Both adults and children in Britain are less active and less fit than previously. Obesity is increasing and is related to inactive lifestyles. Physically active people have reduced risks of a range of disorders, including heart disease, depression, and osteoporosis; it also improves well-being. Both cycling and walking are good exercise: walking or cycling to school or work is as effective as a training programme and can fulfil the recommendations for exercise.

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Physical activity is an optional behaviour. It is a global term referring to any bodily movement produced by the skeletal muscles that results in energy expenditure.

Exercise is sometimes used as a synonym for physical activity but often refers to participation in sports, gym-based activities or organised exercise classes.

Physical fitness is an achieved physiological condition. It is a set of attributes which people have or can acquire that relate to their ability to perform physical activity. An individual's level of fitness is determined partly by heredity but can be acquired through physical activity.

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People who are regularly physically active halve their risk of coronary heart disease and reduce their risk of stroke by a quarter. They have a lower risk of developing:

Physical activity also improves mental well-being and improves control of weight, high blood pressure, and diabetes.

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The word 'normal' is a statistical term, meaning average ('within normal limits'). It does not mean 'healthy'. A good example of this is cholesterol levels in the UK population: the range derived from two standard deviations either side of the mean is far higher than is desirable.

Current recommendations

Adults: a total of 30 minutes moderate activity at least five days per week eg two 15min brisk walks.

Children: a total of 60 minutes moderate activity at least five days per week.

These can be accumulated over the day in bouts of at least 10minutes.

Current activity levels

Adults

The 1992 Allied Dunbar National Fitness Survey identified UK adult population groups who were particularly sedentary:

Population groups with special access and/or communication needs were also identified, including people from black and minority ethnic groups, and disabled people.

In 2003, only 32% of men and 26% of women in London were sufficiently active, with 36% of men and 41% of women in London being sedentary (engaging in less than one session of 30 minutes of continuous moderate intensity physical activity per week). These activity levels were the lowest of any English region for men but amongst the highest for women. Although 52% of young men in London (aged 16-24) fulfilled the current recommendations for physical activity, only 27% of young women in London did so. There was no regional trend in type of activity except that participation in heavy manual activity/gardening/DIY was half as common in London as in the rest of the country (16% of male Londoners vs 34% elsewhere; 6% of women in London vs 13% elsewhere).

Across England in 2003, older people remained more likely to lead a sedentary lifestyle than younger people - among 16-24-year-olds, 18% of men and 31% of women were sedentary, while among 65-74-year-olds, 52% of men and 56% of women were sedentary. Nationally, 23% of men and 19% of women had participated in walking in the previous 4 weeks in 2003. This declined with age, particularly in men (35% aged 16-24, 23% aged 45-54, and 8% aged 75). High physical activity levels were more common in those with higher household incomes and significantly related to socio-economic circumstances, as measured by NS-SEC, being highest among ‘Small employers and own account workers’ for men and women, and also higher among men employed in ‘Lower supervisory and technical’ and ‘Semi-routine and routine occupations’. In England in 1995, only 36% of men and 24% of women were regularly active at a moderate level but 56% of men and 52% of women believed they did enough exercise to keep fit.

The most common form of physical activity in 2003 in England for men was participation in sports and exercise (31% of men, 25% of women) and heavy housework for women (17% of men, 30% of women). Heavy housework as an activity changed little for either sex between the ages of 25 and 74, unlike the steady decline in sports and exercise.

Data is available from:

Children

Levels of physical activity in children have been declining. An HEA survey published in 1998 found that children aged 9-15 in England were getting 4.7 hours of activity a week on average, both during and outside school. Between the ages of 11-15 there is a marked decrease in the proportion of girls who are active daily, while among the boys there is less change. However, there was a decrease in the proportion of boys and girls nationally between 1997 and 2002 who were sedentary, with a particularly large increase in girls’ activity.

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Improvements in physical fitness could reduce risks of death by 60% (more than the 50% risk reduction from quitting smoking. Fitness is more important but physical activity is also required for fitness to be protective against IHD

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Self-selected walking speeds tend to remain constant in adult life until the 6th decade then decrease sharply by 12-16% after that. Most pedestrian crossings assume a walking speed of around 4km/h but those in their 8th decade are often more comfortable walking at 3.2km/h. Gradually increasing physical activity to increase fitness and muscle strength may increase possible walking speed and therefore safety and independence.

Regular cyclists have a level of fitness equivalent to that of people 10 or more years younger.

Inactivity leads to a progressive reduction in the capacity for physical exertion. Greater effort becomes necessary for shorter and slower activity, with fatigue developing faster. Both muscle strength and cardiovascular fitness are affected by prolonged or habitual inactivity. Much of the deterioration of function attributed to increasing age may actually be due to decreasing activity, leading to a worsening in capacity to exercise. A vicious spiral develops.

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Cycling at 10mph uses 7calories/min on average, adequate for health benefits. Walking a mile in 20 minutes (slower than the 3.5 - 4.5mph most often recommended for health benefits to accrue to the middle-aged) expends the same amount of energy as cycling at 9.4mph for 16 minutes, running a mile in 10 minutes, swimming breast stroke for 10 minutes, medium-intensity aerobic dancing for 16 minutes, or playing football for 12 minutes.

