Cholesterol is a fat-like substance used to help build cell membranes, make certain hormones, synthesize vitamin D, and form bile secretions which facilitate digestion. Since fats cannot mix with water, which is the main ingredient of blood, cholesterol's most important function is to help transport fats through your blood vessels. Before cholesterol can enter the bloodstream, it is covered by a protein. These cholesterol-protein packages are called lipoproteins. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Lipoproteins are transport vehicles in circulating plasma that are composed of various lipids such as cholesterol, phospholipids, triglycerides, and proteins called apoproteins. The main classes of lipoproteins are chylomicrons, very low density lipoprotein cholesterol (VLDL-C), LDL-C, and HDL-C. Chylomicrons are the largest lipoproteins, consisting of approximately 85% triglycerides. Triglycerides are the main type of lipids found in adipose tissue and in the diet. Once the triglycerides are cleared from the chylomicron at receptor sites in the body, the remainder of the chylomicron is returned to the liver for further metabolism. The main lipid in VLDL-C is also triglycerides (60 to 70%). LDL-C is the main transporter of cholesterol in the circulation. About 50 to 60% of cholesterol is delivered to cells by LDL-C. Evidence suggests that LDL-C may contribute directly to cellular alterations in the inner walls of arteries, which may ultimately lead to the development of atherosclerotic plaque (Scann, 1978). Thus, LDL-C would be more strongly associated with coronary heart disease than total cholesterol (Manson et al., 1992). On the other hand, HDL-C has an inverse relationship with coronary heart disease, providing a protective mechanism against the development of CHD (Kannel, Castelli, & Gordon, 1971). HDL-C is considered the most powerful lipid parameter for predicting coronary heart disease in people of all ages (Gordon et al., 1977). The main function of HDL-C is to transport cholesterol from tissues and blood to the liver to be excreted from the body or synthesized into bile acids. HDL-C also prevents the absorption of LDL-C at receptor sites in the body and participates in the metabolism of other lipoproteins. HDL-C is primarily composed of phospholipids and is divided into several subclasses, based on particle size and density. The main subclasses are called HDL2 and HDL3. Women are known to have higher HDL2 content than men, which helps protect them against the development of coronary heart disease (Wood and Haskell, 1979). There are a variety of environmental and personal factors that can influence a person's cholesterol composition, such as age, gender, body fat level, dietary intake of fats, cholesterol and carbohydrates, alcohol consumption, smoking, medications, menopausal status and exercise. Due to the complex interactions between these variables, it is difficult to assess how each of these factors independently affects cholesterol levels and composition. Although total cholesterol levels are lower in people with high aerobic fitness than in people with low aerobic fitness, exercise training has not been conclusively shown to lower cholesterol.total. Measurements taken before and after exercise training have produced varying results with no clear consensus on whether or not moderate or vigorous exercise can reduce total cholesterol. In studies where total cholesterol was significantly reduced, it appears that activities were more dynamic and vigorous in nature, such as running. In contrast to the variable effects of exercise on total cholesterol, endurance exercise consistently reduces triglycerides (Martin, Haskell, & Wood, 1977). A physically active lifestyle can help prevent the age-related increase in triglycerides normally seen in men. It also appears that endurance exercise lowers triglyceride levels more in individuals with high initial baseline levels. Lower blood triglyceride concentrations have been attributed to increased lipoprotein lipase activity of skeletal muscle and adipose tissue resulting from aerobic training. Lipoprotein lipase is the key enzyme for the breakdown of triglyceride-rich lipoproteins. In the long term, the decrease in body fat that often accompanies endurance training may be a contributing factor to this exercise-induced decrease in triglycerides. As with total cholesterol, the impact of habitual aerobic exercise on LDL-C appears to be quite significant. variable. However, the majority of studies comparing endurance athletes to sedentary controls or the general population indicated that athletes had lower LDL-C levels, with leaner athletes often having the lowest values. Although it appears that endurance training may decrease LDL-C levels, there is little information on the biochemical mechanism behind this change. Endurance-trained athletes have much higher HDL-C values ​​than sedentary populations (Haskell, 1984). Although it is not yet definitive, moderate and high intensity aerobic training appears to be associated with elevated HDL-C values. The main reason for elevated HDL-C is an increase in lipoprotein lipase activity in response to exercise. Lipoprotein lipase accelerates the breakdown of triglycerides, resulting in transfer of cholesterol and other substances to HDL-C. Interestingly, healthy patients whose physical activity was limited to bed rest for three to six weeks due to some type of traumatic fracture showed a significant decrease in HDL-C levels (Nikkila, Kuusi and Myllynen, 1980). The term "lipid profile" describes the different levels of lipids in the blood, the most commonly reported being low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides. High levels of LDL cholesterol indicate excess lipids in the blood, which increases the risk of cardiovascular complications. HDL cholesterol transports lipids to the liver to be recycled and eliminated; therefore, high levels of HDL cholesterol are an indicator of a healthy cardiovascular system (Carroll MD, 2009). Plasma triglycerides come from fats consumed in food or other energy sources. Excess triglycerides in plasma are positively and independently associated with cardiovascular disease (da Luz P, 2008). Very low-density lipoprotein (VLDL) cholesterol, which is generally less frequently reported in the literature, has been shown to correlate positively with triglycerides and to be independently associated with cardiovascular risk, even in individuals who express normal LDL cholesterol levels (Ren J,2010). Perhaps the most commonly used measure of cholesterol is “total cholesterol,” a measure that includes LDL cholesterol and HDL cholesterol. However, given the different