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Despite gaps the size of the Grand Canyon,
Britain now has a cycleway network, but not because somebody in
the ministry suddenly saw the light. It was achieved by cycling
advocates battering down doors to talk the talk with Whitehall and
city hall, planners and providers. They spoke the same language,
knew their subject and won concessions.
As many predicted, providing cycling facilities
alone has not been the panacea to our urban traffic problems, and
the number of bums on bikes continues to drop.While the battle for
appropriate infrastructure is unrelenting, a new front has opened
up - one with the potential to achieve everything planners and highway
engineers were never going to. After a decade of being told by the
British Medical Association that cycling is good for mind and body,
the health authorities have finally taken note.
Around the country all manner of interesting
initiatives are being funded by health, from cycling on prescription,
to adult cycle training classes, to something like Think Cycling
in Cambridge, exploring how best to market pedal pushing. Though
in their infancy, these projects are specifically geared to encouraging
the public to pedal their way back to health and fitness with the
object of trimming a small fortune on the NHS budget.
But when cycling initiatives are bidding
for funding from the same pot that consultants are lobbying for
new dialysis machines and scanners, it is not sufficient to simply
argue that cycling is exercise and exercise is good news. We need
to know our stuff and talk the talk. So it was that the Nottingham
Health Authority commissioned me to trawl through the research and
produce a plain English report outlining the facts.
There is actually precious little research
specifically about cycling, and much has had to be extrapolated
from papers studying exercise. For example, a major survey in the
U.S. involving 13,000 people recorded a substantial difference between
the fit and the unfit, concluding that: 'higher levels of physical
fitness appear to delay all-cause mortality, primarily due to lowered
rates of cardiovascular disease and cancer'. Exercise in moderation
undoubtably contributes considerably to reducing the risk of premature
death.
Of all the forms of exercise available to
the public, swimming, cycling and brisk walking we're proven to
offer the greatest benefit for the least expense, inconvenience
and risk of injury. Of those, cycling came out on top because it
is also a means of transport and could be incorporated into a working
day. Thus a study among factory workers discovered that regular
cyclists enjoy a level of fitness equivalent to that of individuals
ten years younger.
Another piece of research found that cycling
60 miles a week from the age of 35 could add two years to your life
expectancy, and a Dutch study concluded that everyday or utility
cycling yields much the same improvements in physical performance
as specific training programmes. For those with a low initial fitness
level, a single trip distance of three kilometres a day was found
to be sufficient to greatly improve physical performance and general
health.
Why is exercise beneficial?
The human body is designed for movement.
To develop and maintain peak levels of fitness, exercise must be
carried out on a regular basis and must be relatively strenuous.
The recommended amount from a health perspective is about twenty
to thirty minutes of moderate exercise three times a week, though
the level of activity which produces a benefit is a factor of the
individual's initial level of fitness.
The energy which is needed for exercise comes
from two major series of chemical reactions - anaerobic and aerobic.
Of the two, aerobic exercise is of primary importance in producing
health benefits. During aerobic exercise, oxygen is gradually released
to the muscles, fuelling efficient, energy-yielding reactions. Thus
aerobic exercise can be sustained over a much longer period than
anaerobic exercise, with the following beneficial effects…
Muscle-strength
Muscle-endurance and strength develop from
early childhood, but recent studies indicate that exercise will
result in gains in muscle-strength even in extreme old age. To facilitate
an independent lifestyle it is necessary to maintain an adequate
level of muscle-strength, particularly in the major muscles associated
with the movement of limbs.
The variety of muscles exercised while pedalling
is limited by comparison with many forms of exercise, but cycling
has built-in rest periods between its submaximal rhythms which reduce
anaerobic elements, fatigue and the accumulation of lactic-acid.
The rhythmic contraction and relaxation of the large limb muscles
can therefore be sustained over long periods without fear of injury,
particularly as the body is supported on a saddle.
Asthma and bronchitis
Adequate respiratory function is essential
for good health. It is a composite of the purely mechanical process
of breathing and the ability of the heart and the blood to transport
oxygen to the tissues and carbon dioxide back to the lungs. Vigourous
exercise increases deep breathing, during which the lungs take in
more oxygen and dispel more carbon dioxide than when our bodies
are at rest. Regular exercise therefore hones the breathing muscles,
improving the long-term delivery of oxygen to muscles and tissue.
Vigourous cycling is an excellent way of
stimulating deep breathing. It is particularly beneficial for patients
with chronic conditions such as asthma and bronchitis. While asthmatics
need to be careful, there is evidence that moderate exercise extends
their capacity for exertion. There are also many cases of patients
with long-standing bronchial problems taking up cycling and making
a full recovery.