Regular "brisk" or "fast" walking can improve cardiovascular fitness. Walking at 6.4km/h (4mph) for >3.5hrs/wk halved the risk of first coronary event or fatal IHD in 9½ years follow-up. The age-standardised death rate from coronary heart disease (CHD) was also inversely related to speed of usual walking pace. Those who strolled had a high rate of co-morbidity, were otherwise sedentary, and were more often smokers. CHD deaths and hospital admissions were reduced by 26% in older people who walked >4h/wk compared with <1h/wk, even when adjusted for other, more vigorous activities.

Exercise tolerance and quality of life in people with congestive heart failure can be increased and fatigue and shortness of breath reduced by a progressive walking programme. Relatively low intensity walking appears to suffice to improve the symptom of intermittent claudication.

Walking also enhances insulin sensitivity and glucose uptake into muscle. Effective activity in preventing diabetes included "very brisk walking" (8.0km/hr; 5mph) or "brisk walking on soft surfaces such as sand or grass". Brisk walking in middle-aged or slower walking in older people would be sufficient activity (50-60% of VO2max) to maintain stable blood glucose levels.

Bone density is higher in the legs and trunk of postmenopausal women who habitually walked >7.5miles/wk compared with those who walked <1mile/wk. Aerobic activity, including walking, jogging or cycling, can improve stamina. In healthy sedentary adults, walking led to reductions in mood disturbance in women and increased positive affect in men. Different intensities of walking all improved quality of well-being in people with chronic pulmonary disease in proportion to improvement in exercise tolerance in comparison with controls. Walking improved pain in people with osteoarthritis and reduced anxiety and depression. Other benefits to well-being, from companionship and pleasant physical surroundings, are not necessarily relevant to active transport in London.

Walking uses 1cal/kg bodyweight, almost independent of pace, so walking too slowly to increase fitness can still aid weight control. For example, one mile on the level requires 65calories for a 75kg man and more in heavier individuals.

Incorporating activity into routine daily living can facilitate better compliance with the recommendations for physical activity by the general population than requiring attendance at sports facilities. It is cheaper, less demanding of additional time, and more readily accessible, important considerations since costs, lack of time, and lack of facilities are the main reasons given for inactivity. The average distance walked by Londoners fell by 15% from 1989/91 to 1999/2001. Cycle journeys also fell by 13% in the 1990s but are now rising again.

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The overall incidence of primary cardiac arrest is 55-60% lower in people with high compared with low leisure time physical activity. Although the risk of sudden death is higher during exercise than while inactive, the overall risk of primary cardiac arrest in those who are habitually active and physically fit is only 40% that of sedentary men. Even after allowing for conventional risk factors, the overall risk of cardiac arrest is lower among habitually vigorously active men than sedentary men. This is because a relatively small proportion of the time is spent in vigorous activity while the protective effects last all day. However, two cohort studies have found that the most active men had an increased risk of IHD. Further analysis of one showed that this applied only to men with hypertension.

Other risks include hypo- or hyper-glycaemia in diabetics; precipitation of asthma symptoms (usually prevented by prophylactic use of a bronchodilatory); and musculo-skeletal injuries.

Lower intensity activities, such as walking and cycling, are less likely to result in any of the above. Low impact exercise (including running and jogging) does not increase osteoarthritis except in those with a history of knee injuries or anatomical abnormalities. While cycling can be injurious to those with osteoarthritis of the knee, walking is the exercise of choice for people with arthritis. Walking at any speed is low impact and is also self-regulated in intensity and duration, so the risk of injury is low.

There is a risk of injury or death from road traffic collisions but the benefits of cycling far outweigh the risks from collisions. Air pollution is greater inside cars than near the kerb or on the pavement. Although cyclists may breathe more deeply, they are also exposed for shorter periods than drivers in more congested areas.

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Date	Title	Format	View
7 Dec 2006	Active People Survey: headline results for London
7 Dec 2006	Active People Survey: national headline results

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CMO. At least five a week. London: DH, 2004 . (A review of the evidence for the health effects of physical activity at different ages).

DH. Choosing Activity: A Physical Activity Action Plan

Capital LHO Down: A Briefing On Nutrition, Physical Activity & Obesity

HDA. Effectiveness Of PH Interventions For Increasing Physical Activity Among Adults - Full Review

HDA. Effectiveness Of PH Interventions For Increasing Physical Activity Among Adults - Summary

A review of the health effects of physical activity from the Chief Medical Officer's working group is expected to be published summer 2003.

The following Report sets out the latest research evidence of the benefits of physical activity for health. It will be of interest to those concerned with formulating and implementing policies or programmes that utilise the promotion of physical activity, sport, exercise and active travel to achieve health gain, in particular the NHS, specifically public heath and primary care trusts.

A review on the health effects of physical activity was part of a review of the health effects of transport prepared for the London Regional Office of the NHS Executive. It was published both in full and in summary form.

Watkiss P, Brand C, Hurley F, Mindell J, Pilkington A. Informing transport health impact assessment in London. London: NHS Executive London, 2000.

Watkiss P, Brand C, Hurley F, Pilkington A, Mindell J, Joffe M et al. On the Move. Informing transport health impact assessment in London. London: NHS Executive. AEA Technology, 2000.

Selected scientific references on physical activity and health:

Health effects of physical activity

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• Pro-active South London
• Choosing Activity: A Physical Activity Action
• Effectiveness Of PH Interventions For Increasing Physical Activity Among Adults - Full Review
• Effectiveness Of PH Interventions For Increasing Physical Activity Among Adults - Summary
• Health Survey for England 2003: Risk factors for cardiovascular disease
• Percent of children with adequate activity by sex and Region
• Young adults activity levels by Region
• Children's activity levels and types by age, sex and Region

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