health effects of LDL cholesterol and HDL cholesterol, total cholesterol can be a misleading measure. More sensitive measures report, for example, total: HDL cholesterol levels or non-HDL cholesterol levels (i.e. all cholesterol variables that are positively associated with cardiovascular disease (Virani SS, 2012) ). There is a direct relationship between chronically high cholesterol levels (dyslipidemia) and coronary heart disease (CHD) (Lloyd-Jones DM, 2004). In a meta-analysis involving 170,000 participants (Baigent C, 2010), reducing LDL cholesterol was reported to decrease the incidence of heart attacks and ischemic strokes. It has also been reported that people with high total cholesterol levels ((200 mg/dL/5,172 mmol/L) have approximately twice the risk of coronary heart disease than those with optimal levels (180 mg/dL/5,172 mmol/L) 4.66 mmol/L) (Roger VL, 2010). The US Centers for Disease Control and Prevention has suggested that this is the case for 71 million American adults, which equates to 33.5% of adults. population (Centers for Disease Control and Prevention (CDC), 2011) The prevalence of high total cholesterol is even higher in Europe, where 54% of adults aged 25 and older have high total cholesterol. above recommended levels (World Health Organization, 2010) For more than 10 years, the link between high cholesterol and ischemic heart disease has been evident. Data from 2003 (Murray CJ, 2003) attributed a third of all. ischemic heart disease worldwide to high cholesterol levels While the age-adjusted prevalence of high cholesterol in the United States decreased from 26.6% (in 1988-1994) to 25.3% (in 1994-2004), recent data (Go AS, 2013) suggest that the proportion of the adult population using cholesterol-lowering pharmacological substances increased from 11.7 to 40.8% during this period. It has long been recognized that reducing serum cholesterol levels can reduce the risk of coronary heart disease. For example, a reduction of approximately 0.6 mmol/L can reduce the incidence of ischemic heart disease by 54% at age 40, and by 19% at age 80. (MR Law, 2012). A reduction in total cholesterol is therefore still considered the gold standard in preventive cardiovascular medicine (Whayne TF, 2011). This highlights the importance of interventions aimed at reducing serum cholesterol levels. Additionally, the benefit of early intervention has been demonstrated; long-term exposure to 1 mmol/L lower LDL cholesterol was associated with a 55% reduction in coronary heart disease risk, while statin therapy started later in life required a three-fold reduction. times LDL cholesterol to obtain the same magnitude of risk reduction (Ference BA, 2012). Pedersen and Saltin, citing 13 meta-analyses, reported improvements in lipid profile after exercise. They described this as Grade A evidence that exercise can have a positive effect on the pathogenesis, symptomatology and fitness of people with dyslipidemia. Additionally, Aadahl et al. reported a physical activity intervention based on lifestyle consultations in 1,693 sedentary men and women aged 33–64 years. Participants taking lipid-lowering medications were excluded from the analysis. At the 3-year follow-up, a significant positive association was observed between self-reported physical activity on24 hours and HDL cholesterol levels (p = 0.0001), while a significant negative association was observed. was reported between physical activity and triglyceride levels (p = 0.0001). Overall, the data suggest a dose-response relationship between increased physical activity and improvements in triglycerides and HDL cholesterol in previously sedentary populations. Five-year follow-up of a later study by Aadahl et al. reported significant associations between physical activity and improvements in total cholesterol (p = 0.006), LDL cholesterol (p = 0.007), triglycerides (p = 0.02), and HDL cholesterol (p = 0.006). 01) in 4,039 participants aged 30 to 60 years, although significant. Improvements in HDL cholesterol levels were only seen in men. Although the mechanisms underlying the effect of exercise on lipid profile are unclear, exercise appears to improve the ability of skeletal muscles to utilize lipids rather than glycogen, thereby reducing plasma lipid levels. (Earnest CP, 2013). Mechanisms may include an increase in lecithin-cholesterol acyltrans (LCAT) – the enzyme responsible for transferring esters to HDL cholesterol (Calabresi L, 2010), which has been shown to increase after exercise training (Riedl I , 2010) - and an increase in lipoproteins. lipase activity, although the data in this case are inconsistent (Harrison M, 2012) and may depend on the energy expenditure caused. Ferguson et al. reported that an energy expenditure of 1,100 kcal is required to cause an increase in HDL cholesterol that coincides with a significant increase in lipoprotein lipase activity. The process of removing cholesterol is known as “reverse cholesterol transport.” This process removes cholesterol from the circulation during elimination due to increased LCAT and reduced cholesteryl ester transfer protein (CETP) – the enzyme responsible for transferring HDL cholesterol to other lipoproteins – after acute and chronic exercise (Lira F, 2010). This increased enzymatic activity increases the ability of muscle fibers to oxidize fatty acids from plasma, VLDL cholesterol or triglycerides (Shaw I, 2009). This process is conceptualized by Kesaniemi et al. reviewed 51 articles describing physical activity interventions and reported an average increase in HDL cholesterol of 4.6%. The effects on LDL cholesterol and triglycerides have been reported to be inconsistent. The authors concluded that the most likely improvement in lipid profile induced by physical activity is an increase in HDL cholesterol. 2 Physical activity and types of exercise The terms “physical activity” and “exercise” are often used. The terms “physical activity” and “exercise” are often used interchangeably in the literature. However, it is suggested that the two terms denote two different concepts (U.S. Department of Health and Human Services, 1996). “Physical activity” refers to any bodily movement produced by skeletal muscles that results in energy expenditure (expressed in kilocalories) and includes a wide range of occupational, leisure, and daily activities. Rather, “Exercise” refers to planned or structured physical activity performed for a specific reason, which may be aerobic exercise, resistance training, or combined aerobic and resistance training. The above data to some extent support the proposition that physical activity and exercise can be used to improve cholesterol levels. It has been shown that physical activity.