9 publications

Muscle heat: a window into the thermodynamics of a molecular machine

Muscle heat: a window into the thermodynamics of a molecular machine

A century of exercise physiology: key concepts in muscle energetics

The Different Muscle-Energetics during Shortening and Stretch

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Product

Resources

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Studien über Muskelwärme¹