Physical activity (part. 3). What are the risks associated with physical activity? No action is without risk and exercise is no exception. For example, the risk of sudden cardiac death increases by a factor of 5 during vigorous exercise for fit individuals and by a factor of 56 for unfit individuals.
There is also an increased risk of injury, particularly to feet, ankles and knees, while taking part in exercise or vigorous sports. Finally, much press attention has focussed on "exercise addiction", whereby people become 'hooked' on exercise to the detriment of other aspects of life such as work and social relationships.
Although a syndrome of exercise dependence has been identified, it is extremely rare and more likely to accompany other mental problems such anorexia nervosa, excessive neuroticism and obsessive-compulsive disorders.
How much physical activity do we need? For many years, exercise and health promoters adopted training guidelines for the improvement of cardiovascular fitness that involved quite vigorous exercise using large muscle groups in continuous work for a minimum of 20 minutes at a vigorous intensity (equivalent to 60-80% of maximum heart rate). Unfortunately, this level of exercise proved too difficult to achieve for the majority of people, with most remaining inactive.
The most recent recommendations from the USA and the UK are for regular bouts of activity at moderate levels of intensity. Moderate intensity physical activity, equivalent to brisk walking, is thought to be achievable by a much larger percentage of the population as it can be reasonably incorporated into daily routines and is less physically demanding. A daily 20-minute brisk walk will make a difference of 5 kgs per year and for most people there will be improvements in cardiovascular fitness and other physical and mental health benefits. Current recommendations emphasise brisk walking on most or all of the days of the week for 30 minutes at a time. Evidence suggests that the same amount of exercise taken in two or three shorter bouts can be almost as effective and may also be more manageable on a daily basis.
Different types and intensities of activity will improve different elements of health and fitness. For example, a gentle stroll at lunchtime, although not sufficiently intensive to create an improvement in circulatory fitness, may provide a healthy break from work, enhance mood and reduce stress, while also contributing to weight management. For those who dislike or are unable to do planned exercise, avoiding or reducing the time spent in sedentary pursuits such as watching television may be just as useful. Simply standing for one hour instead of sitting watching TV each day, for example, will expend the equivalent of 1 to 2 kgs of fat per year. To provide maximum benefit for all areas of the body, a range of specific strengthening and stretching exercises is also needed. This is particularly important for older people.
The moderate exercise message does not overrule the extra benefits provided by more vigorous activity, particularly in terms of improving heart health and glucose metabolism. However, most people will need to build up to those levels over a period of many months. The recommendations from the Quebec Consensus Statement on Physical Activity, Health and Well-Being provide useful physical activity guidelines.
SUMMARY OF RECOMMENDATIONS FROM THE QUEBEC CONSENSUS STATEMENT ON PHYSICAL ACTIVITY, HEALTH AND WELL-BEING (1995)
* Involve large muscle groups
* Impose more than a customary load
* Require a minimum total of 700 kcal/week
* Be performed regularly and if possible daily
In practice, sustained rhythmic exercise, such as brisk walking for 20--30 minutes would fulfil this requirement in most adults. For further maximum health benefits, activities should:
* Include some periods of vigorous activity
* Include a variety of activities
* Exercise most of the body's muscles, including trunk and upper body
* Expend up to 2000 kcals/week
* Be maintained throughout life
Conclusions When people become more active, they reduce their risk of early death from heart disease, some cancers and diabetes, they manage their weight better, increase their tolerance for physical work and improve their muscle and bone health. They are also likely to improve their psychological well-being and life quality. Not only does physical activity have the potential to add years to life, but the evidence is also accumulating that it can add life to years.
Sedentary living is at epidemic status in Europe. The evidence linking inactive living with a range of physical and mental diseases and disorders is now accepted by leading authorities worldwide. At the moment, the situation seems to be worsening rather than improving. Costs in terms of human suffering, lost productivity and health care are high. The solution on the surface appears to be simple. People need to move more and move more often. Unfortunately, the majority of the population, particularly those most likely to benefit, such as the middle aged and elderly, are unlikely to become more active without substantial intervention.
The promotion of physical activity requires concerted effort from several agencies to help individuals reduce their sedentary time and increase their physical activity, and to change the environment to encourage people to be more active. National, regional and local governments need to work with planners of transport and building, schools, work places, and health authorities to encourage more activities such as walking, cycling, sport and active leisure. At the same time, it is the responsibility of individuals to step back and reappraise their priorities with a view to establishing lifestyles that include more daily physical activity.
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