Diabetes
Diabetes exerts a huge toll on individuals.
Several treatments are effective in preventing the devastating complications
of diabetes, but these are suboptimally used, and the disease itself
is chronic, progressive and degenerative. Recent research, however,
has found that diabetes may be prevented by lifestyle changes.
A study of 522 middle aged, overweight people
with impaired glucose tolerance showed that a lifestyle change which
includes regular exercise can reduce the risk of progression to
diabetes by a striking 58% over four years. Regular cycling can
reverse the proximal factors associated with diabetes such as obesity,
physical inactivity, high fat and energy diets, high blood pressure
and lipids (see below).
Mental health
Because it is so subjective, this is a grey
area, but evidence has been found linking exercise with endorphins
- substances with a calming effect produced by the brain. Stimulating
the body helps release endorphins which can lift depression and
relieve mental stress much like a psychoactive drug. Aerobic exercise
also helps to reduced mental stress in general, in the sense that
it raises tolerance to stress.
One study concluded that psychological improvements
often occur independent of fitness changes, possibly from factors
such as the sense of achievement and positive feelings of self-control,
or simply from social interaction while taking the exercise.
And hard cycling has been found to reduce
tension. In a study performed on exercise bikes, a group pedalling
for twenty minutes at 75-to-80% intensity were found to have muscles
twice as relaxed as a group exercising at 40% intensity. This decreased
muscle tension is thought to result in a greater degree of relaxation
and reduced stress.
Anecdotally, many people affirm they 'feel
good' during or for some time after exercise. While subjective responses
prove nothing to the scientists, cycling appears to contribute to
mental well-being simply because of the positive enjoyment that
people gain from it. It confers a feeling of freedom and independence,
and a sense of achievement derived from satisfying journey-needs
entirely through one's own efforts.
Cardiovascular disease
Diseases of the heart and circulation, together
with cancer, are the commonest causes of death in Britain. Coronary
heart disease accounts for about 80% of heart diseases and is the
greatest single cause of death, responsible for a third of all deaths
in men and a quarter in women. The treatment of heart related conditions
cost the NHS over £500 million in 1988 and it's only gone up. Added
to this are the costs to industry associated with time off work
(estimated at £1.8 billion) and the unquantifiable costs of personal
and family anxiety, limitation of activity, and so forth.
The heart pumps blood round the system, taking
oxygen to various parts of the body. The ease with which the heart
can carry out this task determines the amount of strain it experiences.
During vigourous exercise, blood flow can increase from 5 litres
to 25 litres a minute. This increase enables more oxygen to be delivered
to tissues, with most of it going to the exercising muscles.
The factors most commonly understood to be
associated with coronary heart disease are:
High Cholesterol Levels
Cholesterol can be broadly divided into the
good type or HDL (high-density lipoprotein), and the bad type or
LDL (low-density lipoprotein). The higher the ratio of HDL to LDL,
the more likely the heart and its coronary arteries are to be healthy.
If the ratio is low, the walls of the arteries fur up (atherosclerosis)
with deposits of cholesterol, resulting in a reduced flow of blood.
High levels of HDL cholesterol can help to remove some of the cholesterol
from artery walls and transport it to the liver where it is metabolised.
Many studies have shown that exercise leads
to changes in the proportions of high and low-density lipoproteins.
The level of LDL decreases and the level of HDL increases in response
to training, which should reduce the incidence of both atherosclerosis
and coronary thrombosis.
High Blood Pressure
Insurance statistics show that men with only
moderately high blood pressure (hypertension) can expect to die
about fifteen years before men with low blood pressure. Blood always
needs to be under pressure to circulate, but if the pressure rises
too high the heart has to work harder, again increasing the risk
of coronary problems. Regular exercise can lead to a fall in blood
pressure when this is already higher than normal, and is potentially
a major non-pharmacological method of lowering blood pressure.
Stress
Stress is difficult to define, though we
know that a certain amount is required for healthy functioning.
Studies have been unable to show precisely what role it plays in
heart disease, but stress produces adrenaline, which stimulates
the heart to beat faster. Under too much stress blood pressure rises,
the rate of blood coagulation increases and the liver releases sugar
and fats into the bloodstream to provide energy. An increase in
the blood coagulation rate increases the chances of blood-clots,
and the excess fat in the blood can be deposited in the arteries.
Until recently, people with heart conditions
were told to rest as a cure. However, the role of physical activity
and inactivity in causing and treating coronary heart disease has
increasingly come to the fore. Research over the years has confirmed
the major preventive role that daily exercise can play. Men whose
work or leisure activities involve vigourous exercise are less likely
than their non-exercising contemporaries to develop or die of coronary
heart disease. Several studies have suggested that only rather low
levels of activity are necessary to confer some degree of protection
against heart disease, both in terms of the intensity of effort
and of the total amount of exercise taken.
