Endurance

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Twins Tashi and Nungshi Malik on endurance trek at the foothills of the Himalayas Endurance training for Mt Carstensz Pyramid.JPG
Twins Tashi and Nungshi Malik on endurance trek at the foothills of the Himalayas

Endurance (also related to sufferance, forbearance, resilience, constitution, fortitude, persistence, tenacity, steadfastness, perseverance, stamina, and hardiness) is the ability of an organism to exert itself and remain active for a long period of time, as well as its ability to resist, withstand, recover from and have immunity to trauma, wounds, or fatigue.

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The term is often used in the context of aerobic or anaerobic exercise. The definition of "long" varies according to the type of exertion – minutes for high intensity anaerobic exercise, hours or days for low intensity aerobic exercise. Training for endurance can reduce endurance strength [ verification needed ] [1] unless an individual also undertakes resistance training to counteract this effect.

When a person is able to accomplish or withstand more effort than previously, their endurance is increasing. To improve their endurance they may slowly increase the amount of repetitions or time spent; in some exercises, more repetitions taken rapidly improve muscle strength but have less effect on endurance. [2] Increasing endurance has been proven to release endorphins resulting in a positive mind.[ citation needed ] The act of gaining endurance through physical activity decreases anxiety, depression, and stress, or any chronic disease [ dubious discuss ]. [3] Although a greater endurance can assist the cardiovascular system this does not imply that endurance is guaranteed to improve any cardiovascular disease. [4] "The major metabolic consequences of the adaptations of muscle to endurance exercise are a slower utilization of muscle glycogen and blood glucose, a greater reliance on fat oxidation, and less lactate production during exercise of a given intensity." [5]

The term stamina is sometimes used synonymously and interchangeably with endurance. Endurance may also refer to an ability to persevere through a difficult situation, to "endure hardship".

In military settings, endurance is the ability of a force[ clarification needed ] to sustain high levels of combat potential relative to its opponent over the duration of a campaign. [6]

Philosophy

Aristotle noted similarities between endurance and self control: To have self control is to resist the temptation of things that seem immediately appealing, while to endure is to resist the discouragement of things that seem immediately uncomfortable. [7]

Endurance training

Different types of endurance performance can be trained in specific ways. Adaptation of exercise plans should follow individual goals.

Calculating the intensity of exercise the individual capabilities should be considered[ by whom? ]. Effective training starts within half the individual performance capability.[ further explanation needed ] Performance capability is expressed by maximum heart rate. Best[ clarification needed ] results can be achieved in the range between 55% and 65% of maximum heart rate. Aerobic, anaerobic and further thresholds are not to be mentioned within extensive endurance exercises.[ why? ] Training intensity is measured via the heart rate. [8]

Endurance-trained effects are mediated by epigenetic mechanisms

Between 2012 and 2019 at least 25 reports indicated a major role of epigenetic mechanisms in skeletal muscle responses to exercise. [9]

Regulation of transcription in mammals
An active enhancer regulatory region is enabled to interact with the promoter region of its target gene by formation of a chromosome loop. This can allow initiation of messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one architectural protein anchored to the enhancer and one anchored to the promoter, and these proteins are joined together to form a dimer (red zigzags). Specific regulatory transcription factors bind to DNA sequence motifs on the enhancer. General transcription factors bind to the promoter. When a transcription factor is activated by a signal (here indicated as phosphorylation shown by a small red star on a transcription factor on the enhancer) the enhancer is activated and can now activate its target promoter. The active enhancer is transcribed on each strand of DNA in opposite directions by bound RNAP IIs. Mediator (a complex consisting of about 26 proteins in an interacting structure) communicates regulatory signals from the enhancer DNA-bound transcription factors to the promoter. Regulation of transcription in mammals.jpg
Regulation of transcription in mammals
An active enhancer regulatory region is enabled to interact with the promoter region of its target gene by formation of a chromosome loop. This can allow initiation of messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one architectural protein anchored to the enhancer and one anchored to the promoter, and these proteins are joined together to form a dimer (red zigzags). Specific regulatory transcription factors bind to DNA sequence motifs on the enhancer. General transcription factors bind to the promoter. When a transcription factor is activated by a signal (here indicated as phosphorylation shown by a small red star on a transcription factor on the enhancer) the enhancer is activated and can now activate its target promoter. The active enhancer is transcribed on each strand of DNA in opposite directions by bound RNAP IIs. Mediator (a complex consisting of about 26 proteins in an interacting structure) communicates regulatory signals from the enhancer DNA-bound transcription factors to the promoter.

