Majid Koozehchian, M.S.
Childhood and adolescence are critical periods in the formation of cardiovascular risk factors. Many cardiovascular diseases are related to such risk factors as high levels of total cholesterol, low-density lipoprotein (LDL), and triglycerides (TG), as well as low levels of high-density lipoprotein (HDL). The causes of cardiovascular risk factors are manifold, involving environment, lifestyle, and genetics. In adolescents, higher levels of exercise training are inversely related to risk factor levels, suggesting the importance of developing an active life style early in life.
Often associated with these risk factors, cholesterol is a substance found in all animal products, as well as being produced by the body. Essential to the body, it is used to build cell membranes, produce sex hormones, and form bile acids, which are necessary for the digestion of fats. Research findings on the impact of physical activity in adolescence on cholesterol are mixed. Although plasma cholesterol level is largely unaffected by training or activity status, more active children or fit adolescents typically have lower levels.
Low-density lipoprotein (LDL) transports cholesterol to various body cells and deposits excess cholesterol in the artery walls, increasing the risk for heart disease. Elevated LDL is a major modifiable risk factor and has been associated with the early stages of atherosclerosis in adolescents. Increased LDL levels can be reduced by physical activity in children and adults.
Triglycerides (TG) are the chief form of fat in the diet and the major storage form of fat in the body, as well as providing calories to burn for energy. Many children and adolescents with higher TG levels also have other risk factors, such as high LDL or low HDL levels. Shulpis and Karikas found that increased TG levels were reduced by physical activity in adolescents.
High-density lipoprotein (HDL) transports cholesterol from blood and artery walls to the liver where it is converted to bile to be used for digestion or disposed of by the body; thus higher levels of HDL are desirable. This “reverse cholesterol transport process” helps prevent or reverse heart disease. Higher HDL levels have been consistently reported for more active, or fit, children and adolescents.
To improve cardiovascular health, the World Health Organization recommended at least 60 minutes of moderate intensity physical activity per day for children and youth aged 5-17. High intensity exercise should be included when possible.
The exercise prescription for children and adolescents should include aerobic exercise using large muscle groups. The exercise intensity should begin at low to moderate level, depending on the fitness level in children and adolescents. The improvement in blood lipid profile via exercise intervention during childhood or adolescence cannot be ignored.
Hasselstrom H, Hansen SE, Froberg K, Andersen LB. Physical fitness and physical activity during adolescence as predictors of cardiovascular disease risk in young adulthood. Danish Youth and Sports Study. An eight-year follow-up study Int J Sports Med 2002 May;23 Suppl 1:S27-31. https://www.thieme-connect.com/products/ejournals/html/10.1055/s-2002-28458
- Sternfeld B, Sidney S, Jacobs DR,Jr, Sadler MC, Haskell WL, Schreiner PJ. Seven-year changes in physical fitness, physical activity, and lipid profile in the CARDIA study. Coronary Artery Risk Development in Young Adults Ann Epidemiol 1999 Jan;9(1):25-33. http://ac.els-cdn.com/S1047279798000301/1-s2.0-S1047279798000301-main.pdf?_tid=c4c40aba-f6fd-11e3-a380-00000aacb35e&acdnat=1403105734_c592c4ffaf6caf96bf5a1370aecd854e
- Schulpis K, Karikas GA. Serum cholesterol and triglyceride distribution in 7767 school-aged Greek children Pediatrics 1998 May;101(5):861-864. http://pediatrics.aappublications.org/content/101/5/861.full.pdf+html
- Tolfrey K, Jones AM, Campbell IG. The effect of aerobic exercise training on the lipid-lipoprotein profile of children and adolescents Sports Med 2000 Feb;29(2):99-112. http://www.iub.edu/~k662/articles/lipid/children%20Tolfrey%202002.pdf