Obesity
According to insurance statistics, 7 per
cent of the adult population in this country are seriously obese
(i.e. more than 30 per cent above a desirable height/weight ratio),
and a government survey finds that one in three adults are overweight.
Obesity is associated with an increased risk of heart disease, hypertension,
late-onset diabetes, arthritis and bronchitis. Though there has
been some controversy about the value of exercise in weight reduction,
a brisk walk of about thirty miles will burn off a pound of fat.
About four to five calories a minute are
expended when cycling gently, three to four times higher than when
a person is sitting at rest. Cycling for half an hour a day uses
120 to 150 calories (i.e. on a routine five-day-a-week basis, up
to 750 calories, and over a year, up to 40,000 calories). The energy
value of one kilogram of adipose (fatty) tissue is about 7,700 calories.
Cycling for half an hour a day therefore expends an annual amount
of energy equivalent to that stored in over five kilograms of adipose
tissue.
Exercise also stimulates the metabolic rate,
enabling the body to extract a higher intake of vitamins, minerals
and trace elements from any given quantity of food. Strenuous exercise
may also help to maintain the metabolic rate for as long as twenty-four
hours after the exercise itself.
Direct evidence relating cycling to reduced
rates of coronary heart disease is sparse, but several related studies
can be mentioned. A short paper specifically about cyclists published
in the British Medical Journal showed that there was a decrease
in the incidence of myocardial infarction (pertaining to the muscles
of the heart) and ischaemic heart disease (pertaining to deficiencies
in blood supply) in all the cyclists studied, and a tenfold decrease
in the incidence of ischaemic heart disease in the over-75 group.
Another study took a group of patients with
heart problems and tested the effects on their heart of pedalling
an exercise bike. It concluded that 'home-based physical training
programmes are feasible even in severe chronic heart failure and
have a beneficial effect on exercise tolerance, peak oxygen consumption,
and symptoms. The commonly held belief that rest is the mainstay
of treatment of chronic heart failure should no longer be accepted.'
Conclusion
The major theme that emerges from the evidence
is that, for exercise to be beneficial, it has to be regular and
maintained throughout life. To improve or maintain fitness there
is a threshold intensity level which must be exceeded and this level
is dependent on the initial fitness level. It follows that the kind
of exercise which is ideal is one that can be entered at any level,
is conveniently undertaken on a day-to-day basis, requires no facilities,
is inexpensive, and is of minimum inconvenience to our daily routine.
For the majority of the population, walking and cycling meet these
criteria better than any other activity.
With 72% of all car journeys clocking under
five miles, there is the potential for a substantial modal shift
away from motorised transport towards cycling. Aside from boosting
the health of the nation, a move away would significantly reduce
air and noise pollution, greatly relieve urban congestion and the
associated stress, and massively improve our living and working
environments.
But there is concern in the medical profession
that encouraging cycling will lead to an increase in casualties
and fatalities on the road. This has not been the case in countries
where vulnerable road users are properly catered for. For example,
by distance travelled, cycling in the Netherlands is five times
safer than cycling in Britain. In Denmark it is 12 times safer,
and in both countries cyclists constitute a far greater portion
of the modal breakdown than in Britain.
Away from cycling facilities, the evidence
indicates that the more cyclists there are on the road, the safer
cycling in traffic becomes. In York, the policy of prioritising
healthy modes of transport and restraining motor traffic has led
to casualty reductions well above the national average. The city
has one of the largest pedestrian and cyclist specific networks
in Europe, with over 13% of city staff walking to work and 22% of
work related trips being made by bicycle.
York is exceptional, but even without proper
cycling facilities, it seems concern over the wisdom of encouraging
more people into seemingly hostile traffic is unfounded. The same
European report contained an estimate of the number of years of
life lost through cycling accidents compared to the number of years
gained through improved health and fitness due to regular cycling.
It concluded that even in the current environment, the benefits
gained were likely to outweigh the loss of life by a ratio of around
20:1.
In the next ten years, GPs will be prescribing
cycling and there will be adult cycle training schemes, available
through every regional health authority, equipping patients with
the confidence to ride away on their own. It already happens in
America. But if the authorities are really going to grasp the nettle
and put their money where the research is they have to be convinced
that motor dependency is bad news for more than just their parking
problem.
To coax people away from their cars requires
a radical alteration of behaviour on a par with that undertaken
by people fighting their drink, drug or eating problems. And undoubtedly
the best example of a success story is the 'smoking cessation' campaign
of the last fifteen years generated by none other than the health
authorities. They've done it once and cycling advocates are arguing
they can do it again.
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