The Weight of the Nation: Physical inactivity, and
some steps forward
Grant Schofield Ph.D.
Auckland University of Technology
The Weight of the Nation
The increasing prevalence of overweight and obesity in
the population is a serious problem with serious long-term repercussions for the
NZ health system. Predictions for increases in lifestyle-related diseases and
health-care costs related to these diseases are alarming. Recent debate around
overweight and obesity has centred on childhood obesity. However, it is not just
our youth who are at risk. Adults are likely leading the way.
Positive energy balance
There is only one explanation for the rise in the
prevalence of overweight and obesity. It is simply a matter of energy balance.
Over the population we are consuming more energy than we are expending. So the
solution to this simple problem appears simple. Consume less energy or expend
more energy. Which is the best solution? What has happened in recent times –
is the positive energy balance due to increases in food consumption especially
dietary fat? Or are we simply expending less energy than in the past?
The research evidence is not available in New
Zealand. We simply do not have the data to make any definitive conclusions. However,
looking at data from the UK and USA the answer appears to be that sloth rather
than gluttony is the culprit. Data from the British National Health survey show
that energy intake in Britain has declined slightly as obesity rates have risen
rapidly. The implication is that levels of physical activity have declined even
faster (Prentice & Jebb, 1995). US data show similar effect. Heini and Weinsier
(1997) demonstrated that aaverage caloric intake decreased 4% in the American
diet from 1976 – 1991 and that average fat intake dropped by 11% during the
same period. Paradoxically, the percentage of population involved in regular exercise
remained constant and the prevalence of overweight increased from 31% from 1976
to 1991. These studies point to a decline in activity as a primary factor in population
weight increases. The US data suggest that it may be the day-to-day or “incidental”
activity not exercise which is mainly responsible for the net positive energy
balance.
Of course, we could also eat better and this should
not be disregarded as important in public health campaigns. However, getting adults
and youth moving again is an important public health priority. It also deserves
a coordinated approach from the health service providers and sport and recreation
providers (e.g., Sport and Recreation NZ, regional sports trusts, and local councils)
Some positive steps forward for New Zealand….
Surveillance
Before considering how we might solve any lifestyle
health problems in NZ we first need to understand the nature and extent of the
problem. Little cross-sectional population data are available in any NZ age group
simultaneously examining body fatness, dietary habits, and physical activity.
Much of the data that does exist has not been collected well-validated and reliable
measures. This is especially so in physical activity measurement. In primary aged
children objective monitoring of physical activity is a necessity because self-report
and proxy report data have been shown to be unreliable. Little objective monitoring
of physical activity in this group has occurred in NZ. For our adolescent population
we have little understanding of either overall activity levels or important changes
that occur across adolescence. In adults we have a clearer picture of inactivity
but the self-report measure used has not been objectively validated giving the
data questionable value. Sport and Recreation NZ are moving on some of these problems
and are presently validating a new adult physical activity survey for future surveillance.
In any case, we are someway behind most other western
countries in understanding our national lifestyle and its relationship to chronic
disease. We must also consider the range of ethnicity represented in the New Zealand
population. Pakeha, Maori, Pacific Island peoples, and Asians have different lean
muscle and body fatness characteristics which need to be considered in population
measurement of body fatness. The different ethnic groups may also have differential
contributions to the energy balance problem. For example, it is possible that
Pakehas and Asians are in energy balance by and large because of reduced activity
whilst Maori and Pacific peoples are more active but as a group have a higher
energy intake. These relationships are not known and have important implications
for the development of health promotion interventions to prevent lifestyle disease.
Interventions
The major physical activity health promotion intervention
in NZ in recent times has been the Push-Play campaign first developed by the Hillary
Commission. Although this programme has had some success in raising awareness
of the benefits of an active lifestyle, it has not been able to provide the support
or advocacy necessary for widespread policy, environmental, organisational, and
individual behaviour change to promote such a lifestyle. Such an approach is likely
needed to reverse current trends.