Gene expression in muscle is largely regulated, as in tissues generally, by regulatory DNA sequences, especially enhancers. Enhancers are non-coding sequences in the genome that activate the expression of distant target genes, [10] by looping around and interacting with the promoters of their target genes [11] (see Figure "Regulation of transcription in mammals"). As reported by Williams et al., [12] the average distance in the loop between the connected enhancers and promoters of genes is 239,000 nucleotide bases.

Endurance exercise-induced long-term alteration of gene expression by histone acetylation or deacetylation

A nucleosome with histone tails set for transcriptional activation
DNA in the nucleus generally consists of segments of 146 base pairs of DNA wrapped around nucleosomes connected to adjacent nucleosomes by linker DNA. Nucleosomes consist of four pairs of histone proteins in a tightly assembled core region plus up to 30% of each histone remaining in a loosely organized polypeptide tail (only one tail of each pair is shown). The pairs of histones, H2A, H2B, H3 and H4, each have lysines (K) in their tails, some of which are subject to post-translational modifications consisting, usually, of acetylations [Ac] and methylations {me}. The lysines (K) are designated with a number showing their position as, for instance, (K4), indicating lysine as the 4th amino acid from the amino (N) end of the tail in the histone protein. The particular acetylations [Ac] and methylations {Me} shown are those that occur on nucleosomes close to, or at, some DNA regions undergoing transcriptional activation of the DNA wrapped around the nucleosome. Histone tails set for transcriptional activation.jpg
A nucleosome with histone tails set for transcriptional activation
DNA in the nucleus generally consists of segments of 146 base pairs of DNA wrapped around nucleosomes connected to adjacent nucleosomes by linker DNA. Nucleosomes consist of four pairs of histone proteins in a tightly assembled core region plus up to 30% of each histone remaining in a loosely organized polypeptide tail (only one tail of each pair is shown). The pairs of histones, H2A, H2B, H3 and H4, each have lysines (K) in their tails, some of which are subject to post-translational modifications consisting, usually, of acetylations [Ac] and methylations {me}. The lysines (K) are designated with a number showing their position as, for instance, (K4), indicating lysine as the 4th amino acid from the amino (N) end of the tail in the histone protein. The particular acetylations [Ac] and methylations {Me} shown are those that occur on nucleosomes close to, or at, some DNA regions undergoing transcriptional activation of the DNA wrapped around the nucleosome.

After exercise, epigenetic alterations to enhancers alter long-term expression of hundreds of muscle genes. This includes genes producing proteins and other products secreted into the systemic circulation, many of which may act as endocrine messengers. [12] Of 817 genes with altered expression, 157 (according to Uniprot) or 392 (according to Exocarta) of the proteins produced according to those genes were known to be secreted from the muscles. Four days after an endurance type of exercise, many genes have persistently altered epigentically regulated expression. [12] Four pathways altered were in the platelet/coagulation system, the cognitive system, the cardiovascular system, and the renal system. Epigenetic regulation of these genes was indicated by epigenetic alterations in the distant upstream DNA regulatory sequences of the enhancers of these genes.

Up-regulated genes had epigenetic acetylations added at histone 3 lysine 27 (H3k27ac) of nucleosomes located at the enhancers controlling those up-regulated genes, while down-regulated genes had epigenetic acetylations removed from H3K27 in nucleosomes located at the enhancers that control those genes (see Figure "A nucleosome with histone tails set for transcriptional activation"). Biopsies of the vastus lateralis muscle showed expression of 13,108 genes at baseline before an exercise training program. Six sedentary 23-year-old Caucasian males provided vastus lateralis biopsies before entering an exercise program (six weeks of 60-minute sessions of riding a stationary cycle, five days per week). Four days after the exercise program was completed, biopsies of the same muscles had altered gene expression, with 641 genes up-regulated and 176 genes down-regulated. Williams et al. [12] identified 599 enhancer-gene interactions, covering 491 enhancers and 268 genes, where both the enhancer and the connected target gene were coordinately either upregulated or downregulated after exercise training.

