Physical activity (part. 1)
Introduction. In the battle for weight control and general good health, a lot of attention has been paid to the type and amount of the food and drink we consume.
Less attention has been given to the amount of energy we use up by being physically active.
Yet the two are closely linked.
Unlike our ancestors, we do not generally need to exert a great deal of energy to find food.
Advances in technology through motorised transport, automation, and labour-saving equipment, mean that there are fewer opportunities to exert energy for most people. It has been shown that around 70% of populations in westernised countries are not sufficiently active for optimal health and weight maintenance. What do we mean by "physical activity"? Physical activity, exercise, fitness - all of these terms are routinely used to refer to being physically active. Yet, in scientific terms, they all mean slightly different things. The most commonly used terms are defined in the table below.
|DEFINITIONS RELATED TO PHYSICAL ACTIVITY|
|Physical activity||All bodily movements that result in energy expenditure. This includes daily routine activities such as household jobs, shopping, work.|
|Exercise||Planned and structured repetitive movements designed specifically to improve fitness and health.|
|Sport||Physical activity that involves structured competitive situations governed by rules. In many European countries, the term sport is used to include all exercise and leisure time physical activity.|
|Physical fitness||A set of attributes such as stamina, mobility, and strength that relate to ability to perform physical activity|
Physical activity refers to all energy expended by movement. The major contributors are everyday activities that involve moving the body around, such as walking, cycling, climbing stairs, housework, and shopping, with much of it occurring as an incidental part of our routines.
Exercise, on the other hand, is a planned and purposeful attempt, at least in part, to improve fitness and health. It might include activities such as brisk walking, cycling, aerobic dance, and perhaps active hobbies such as gardening and competitive sports. Fitness is largely the result of our levels of physical activity, however genetic factors also play a role, with some lucky individuals having a natural capacity and physique to excel at certain activities.
This becomes more noticeable in competitive sports, such as distance running or weight lifting, where the best performers often have a genetically superior body that is in peak condition through vigorous training.
The important point to remember though is that evidence to date shows it is regular participation in physical activity (rather than any inherited component of fitness) that is linked to good health. This means that everyone, whether they are naturally athletic or not, can benefit from being more active! What are the benefits of physical activity? The benefits of being physically active are numerous and range from a reduced risk of certain diseases and conditions to improved mental health. Coronary heart disease and stroke Coronary heart disease (CHD) is the leading cause of death in Europe. Maintaining an active lifestyle and at least a moderately high level of aerobic fitness can halve the chances of either dying from or contracting serious heart disease.
The benefits of exercise on heart health can be felt at even moderate levels of activity with the greatest benefits being seen when sedentary individuals become moderately active. Regular walking, cycling or four hours of recreational activity per week are all associated with a reduced risk of heart disease.
Physical activity has also been shown to aid recovery from heart disease with exercise-based cardiac rehabilitation programmes effective in reducing further deaths. The effects of physical activity on stroke are less clear with studies showing inconsistent findings. Obesity and overweight Weight maintenance is the enery intake and energy expenditure. When intake is higher than expenditure over a certain period of time overweight and obesity develop. It is thought that obesity is a direct result of changes in our environment including the increased availability of labour saving devices, motorised transport, home screen entertainment and easier access to calorie rich foods at a lower cost.
The incidence of obesity has trebled in the last 20 years and in European countries 10-20% of men and 10-25% of women are now obese (Body mass index>30). Evidence is mounting that a reduction in levels of physical activity is a major factor in this trend. In fact, it appears that the amount of physical activity undertaken may be an even more important determinant of obesity than energy (calorie) intake. There are several studies that show the benefits of an active and fit lifestyle for the prevention of obesity. In particular, activity appears to help protect against the weight gain typical of middle age. In those who are already overweight or obese, exercise can assist with weight loss when combined with a low-energy (low calorie) diet and improves body composition by preserving muscle tissue and increasing fat loss.
Physical activity is also effective in reducing abdominal fatness or "apple shape" (where fat deposits accumulate around the stomach and chest area), the fat distribution associated with an increased risk of diabetes and heart disease. Furthermore, those who maintain exercise are more likely to sustain any weight loss over the long term. Perhaps the greatest benefit of physical activity for obese individuals is its effect on their health risk profile. It has been shown that obese people who manage to keep active and fit reduce their risk of heart disease and diabetes to levels consistent with those of non-obese individuals. This would suggest that it is not unhealthy to be fat as long as you are fit. To know more about obesity & overweight. Adult onset diabetes The incidence of type 2 diabetes has risen rapidly. This is often attributed to a rise in obesity, however, there is strong evidence to show that inactivity is also a risk factor. Studies indicate that more active individuals have a 30-50% lower risk of developing diabetes than their sedentary peers. Exercise has been shown to delay or possibly prevent glucose intolerance turning into diabetes and also has benefits for those who are already diagnosed with diabetes.
A small number of well designed studies have shown that exercise such as walking or cycling, carried out three times a week for 30-40 minutes, is able to produce small but significant improvements in glycaemic (blood sugar) control in diabetics. Cancer Being physically active appears to reduce the risk of certain cancers, with moderate to vigorous activity offering the greatest protection. For example, being physically active reduces the risk of developing colon or rectal cancers by 40-50%. Physical activity may also have an impact on some other cancers but evidence is still being gathered.
Bibliography * Andersen, L.B., Schnor, P., Schroll, M., & Hein, H.O. (2000). All-cause mortality associated with physical activity during leisure time, work, sports, and cycling to work. Archives of Internal Medicine, 160, 1621-1628.
* Biddle, S.J.H., Fox, K.R., & Boutcher, S.H. (2000). Physical activity and psychological well-being. London: Routledge.
* Bijnen, F.C., Feskens, E.J., Caspersen, C.J., Nagelkerke, N., Mosterd, W.L., & Kromhout, D. (1999). Baseline and previous physical activity in relation to mortality in elderly men: the Zutphen Elderly Study. American Journal of Epidemiology, 150, 1289-1296.
* Medicine and Science in Sports and Exercise (1999), Nov; 31 (11 Supplement).
* Blair, S.N. & Hardman, A. (1995). Special issue: Physical activity, health and well-being - an international scientific consensus conference. Research Quarterly for Exercise and Sport, 66 (4).
* Fogelholm, M., Kukkonen, M., & Harjula, K. (2000). Does physical activity prevent weight gain: A systematic review. Obesity Reviews, 1, 95-111.
* Lawlor, D. A., & Hopker, S. W. (2001). The effectiveness of exercise as an intervention in the management of depression: systematic review and meta-regression analysis of randomised controlled trials. British Medical Journal, 322, 1-8.
* Prentice, A.M., Jebb, S.A. (1995). Obesity in Britain: Gluttony or Sloth. British Medical Journal, 311, 437-439.
* Sports Council and Health Education Authority. (1992). Allied Dunbar National Fitness Survey. London: Sports Council/HEA.
* US Department of Health and Human Services (PHS). (1996). Physical activity and health. A report of the Surgeon General (Executive Summary). Pittsburgh, PA: Superintendent of Documents.