Monday, February 23, 2009


Exercise - makes you sound in mind and body

Ancient man had to physically exert himself to survive. What is now considered a form of physical exercise - walking was their only mode of transportation. Thus physical exercise was a part of one’s existence. This may explain why the Veddah community has been shown to be devoid of diseases such as diabetes and hypertension (high blood pressure). An editorial in a local newspaper has drawn attention to the lack of physical activity among the population contributing to the epidemic of obesity and diabetes (DN 9/2/09) and the social cost of this change in life style.


Dr. A.S. Dissanayake former Professor of Physiology, Medical Faculty, Ragama

Physical activity is among the life style factors that have important and independent effects on health, others being diet, smoking, and alcohol use.

Physical activity is any bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above basal levels (standing, walking slowly and lifting light weight objects as a part of one’s daily life).

Health-enhancing physical activities include:

Aerobic activities include brisk walking, jogging, swimming, cycling, jumping rope and dancing.

Exercise - a part of one’s daily life

Muscle strengthening activities - lifting weights, children climbing on playground equipment.

Bone-strengthening activities - Running, basketball, tennis, jumping rope and hopscotch. Bone-strengthening activities can also be aerobic and muscle-strengthening.

Physical activity affects many health conditions, and the specific amounts and types of activity that benefit each condition vary. Additional benefits occur with more physical activity. Benefits occur across the board for children and adolescents, young and middle-aged adults, older adults, and those in every studied racial and ethnic group and even for those with disabilities including mental disabilities.

The health benefits on bodily functions include:

In children and adolescents

Improved cardio respiratory and muscular fitness

Improved cardiovascular and metabolic health biomarkers - rise in HDL or ‘good’ cholesterol and fall in LDL or ‘bad’ cholesterol, better blood sugar control are some.

Improved bone health and bone mass - Bone-strengthening activities commonly produced by impact with the ground promotes bone growth and strength.

Reducing body fat
Youth who are regularly active also have a better chance of a healthy adulthood.

In adults and older adults, there is strong evidence to suggest that exercise:

reduces risk of early death - people who engage in the amount of exercise recommended below live an average of three to seven years longer.

reduces coronary heart disease, stroke and high blood pressure - effect are observed on virtually all risk factors of cardiovascular disease.

Exercise causes the heart muscle tp contract forcefully and frequently, increasing blood flow through the arteries leading to subtle changes in the autonomic nervous system, which controls the contraction and relaxation of these vessels.

This fine-tuning leads to a lower, lower blood pressure and a more variable heart rate thus reducing the risk of cardiovascular disease. Exercise also reduces inflammation associated with atherosclerosis which contributes to heart attacks.

improves the blood lipid profile - by decreasing the amount of plasma triglycerides - fatty molecules in the blood that are associated with plaque build-up in the arteries. Physical activity helps reduce the particle size of low-density lipoprotein (LDL) in the blood, and increase amounts of high-density lipoprotein (HDL).

improves cardio-respiratory and muscular fitness.

may prevent and even reverse type 2 diabetes. In type 2 diabetes the body begins to ignore or fails to produce enough insulin (insulin resistance) causing a build up of fat leading to biochemical reactions that interfere with the activity of insulin. Muscle activity increases the beak down of fats reducing this action.

helps reduce abdominal fat - decreasing the risk of metabolic syndrome a precursor of type 2 diabetes and coronary heart disease, said to occur in commonly in South Asians.

prevents weight gain and induces weight loss, particularly when combined with reduced calorie intake. Exercising may encourage people to crave healthier unrefined foods (like fiber-rich cereals, lentils, leafy vegetables etc.).

reduces risk of some cancers. Regular exercise lowers the risk particularly for breast and colon cancer. Such effects are probably the outcome of complex and subtle changes in hormone levels (insulin, oestrogen and progesterone among them) and in the activity of the immune system following regular exercise.

may also increase bone density, lower risk of hip fracture and improve sleep.

The effects of exercise on the brain are less easily appreciated. Most associate athleticism with lower academic performance. However, evidence is accumulating to show that exercise has direct effects on the brain.

In children, exercise:
reduces likelihood of them developing symptoms of anxiety and mental depression

improves cognitive function - regular exercise in children appears to improve brain function - cognition in particular. Some do not agree that there is a clear cut effect but allowing sufficient time in the school curriculum for daily exercise has been definitely shown not to impair academic performance.

In adults there is very good evidence to show that exercise:

makes you smarter - It seems to do so by increasing brain blood flow and the production of certain brain growth promoting molecules called neurotrophins within specific areas of the brain such as the hippocampus an area associated with what is called ‘executive control function’.

reduces depression - there is evidence to suggest that exercise helps in treatment of depressive illness.

reduces the risk for Alzheimer’s disease and makes for better functional health in older adults.

One may ask as to whether there are no adverse effects of exercise. Many think that exercise increases the risk of sudden death from heart attacks or incurring bodily injury. The benefits of exercise far outweigh the risks.

Exercise guidelines:
Inactive individuals should have themselves checked out by their doctor prior to commencing an exercise regime.

How much exercise and how frequently?

The guidelines issued recently by the U.S. Department of Health and Social Security are:

For adults walking is a good way to get aerobic physical activity. Walking has many health benefits and a low risk of injury. It can be done year-round and in many settings.

The accumulated time spent has a greater impact on the health status than frequency.

To reduce risk of injury, start slowly and increase the amount of physical activity gradually over a period of weeks to months. For example, an inactive person could start with a walking program consisting of 5 minutes of slow walking several times each day, 5 to 6 days a week.

The length of time could then gradually be increased to 10 minutes per session, 3 times a day, and the walking speed could be increased slowly. In the long term one should aim at doing about 150 minutes of accumulated exercise per week.

The good news is that “some is better than none”, some health benefits are seen even when one does as little as 60 minutes a week of aerobic exercise.

Adults should also do muscle-strengthening activities (lifting light weights) that are moderate or high intensity and involve all major muscle groups on 2 or more days a week.

Children and adolescents should do 60 minutes (1 hour) or more of physical activity daily.

Most of this should be in the form of aerobic activities done at least 3 times a week and of moderate to vigorous intensity.

Muscle strengthening and bone strengthening activities should also be included. Bone-strengthening activities remain especially important for children and young adolescents because the greatest gains in bone mass occur during the years just before and during puberty. It is important to encourage young people to participate in physical activities that are appropriate for their age, enjoyable, and that offer variety.

Time has to be found for both structured and unstructured physical activity during school and outside of school.

In our state schools, 80 minutes (2 periods a week) are set aside for physical education from Grade 6 through 9 and is optional for Grades 10 and 11. In addition those in Grade 6 and upwards are also required to engage in daily static physical activity for 15 minutes in the morning prior to commencing classes.

Sadly, however, as a result of the educational rat race these guidelines are observed in the breach more so in the National schools.

Thus given the alarming increase in childhood obesity and type 2 diabetes in our school children and the effects on the body, there is much to be said for adding a 4th R - ‘running’ to the three traditional Rs in our schools. Doing so, coupled with healthy nutrition and restriction of television and internet usage will definitely help stem the epidemic of childhood obesity and type 2 diabetes while improving overall health and possibly even improving academic performance.

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