Endurance exercise-induced alteration to gene expression by DNA methylation or demethylation

Endurance muscle training also alters muscle gene expression through epigenetic DNA methylation or de-methylation of CpG sites within enhancers. [13] In a study by Lindholm et al., [13] twenty-three 27-year-old, sedentary, male and female volunteers had endurance training on only one leg during three months. The other leg was used as an untrained control leg. Skeletal muscle biopsies from the vastus lateralis were taken both before training began and 24 hours after the last training session from each of the legs. The endurance-trained leg, compared to the untrained leg, had significant DNA methylation changes at 4,919 sites across the genome. The sites of altered DNA methylation were predominantly in enhancers. Transcriptional analysis, using RNA sequencing, identified 4,076 differentially expressed genes.

The transcriptionally upregulated genes were associated with enhancers that had a significant decrease in DNA methylation, while transcriptionally downregulated genes were associated with enhancers that had increased DNA methylation. In this study, the differentially methylated positions in enhancers with increased methylation were mainly associated with genes involved in structural remodeling of the muscle and glucose metabolism. The differentially decreased methylated positions in enhancers were associated with genes functioning in inflammatory/immunological processes and transcriptional regulation.

See also

Related Research Articles

<span class="mw-page-title-main">Epigenetics</span> Study of DNA modifications that do not change its sequence

In biology, epigenetics is the study of heritable traits, or a stable change of cell function, that happen without changes to the DNA sequence. The Greek prefix epi- in epigenetics implies features that are "on top of" or "in addition to" the traditional genetic mechanism of inheritance. Epigenetics usually involves a change that is not erased by cell division, and affects the regulation of gene expression. Such effects on cellular and physiological phenotypic traits may result from environmental factors, or be part of normal development. Epigenetic factors can also lead to cancer.

<span class="mw-page-title-main">Euchromatin</span> Lightly packed form of chromatin that is enriched in genes

Euchromatin is a lightly packed form of chromatin that is enriched in genes, and is often under active transcription. Euchromatin stands in contrast to heterochromatin, which is tightly packed and less accessible for transcription. 92% of the human genome is euchromatic.

<span class="mw-page-title-main">Cellular differentiation</span> Transformation of a stem cell to a more specialized cell

Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover. Some differentiation occurs in response to antigen exposure. Differentiation dramatically changes a cell's size, shape, membrane potential, metabolic activity, and responsiveness to signals. These changes are largely due to highly controlled modifications in gene expression and are the study of epigenetics. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. Metabolic composition, however, gets dramatically altered where stem cells are characterized by abundant metabolites with highly unsaturated structures whose levels decrease upon differentiation. Thus, different cells can have very different physical characteristics despite having the same genome.

A regulatory sequence is a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism. Regulation of gene expression is an essential feature of all living organisms and viruses.

<span class="mw-page-title-main">Skeletal muscle</span> One of three major types of muscle

Skeletal muscle is one of the three types of vertebrate muscle tissue, the other being cardiac muscle and smooth muscle. They are part of the voluntary muscular system and typically are attached by tendons to bones of a skeleton. The skeletal muscle cells are much longer than in the other types of muscle tissue, and are also known as muscle fibers. The tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres.

<span class="mw-page-title-main">Regulation of gene expression</span> Modifying mechanisms used by cells to increase or decrease the production of specific gene products

Regulation of gene expression, or gene regulation, includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific gene products. Sophisticated programs of gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from transcriptional initiation, to RNA processing, and to the post-translational modification of a protein. Often, one gene regulator controls another, and so on, in a gene regulatory network.

<span class="mw-page-title-main">Epigenome</span> Biological term

In biology, the epigenome of an organism is the collection of chemical changes to its DNA and histone proteins that affects when, where, and how the DNA is expressed; these changes can be passed down to an organism's offspring via transgenerational epigenetic inheritance. Changes to the epigenome can result in changes to the structure of chromatin and changes to the function of the genome. The human epigenome, including DNA methylation and histone modification, is maintained through cell division. The epigenome is essential for normal development and cellular differentiation, enabling cells with the same genetic code to perform different functions. The human epigenome is dynamic and can be influenced by environmental factors such as diet, stress, and toxins.

Histone methylation is a process by which methyl groups are transferred to amino acids of histone proteins that make up nucleosomes, which the DNA double helix wraps around to form chromosomes. Methylation of histones can either increase or decrease transcription of genes, depending on which amino acids in the histones are methylated, and how many methyl groups are attached. Methylation events that weaken chemical attractions between histone tails and DNA increase transcription because they enable the DNA to uncoil from nucleosomes so that transcription factor proteins and RNA polymerase can access the DNA. This process is critical for the regulation of gene expression that allows different cells to express different genes.

