Exercise as it relates to Disease/Can school-based physical activity interventions decrease CVD risk factors?

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“Action Schools! BC: A school-based physical activity intervention designed to decrease cardiovascular disease risk factors in children.” K.E.Reed et al. / Preventative Medicine 46(2008) 525-531

Action Schools! BC was designed by Healthy Schools BC, an initiative to build the capacity of schools to implement such interventions using a comprehensive school health approach. [1]

What is the background to this research?[edit]

Childhood obesity in Canada has become increasingly prevalent over the last couple of decades. An increase in body fatness is associated with an increase in risk factors for cardiovascular disease. Physical inactivity, genetic disposition and centralised body fat distribution all contribute to the increase risk. [2]

This research paper identified that Canadian school’s physical activity times are decreasing. Using the Action Schools! BC: intervention developed by Healthy Schools BC, created to increase physical activity times within schools, this research aimed to determine if it would improve cardiovascular disease risk profiles in year 4 and year 5 children.

Where is the research from?[edit]

This paper is from British Columbia, Canada. Researchers were from a variety of reputable universities and research institutions such as University of BC, Vancouver Coastal Health Research Centre and the Centre for Hip Health and Musculoskeletal Research. Having researchers from a variety of locations allows the research to be funded and recognised in the wider world.

What kind of research was this?[edit]

The research was a multi-component intervention study and more specifically a cluster randomised controlled school-based trial.

Multi-component: more than 1 methodological approaches

Intervention: the act of interfering with the outcome or course especially of a condition or process [3]

Cluster: groups of people, in this case schools

Randomised: appointed to either an intervention or control at random

Controlled: the schools were remotely randomised to either the control or intervention by a 3rd party.

It was not possible for the schools to be blinded to random assignment due to ethical reasons whilst dealing with 9-11year-old children.

What did the research involve?[edit]

268 boys and girls aged between 9-11 years of age from 8 schools were eligible for cardiovascular assessment and were randomly assigned (by school) to a usual practice (UP) group (n=2 schools/90 students) or intervention (INT) group (n=6 schools/178 students).

The main measurements that were assessed were:

  • Cardiovascular fitness- Leger’s 20m incremental shuttle run
  • Anthropometry- standing height and weight in light clothing which allowed BMI to be calculated as weight (kg)/height(m)2
  • Blood Pressure- lowest systolic and diastolic blood pressures were recorded following duplicate measurements after 5-10mins rest laying down
  • Physical Activity- modified version of the physical activity questionnaire for children

Measurements were taken at the beginning of phase 1 April-June 2003 and again during phase II (September 2003-May 2004). Changes between groups were recorded for the cardiovascular fitness, BMI and blood pressure.

Teachers of the INT schools were asked to deliver 15mins per day of additional PA, on top of their usual 2x40min PE classes per week. This added up to 75 extra minutes per week resulting in a combined total of 150 minutes per week of physical activity at school. This amount of physical activity for children sits well below both the Canadian and Australian guidelines of an accumulation of 60mins physical activity per day [4] [5]. The teachers were provided resources to support their action plan as well as a one-day training workshop.

Usual practice schools were asked to continue their regular physical activity routines of 2 x 40min PE classes per week. Again, far less than the Canadian and Australian standards for children’s physical activity.

What were the basic results?[edit]

Measurement All (n=237) Pre-UP (n=81) Pre-INT (n=156) Post-UP (adjusted score) Post-INT (adjusted score) % difference (unadjusted)
Cardiovascular fitness (laps) 29 (13.2) 32(4.3) 27 (12.5) 31(27,35) 37(36,39) +20.4%
SBP (mmHg) 104 (9.6) 104(10.5) 105(9.3) 108(106,110) 102(100,104) -5.7%
DBP (mmHg) 62(8.2) 60(8.2) 63(7.5) 65(62,68.6) 63(60,65) -3.8%
BMI (kg/m2) 18.9(3.6) 19.1(3.87) 18.8(3.5) 19.4(19.1,19.5) 19.2(4.0,4.2) -1.0%

Columns 2-4 are written as mean(standard deviation),

columns 5 and 6 show; score by group(final, 95% confidence interval).

% difference refers to how much higher or lower INT %change is compared with UP %change (INT %change – UP %change)

From these results, there is a significant difference is seen in the cardiovascular fitness with a 20.4% increase from the first test to the post intervention test. The only other significant result is the percentage difference of the systolic blood pressure(SBP); following intervention, SBP was reduced by 5.7%. Diastolic blood pressure and BMI had little-no change.

What conclusions can we take from this research?[edit]

There was a 20% increase in cardiovascular fitness through increasing physical activity during school time. Improved cardiovascular fitness is known to reduce cardiovascular disease risk factors in children. This not only shows that the AS!BC was an effective intervention, but also provides schools with an effective tool to increase physical activity time for children. Although the intervention doesn’t increase physical activity levels to the recommended guidelines, it provides a larger portion of the guidelines to be achieved during school hours, leaving less hours to be completed as extra-curricular activities around school and work commitments, taking the pressure off parents.

As the research is based solely in BC, Canada, its applicability to the rest of the world may not be relevant, however to the rest of Canada and countries of similar health statistics to Canada, such as Australia, this research could apply nicely.

More research does need to be done in this area, especially in this day and age where countries are becoming fatter, cardiovascular disease risks are increasing, and this is starting at much earlier ages. Habits start from an early age, so if we can educate our children and get them into these healthy physical activity habits early, hopefully obesity levels, cardiovascular disease risk factors as well as a range of other things will decrease.

Practical advice[edit]

The research paper has provided strong evidence that school physical activity intervention models increase children’s cardiovascular fitness and thus decrease prevalence of cardiovascular disease risk factors. Asking questions of your schools, or your children’s/grandchildren’s/niece’s/nephews schools as to what type of physical activity they do as well as how much and how its per
formed could be pivotal to your children’s health and development of healthy habits as they age.

Initiatives such as the NSW Premiers Sporting Challenge used by NSW public schools to encourage all students to be more active more often are a great way to increase physical activity amongst school aged children

Further information/resources[edit]

AS!BC resources: https://healthyschoolsbc.ca/healthy-schools-bc-resources/action-schools-bc-resources/

Canadian physical activity guidelines http://csep.ca/CMFiles/Guidelines/CSEP_PAGuidelines_0-65plus_en.pdf

Australian physical activity guidelines http://www.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-phys-act-guidelines#apa512

Legers 20m Shuttle Run information and instructions: https://www.topendsports.com/testing/tests/20mshuttle.htm


  1. Healthyschoolsbc.ca. (2018). Healthy Schools BC. [online] Available at: https://healthyschoolsbc.ca/about/healthy-schools-bc/
  2. Ball, G. and McCargar, L. (2003). Childhood Obesity in Canada: A Review of Prevalence Estimates and Risk Factors for Cardiovascular Diseases and Type 2 Diabetes. Canadian Journal of Applied Physiology, 28(1), pp.117-140
  3. Merriam-webster.com. (2018). Definition of INTERVENTION. [online] Available at: https://www.merriam-webster.com/dictionary/intervention.
  4. Health.gov.au. (2018). Department of Health | Australia's Physical Activity and Sedentary Behaviour Guidelines . [online] Available at: http://www.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-phys-act-guidelines#apa512
  5. Csep.ca. (2018). [online] Available at: http://csep.ca/CMFiles/Guidelines/CSEP_PAGuidelines_0-65plus_en.pdf