Benefits of Exercise and Increasing Fitness Levels

The fitness levels attained depend on the degree of aerobic and cardiovascular fitness. The US Surgeon-General's report recommends 30 minutes or more of moderate to intense activity virtually every day of the week. Once achieved, cardiovascular fitness alone can reduce the risk of cardiovascular events by almost 50%, an outcome that is far better than any available lipid-lowering drug.

Since sedentary individuals are unaccustomed to physical activity, they may have a 22% risk of acute myocardial infarction upon initiating an exercise program. Nevertheless, the overall long term benefit is much higher than to remain sedentary or be obese. The risk of sudden cardiac death from overexertion during exercise is relatively rare: 1 in 36.5 million exercise hours in women and in 1 in 19 million exercise hours in men.

Apart from genetic components, moderate physical exertion and a low-fat diet could improve cardiovascular fitness and promote atheroma plaque regression in the coronary arteries.

According to the US-based National Health Education and Nutrition Examination Survey, aerobic sports, such as walking, running and swimming, conferred greater reductions of cardiovascular complications than anaerobic sports that involves sudden bursts of exertions.

In the quest to create an effective anti-ageing solution, scientists at the Pennington Biomedical Research Centre in Baton Rouge, Lousiana, studied age-related decline of bodily functions, namely the accumulation of oxidative damage in the body's proteins, fats and DNA. Oxidants called free radicals are damaging chemicals that are produced when food is converted to energy by cellular structure called mitochondria.

Since previous studies have shown that free radicals can damage the DNA of cells that could lead to premature ageing, scientist believe that calorie restriction lowers free radical production and, therefore, induces a slower ageing process. The team conclude that limiting calorie intake without malnutrition could extend lifespan.

Exercise efficiency is defined as how much energy the body expands to perform a given activity. It is a known fact that as people age, there is a decline in exercise efficiency. Older adults may have to work harder than younger people to perform the same physical activity. The older body also needs more oxygen to perform the same work as it did when it was young.

But recent findings, published in the Journal of the American College of Cardiology, suggest that the decline in exercise efficiency, which appears to arise largely from inactivity, can be reversed with regular exercise.

In a study, researchers from the University of Washington in Seattle compared sedentary adults in their 60s and 70s with those in their 20s and 30s. They found that older adults used 20% more oxygen to walk at the same speed as their younger counterparts. But after a six-month exercise program of walking, jogging, biking and stretching, the senior participants were able to improve their exercise efficiency. Regular exercise of 90 minutes, three days per week, improved exercise efficiency by 30%, versus only 2% among their younger counterparts.

Reference:

JAMA 2006; 295: 1399-1403, N Eng Journal Med 2000; 343: 1355-611

Ann Intern Med 2006; 144: 485-95