<span class="mw-page-title-main">CTCF</span> Transcription factor

Transcriptional repressor CTCF also known as 11-zinc finger protein or CCCTC-binding factor is a transcription factor that in humans is encoded by the CTCF gene. CTCF is involved in many cellular processes, including transcriptional regulation, insulator activity, V(D)J recombination and regulation of chromatin architecture.

Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression. Such remodeling is principally carried out by 1) covalent histone modifications by specific enzymes, e.g., histone acetyltransferases (HATs), deacetylases, methyltransferases, and kinases, and 2) ATP-dependent chromatin remodeling complexes which either move, eject or restructure nucleosomes. Besides actively regulating gene expression, dynamic remodeling of chromatin imparts an epigenetic regulatory role in several key biological processes, egg cells DNA replication and repair; apoptosis; chromosome segregation as well as development and pluripotency. Aberrations in chromatin remodeling proteins are found to be associated with human diseases, including cancer. Targeting chromatin remodeling pathways is currently evolving as a major therapeutic strategy in the treatment of several cancers.

Epigenomics is the study of the complete set of epigenetic modifications on the genetic material of a cell, known as the epigenome. The field is analogous to genomics and proteomics, which are the study of the genome and proteome of a cell. Epigenetic modifications are reversible modifications on a cell's DNA or histones that affect gene expression without altering the DNA sequence. Epigenomic maintenance is a continuous process and plays an important role in stability of eukaryotic genomes by taking part in crucial biological mechanisms like DNA repair. Plant flavones are said to be inhibiting epigenomic marks that cause cancers. Two of the most characterized epigenetic modifications are DNA methylation and histone modification. Epigenetic modifications play an important role in gene expression and regulation, and are involved in numerous cellular processes such as in differentiation/development and tumorigenesis. The study of epigenetics on a global level has been made possible only recently through the adaptation of genomic high-throughput assays.

<span class="mw-page-title-main">EHMT1</span> Protein-coding gene in the species Homo sapiens

Euchromatic histone-lysine N-methyltransferase 1, also known as G9a-like protein (GLP), is a protein that in humans is encoded by the EHMT1 gene.

While the cellular and molecular mechanisms of learning and memory have long been a central focus of neuroscience, it is only in recent years that attention has turned to the epigenetic mechanisms behind the dynamic changes in gene transcription responsible for memory formation and maintenance. Epigenetic gene regulation often involves the physical marking of DNA or associated proteins to cause or allow long-lasting changes in gene activity. Epigenetic mechanisms such as DNA methylation and histone modifications have been shown to play an important role in learning and memory.

In recent years it has become apparent that the environment and underlying mechanisms affect gene expression and the genome outside of the central dogma of biology. It has been found that many epigenetic mechanisms are involved in the regulation and expression of genes such as DNA methylation and chromatin remodeling. These epigenetic mechanisms are believed to be a contributing factor to pathological diseases such as type 2 diabetes. An understanding of the epigenome of diabetes patients may help to elucidate otherwise hidden causes of this disease.

Epigenetic regulation of neurogenesis is the role that epigenetics plays in the regulation of neurogenesis.

<span class="mw-page-title-main">Epigenetic therapy</span> Use of epigenome-influencing techniques to treat medical conditions

Epigenetic therapy refers to the use of drugs or other interventions to modify gene expression patterns, potentially treating diseases by targeting epigenetic mechanisms such as DNA methylation and histone modifications.

Epigenetics of physical exercise is the study of epigenetic modifications to the cell genome resulting from physical exercise. Environmental factors, including physical exercise, have been shown to have a beneficial influence on epigenetic modifications. Generally, it has been shown that acute and long-term exercise has a significant effect on DNA methylation, an important aspect of epigenetic modifications.

H3K4me3 is an epigenetic modification to the DNA packaging protein Histone H3 that indicates tri-methylation at the 4th lysine residue of the histone H3 protein and is often involved in the regulation of gene expression. The name denotes the addition of three methyl groups (trimethylation) to the lysine 4 on the histone H3 protein.

Pharmacoepigenetics is an emerging field that studies the underlying epigenetic marking patterns that lead to variation in an individual's response to medical treatment.

Epigenetics of autoimmune disorders is the role that epigenetics play in autoimmune diseases. Autoimmune disorders are a diverse class of diseases that share a common origin. These diseases originate when the immune system becomes dysregulated and mistakenly attacks healthy tissue rather than foreign invaders. These diseases are classified as either local or systemic based upon whether they affect a single body system or if they cause systemic damage.

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