Effects of Exercise on Gene Enhancement

Introduction

The effects of physical activity on mental and physical well-being are well known. Regular physical activity reduces the risk of several chronic medical conditions, such as depression, cardiovascular disease, diabetes, obesity, cancer, etc. Many social, behavioral, environmental, psychological, and biological factors are involved in physical activity. Most human behavioral traits are attributed to the environment and genetic factors. Still, the current understanding of genetic architecture attributing to physical activity is very limited compared to other factors like genetic diseases.

How Physical Inactivity Can Influence Gene Expression?

Physical inactivity can lead to failure in maintaining homeostatic signaling of gene expression at the paleolithic level. Since the genes that require physical activity are also susceptible to disease, a decrease in physical activity can inhibit the health-promoting proteins and activate the disease-promoting proteins. This can further lead to alterations in intracellular homeostasis and exceed the threshold of physiological significance. This manifests the pathophysiologic state of overt clinical symptoms like hyperglycemia (high blood sugar level), dyspnea (shortness of breath), hyperinsulinemia (high levels of insulin in the blood), angina (chest pain), and exercise intolerance and thereby diminishes survival.

What Is the Functioning of Exercise Responsive Gene in Exercise Deficiency?

Physical activity shapes the human genotype and phenotype. Phenotypic changes associated with exercise deficiency include a decrease in size and strength of skeletal muscle, low capacity of skeletal muscle to oxidize carbohydrates and fats, high insulin resistance, high homeostatic disruption of cellular metabolism in skeletal muscle at a given absolute workload, less vasodilator capacity in the perfusion vessels of the heart, smaller maximal cardiac outputs and stroke volumes, and sarcopenia. The phenotype associated with exercise deficiency shows that thresholds of biological significance have been surpassed by altered gene expression, so overt clinical conditions can occur. For example, a deficiency in the caloric expenditure of only 450 kilojoules a day from walking more than 21 minutes a day to not walking at all is associated with an increase in the prevalence of mortality and many other chronic health conditions like diabetes and cancer.

What Are the Studies Conducted for Heritability of Physical Activity?

There were various studies conducted worldwide to determine the degree of heritability of physical activity among people; some of the studies are mentioned below-

1. Family Studies- Family studies have shown that genetic factors contribute to variation in physical activity, with heritability estimates ranging from 9 percent to 57 percent. These studies suggested that heritability was greater when physical activity was assessed with accelerometers. There were no sex-specific differences or differences in maternal-to-offspring versus paternal-to-offspring correlations found.

2. Twin Studies- The heritability of physical activity between male and female pairs was almost similar.

3. Genome-wide Linkage Studies- Substantial linkage of variation in exercise participation was measured on chromosome 19p13.3. This region has several genes related to muscle performance and blood flow, which may indirectly affect exercise participation. Other chromosomes were 3q22-q24 and 4q31-q34.

4. Candidate Genes - The association between dopamine neurotransmission and physical activity has been widely studied. A strong correlation was suggested between individuals carrying the dopamine D4 receptor 7R allele and increased physical activity levels.

5. Genome -Wide Association Studies (GWAS)- All the GWAS conducted to date have identified significant loci. Still, none of them was replicated between studies, and only one of the GWAS has used accelerometry. GWAS was conducted to locate the potentially causal single nucleotide polymorphism (SNPs) involved in the phenotype.

What Are the Effects of Different Exercises on Telomeres?

Telomeres are evolutionary conserved deoxyribonucleic acid (DNA) found at the ends of eukaryotic chromosomes. Telomeres are responsible for preserving genetic information and guarding against genomic instability. However, with natural aging, telomeric DNA is lost with each round of cell division until critical length, at which cellular senescence ensues. Given the myriad of lifestyle and environmental factors associated with short telomeres, telomere length is considered a cellular marker of health status and biological aging. Different modes of exercise can affect the telomeres and increase an individual's health status and lifespan.

Acute exercise can modulate gene expression by epigenetic alterations and lead to potential health benefits. Several health benefits achieved through regulating genes, mainly controlling muscle structure and function, can be triggered by acute exercise. Endurance training can acutely increase telomerase activity. An immediate increase in telomeres after an acute aerobic exercise session was found and similar effects in response to acute exercise that might contribute to maintaining telomeres have been reported.

How Exercises Change the Gene Expression in Organ Systems?

Endurance exercise training remodels the activity of gene enhancers in skeletal muscle. Studies have been conducted on young individuals to monitor the changes in skeletal muscle after endurance training. It was discovered that after completing the endurance training, the structure of many enhancers in the skeletal muscle of these individuals had been altered. By connecting the enhancers to genetic databases, it was discovered that many of the regulated enhancers have already been identified as hotspots of genetic variation between these individuals. Scientists found that exercise can benefit organs distant from muscle, like the brain. These benefits result from the signals released by the muscles into the bloodstream.

Exercise can remodel enhancer activity in skeletal muscle linked to cognitive abilities, which opens for identifying exercise training-induced secreted muscle factors targeted to the brain. Studies also report that exercising can produce a unique cardiac phenotype with increased physiological and clinical function. Exercise can also increase the uptake of glucose in the skeletal muscle.

Conclusion

With various studies and research conducted taken into account, it has been concluded that exercising benefits not only the physiological and psychological status of an individual but also enhances the gene expression responsible for affecting different organ systems of the human body. The lack of amount of physical activity can lead to alterations in gene expression and contribute to mortality and morbidity, which also emphasizes the importance of the evolutionary pressures that have shaped the human physiological responses to better understand the functions of exercise-induced changes in gene expression, both in physiological and pathophysiological conditions. Hence, it is important to incorporate mild to moderate daily exercises.