Mechanotransduction Mechanisms of Hypertrophy and Performance with Resistance Exercise
Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse in The Routledge Handbook on Biochemistry of Exercise, 2020
The ability of a single muscle fibre to produce force is largely dependent upon many of the structural proteins previously discussed. As mentioned earlier, the force-generating unit of the skeletal muscle is the sarcomere. The sarcomere can transmit force in two directions, laterally (perpendicular to the length of the muscle fibre, i.e., toward the plasma membrane) and longitudinally (parallel to the length of the muscle fibre toward the myotendinous junction). It has been demonstrated that ∼80% of force produced from a muscle fibre is transmitted in a lateral direction (142). This lateral force transmission is propagated from the sarcomere, through the cytoskeleton, across the costamere (i.e., integrins and other transmembrane proteins), to the ECM, and ultimately to the tendon to initiate movement. Consequently, modes of exercise which reinforce proteins within these lateral pathways, namely those most active during eccentric muscle actions, are proposed to improve muscle force production, transmission, and structural integrity.
The Fenn Effect: A Fundamental Mystery in Muscle
Haruo Sugi in Mysteries in Muscle Contraction, 2017
Although the isolation of single fibers from the muscle is technically difficult, the use of single fibers has the following advantages over the use of whole muscles: A single muscle fiber is a structural and functional unit of muscle at the cellular level and therefore free from all complications arising from whole muscle.Single muscle fibers, isolated successfully from whole muscle, survive for many hours to yield many reproducible results.Striation pattern (sarcomere spacing) of muscle fibers can be easily observed under a light microscope, so that changes in the sarcomere length can be recorded during experiments.
Exercise testing elite aerobic athletes
Robert B. Schoene, H. Thomas Robertson in Making Sense of Exercise Testing, 2018
There are two basic muscle fiber types, slow twitch (Type I) and fast twitch (Type II), the latter of which is further categorized as Type IIa and IIb. Whereas, the “twitch” term denotes literal contraction and function, the designations of Type I, Type IIa, and IIb convey important differences in fuel utilization and metabolic function. Type I fibers are mitochondrially dense and thus highly oxidative, utilizing largely free fatty acids (FFA) as a major fuel source; whereas, Type II fibers are glycogen rich, which, when activated, rely primarily on glucose metabolism and glycolysis for fuel and energy generation. Type II cells are the primary site of anaerobic metabolism during maximal effort. Type IIa fibers exhibit plasticity with training and can become more aerobic in their function.
Proteomic profiling of giant skeletal muscle proteins
Published in Expert Review of Proteomics, 2019
Sandra Murphy, Paul Dowling, Margit Zweyer, Dieter Swandulla, Kay Ohlendieck
As part of the systems biological characterisation of contractile fibres as one of the most abundant cell types in the human body [4], mass spectrometric profiling plays a key role in the establishment of the highly dynamic skeletal muscle proteome [5]. Although specialized to perform contractile work and integrate key pathways of energy metabolism, individual muscles exhibit substantial variations in their adaptability, multi-functionality, anatomical shape and fascicle organization. These functional and structural features of subtypes of skeletal muscles are echoed by their composition on the molecular, cellular and histological level [6]. In terms of categorising mammalian cell types, skeletal muscle fibres belong to an unusual class of multi-nucleated and very large cells that are exceedingly heterogeneous in their molecular composition of protein isoforms and highly adaptable to changed physiological demands [7]. In addition to their extraordinary length and specialised contractile properties, a striking biochemical property of skeletal muscle tissues is the prominent expression of giant protein species [8–10].
Morphological and functional changes in skeletal muscle in type 2 diabetes mellitus: A systematic review and meta-analysis
Published in Physiotherapy Theory and Practice, 2023
Jardeson Rocha Filgueiras, Cleudiane Pereira Sales, Ivanilson Gomes da Silva, Cristiana Maria Dos Santos, Elias de Carvalho Magalhães Neto, Rebeca Barbosa da Rocha, Vinicius Saura Cardoso
Four studies evaluated the composition of muscle fibers. Of these, three showed significantly different values between the T2DM and control groups (Gaster et al., 2001; Hickey et al., 1995; Mårin, Andersson, Krotkiewski, and Björntorp, 1994). Gaster et al. (2001) observed that the control had a significantly higher percentage of type I fibers in vastus lateralis muscle (51.3 ± 2.1%) than the obese groups without T2DM (43.9 ± 2.7%) and with T2DM (37.7 ± 4.9%). However, the control group had a significantly lower percentage of type II fibers (48.7 ± 2.1%) than the obese group without T2DM (56.1 ± 2.7%) and with T2DM (62.3 ± 4.9). Regarding the fiber diameter, there was no significant difference between groups. In a study by Andreassen et al. (2014) the number of blood capillaries by muscle fibers was lower in patients with T2DM than in controls (p = .63). However, no differences were found in the proportion of type I and II fibers in gastrocnemius muscle between the T2DM and control groups (p = .71).
Proteomic study of skeletal muscle in obesity and type 2 diabetes: progress and potential
Published in Expert Review of Proteomics, 2018
Human skeletal muscle biopsies are highly heterogenous and are often contaminated with other cell types such as adipocytes, neurons, and proteins originating from connective tissue, blood, and blood vessels. Besides contamination arising from other cells types and tissues, human skeletal muscle is usually composed of different fiber types, which contribute to the heterogeneity of the samples. Generally, adult human skeletal muscle fibers can be classified as either slow oxidative (type I), fast oxidative (type 2A), or fast glycolytic (type 2X) fibers [55]. The various muscle fiber types are metabolically different, which should be considered when performing studies of human skeletal muscle biopsies. The fiber type composition differs from one type of muscle to another [56] and it may be remodeled by hormonal and metabolic changes as well as by muscle activity [57]. Despite the metabolic differences between muscle fiber types and the different muscle fiber type compositions in various human muscles, most proteomic studies performed so far have utilized muscle biopsies from the vastus lateralis muscle [35–37,46,47,58–66], which is a mixed fiber muscle. However, since MS-based studies have revealed differences in the proteome of human vastus lateralis, trapezius, and deltoideus muscle [67,68], findings should be extended from one group of muscle to another with caution.
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