manson

What is physical activity?
Physical activity is an important component of our daily energy expenditure. It is defined as bodily movement that is produced by the contraction of muscle and that substantially increases energy expenditure (USDA, 1996). Many different types of activity contribute to our total physical activity, all of which form an integral part of everyday life. Total physical activity includes occupational activity, household chores, care giving, leisure-time activity, transport (walking or cycling to work) and sport. Physical activity can further be categorised in terms of the frequency, duration and intensity of the activity.
Many methods have been used to describe the intensity of physical activity, one of which is the use of metabolic equivalents (METs). One MET is a person’s metabolic rate (rate of energy expenditure) when at rest; multiples of this can be used to indicate the intensity of an activity. Classifications of light, moderate and vigorous physical activity are often used. Intensities and energy expenditure for common types of physical activity are shown in the table attached below.

Physical activity recommendations
The Department of Health recommends that in order to benefit health, individuals should participate in at least 30 minutes of at least moderate intensity activity on five or more days a week. Moderate intensity activity is defined as a level of activity that will:
• Lead to an increase in breathing rate
• Lead to an increase in heart rate (the pulse can be felt during this level of activity)
• Lead to a feeling of increased warmth, possibly accompanied by sweating
Greater health benefits will of course be achieved by participating in a higher total period of activity over a week, but vigorous activity is not a requirement for a beneficial effect on health. The recommended 30 minutes of moderate intensity activity does not have to be taken all at once; for example three brisk walks of 10 minutes duration during the day would be equally beneficial.
These recommendations also apply to older adults, and in addition older people should aim to maintain mobility through daily activity; activities that promote and improve balance, strength and co-ordination are particularly encouraged.
Children and young people are recommended to engage in at least 60 minutes of at least moderate intensity exercise every day. Activities that increase muscle strength and flexibility and also improve bone strength (i.e. weight bearing activities that strengthens the skeleton) should be included at least twice a week.
In order to prevent obesity, many individuals will need to participate in between 45 and 60 minutes of moderate intensity physical activity each day.
Current levels of physical activity
Adults
Physical activity levels in England are low and a cause for concern across virtually all sections of the adult population and amongst some groups of children, notably teenage girls. Only 37% of men and 25% of women achieve at least 30 minutes of moderate intensity physical activity on 5 or more days of the week. Furthermore 35% of men and 41% of women are particularly inactive as they achieve less than 30 minutes moderate intensity activity over a week (Health Survey for England, 1998). Over the last 20 to 30 years, despite an increase (albeit a small increase) in the proportion of people participating in physical activity during leisure time, physical activity levels have fallen as a result of physical activity becoming a smaller part of the daily routine. For example, there are more labour-saving devices in the home, fewer manual jobs in society, and cars are being used more for shorter journeys.
Children
There are also concerns about activity levels of children in England; although more active than adults, many may not be taking part in enough exercise for good health. Seventy percent of boys aged 2-15 years achieved at least 60 minutes of physical activity on all 7 days covered by the Health Survey for England (2002), whereas only 61% of girls aged 2-15 years achieved this level of physical activity. This level of activity tends to be maintained up to 15 years of age in boys, but falls in girls as they reach 15 years old. Seventeen percent of boys and 22% of girls are inactive, and only achieve less than 30 minutes of activity per day. This is one possible reason for the increase in prevalence of obesity in children.
Effects of physical activity on health
There is strong scientific evidence to suggest that physical activity benefits well-being and is necessary for good health. Physical activity has beneficial effects on a wide number of diseases but, importantly, also plays a role in disease prevention. Participating in physical activity has been shown to reduce the risk of a number of chronic diseases including cardiovascular disease (CVD) and type 2 diabetes as well as the risk of premature death. Physical activity has been demonstrated to benefit all people regardless of age, stage of life, gender and socio-economic status and it is never too late to start being more active.