Overseas experiences – 10.000 Steps
So what of overseas experiences in physical activity
health promotion that might help us understand and structure such a multilevel
approach? I have been fortunate to have been working with a team of public health
researchers and workers over the past few years in a project called “10,000
Steps Rockhampton”. The project is a two-year $800,000 community-wide intervention
in the regional city of Rockhampton on Queensland’s Tropic of Capricorn funding
the Queensland Health’s Health Promoting Queensland Unit. The Rockhampton
community was chosen as a large regional centre that evidences both socio-economic
and health disadvantage reflected in all parts of regional Australia. The principle
difference in this health promotion campaign compared with others, and one of
the unique features of the project, is that the message is more specific, promoting
both the mode (walking) and volume (10,000 Steps) of activity. The specific objectives
of the programme are to create sustainable strategies for promoting physical activity
at the local level by:
a) Raising community awareness of the health benefits
of moderate physical activity;
b) Strengthening the capacity of general practitioners and other health professionals
to promote physical activity;
c) Strengthening the capacity of the community to provide improved opportunities,
social support, policies and environments for physical activity;
d) Strengthening the capacity of individuals to be more active, by addressing
modifiable individual, social and environmental determinants of (in)activity.
Although this intervention has been multilevel
and well structured in terms of the Ottawa Charter principles of health promotion
I wish to concentrate on the activity prescripion of “10,000 Steps”
as a health promotion message. Rockhampton residents were encouraged to monitor
their activity using pedometers. These were available through several sources
including outright purchase, GP or other health professional loan scheme, and
library loan scheme. In all cases pedometers were supplied with support materials,
follow-up materials, and a daily-guided log to manage sensible changes to daily
activity.
Pedometers and counting steps
What is a pedometer?
A pedometer is a small electronic device mounted
on the hip. It uses a horizontal pendulum mechanism to count steps. The latest
Japanese models, in particular the Yamax Digiwalker are very accurate and have
a well-documented reliability and validity. Pedometers are very useful for both
objectively measuring physical activity and as a monitoring and motivational tool
in physical activity health promotion.
The goal of 10,000 steps per day to achieve health-benefits
from physical activity is related to recent activity guidelines. The US Surgeon
General’s report recommends “at least 30 minutes of moderate activity
on most, if not all days of the week” as the duration and frequency necessary
for health benefits. The 10,000 Steps goal is a different to this because it counts
all activity across the day. However, for the average “low active” person
adding an extra 30 minutes of walking would usually put them around the 10,000-step
mark. The accumulation of movement over the day is useful in breaking through
barriers such as “lack of time” and “I’m not the not the sporty
type”. Because activity can be accumulated a shift in mindset in seeing activity
as an opportunity not an inconvenience can be instantly rewarded with extra-recorded
steps. In Rockhampton the pedometer has been an instant success both as an awareness
raiser and a motivator for individuals. Importantly, it may be effective in promoting
exactly the sort of activity that we have dispensed with in recent decades.
Conclusion
It is likely that the positive energy balance resulting
in increasing prevalence of overweight and obesity can be overcome wit increased
lifestyle activity in the community. One approach that may work well in NZ is
the 10,000 Steps message. This message may be more effective in promoting incidental
activity and therefore effectively address daily energy balance issues.
Community interventions must be multilevel and
move beyond a simple media message approach to provide a basis for sustainable
behaviour change. Of course, implementing a comprehensive community-based model
is costly. Recent burden of disease data would suggest that we cannot afford not
to address lifestyle disease comprehensively. Physical activity health promotion
is a public health “smart buy” right now in NZ. First through we need
a clear picture of the relationship between nutrition, physical activity, and
fatness in New Zealand across all age groups and ethnicities. Without a clear
picture we have no way of understanding the problem or monitoring the success
of any such intervention.