Children benefit from physical activity because it improves disease risk factors, strengthens the skeleton, improves mental wellbeing and helps to maintain a healthy body weight. Adults, particularly older adults, will benefit from increasing physical activity levels through protection against a number of diseases and through achievement and maintenance of a healthy body weight. In addition, individuals will benefit from improved mental health, well-being and muscle and bone health. In older people, activities that promote strength, coordination and balance are particularly valuable for maintaining capability for everyday activities.
Cardiovascular disease
Physical inactivity and low fitness are major independent risk factors for coronary heart disease; those who are inactive and unfit have almost double the risk of dying from coronary heart disease. Physical activity also has a beneficial effect on preventing stroke and modifying cardiovascular risk factors such as high blood pressure and blood lipids (e.g. cholesterol).
Overweight and obesity
Lack of physical activity is an important factor contributing to the increasing prevalence of obesity. Any movement will contribute to energy expenditure and will therefore contribute to energy balance. Maintaining activity throughout life is important for preventing obesity, and increasing physical activity is an important element of any weight loss plan. Incorporating more physical activity into a weight loss plan can maximize fat loss, preserve lean tissue, improve fitness and offer other health benefits.
In today’s sedentary lifestyle, more physical activity needs to be incorporated into our daily lives in order to prevent obesity. In the At least five a week report by the Chief Medical Officers (2004), it is recommended that, for many people, 45-60 minutes of moderate intensity activity per day is required to prevent obesity. Those who have been obese, and have successfully lost weight, may need to include 60-90 minutes of activity per day to avoid regaining weight.
Diabetes
Physical inactivity is a major risk factor for type 2 diabetes; active people have a 33-50% lower risk compared with inactive people. Increasing physical activity is also effective in reducing the risk of type 2 diabetes in those people who are already at high risk. Furthermore, regular physical activity can produce metabolic benefits that can help manage the condition in type 2 diabetes patients.
Cancer
Physical activity is associated with a reduced risk of certain cancers, particularly colon cancer and post-menopausal breast cancer. The most active individuals have, on average, a 40-50% lower risk of colon cancer compared to the least active. Physical activity can also have an indirect effect on reducing cancer risk through its effects on body fatness, as a number of cancers are associated with obesity (see diet and cancer).
Muscle and bone health
Activities that produce physical stresses on bones (e.g. running, dancing, skipping) are necessary throughout life to provide protection against osteoporosis. In adolescents this type of physical activity strengthens the skeleton by increasing peak bone mass. After adolescence, physical activity reduces the rate of bone loss which takes place naturally with ageing. Physical activity may also delay progression of osteoarthritis and, specifically, activities that promote strength and balance may be important for older people because they may reduce the risk of falls.
Improving physical activity levels
Incorporating more physical activity into daily routines will be the easiest way to increase physical activity, for example walking or cycling instead of driving (particularly for short journeys) and taking up more active hobbies such as gardening. Within the workplace there are fewer opportunities for increasing physical activity, but stairs could be used in preference to the lift and individuals could walk to speak to colleagues rather than use telephones or e-mail. Overall, the benefits associated with participating in the recommended levels of physical activity are great.
There are a number of barriers that need to be overcome before people will engage in more physical activity. Many people see physical activity as unenjoyable, hard work and requiring a lot of effort and time (and sometimes cost), and it is often perceived to be a great challenge to change from a sedentary lifestyle to a more active one. However, physical activity can be very enjoyable and can offer many social and mental health benefits. Individuals need to understand, and want, the many benefits of physical activity before they will commit to increased activity. Physical activity is an opportunity to improve vitality, increase fitness, achieve and maintain an optimal body weight as well as an opportunity to gain numerous health benefits.

Reference: Department of Health (2004) At least five a week. Evidence on the impact of physical activity and its relationship to health. A report from the Chief Medical Officer. Department of Health. London.

© British Nutrition Foundation 2008

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paulo

great post mate

manson

Thanks although can't claim credit lol, came across it whilst trying to sort out my diet.

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