# Exercise as it relates to Disease/Reducing the risk of CVD with daily physical activity in school children

The Paper analyzed was "Effects of a 2-year school-based daily physical activity intervention on cardiovascular disease risk factors: the Sogndal school-intervention study".
Analyzed by student u3119178

## BACKGROUND INFORMATION TO THE STUDY
### What is Cardiovascular Disease?

“Cardiovascular disease (CVD) is a collective term for diseases of the heart and blood vessels.” The diseases classified under CVD include:
* Coronary heart disease
* Heart failure
* Cardiomyopathy
* Congenital heart disease
* Peripheral vascular disease
* Stroke

### Why is it an issue?

CVD is a critical concern within the Australian health system. In 2012, 43,946 people died as a result of CVD, making it the leading cause of death within Australia. It also came out in front in regards to expenditure, an estimated $7,605 Million was spent on CVD in 08-09. This is a definite cause of concern, particularly when CVD is a highly preventable disease. CVD originates from risk factors, in which many can be controlled, modified, treated or prevented. Therefore making it an important issue to investigate.

### Why School Children?

CVD mainly affects adults in their forties and onwards. However, research shows that atherosclerosis can begin during childhood. With CVD being a highly preventable disease it raises questions as to wether prevention strategies should begin earlier. The researchers of the current study aimed to determine wether an intervention within 9-year-old school children would help to reduce their CVD risk profile. Furthermore, developing healthy habits for them now is important, to help prevent later onset of CVD. School children were considered a good cohort for this study because of:
a) Percentage of time spent within the school environment, allows for an aggressive intervention which can be conducted for long periods of time
b) Large environment in means of accessing a large population from all backgrounds
c) Clustering of risk factors in school children is seen to progress from childhood to adulthood

## THE STUDY
### Where is the research from?

The research was collected from two different schools in two different cities approx. 100 km apart; Sogndal (intervention site) and Forde (control site) in rural Western Norway. Researchers in differing areas including: education and sport, sports science and clinical biomechanics, sports medicine and childhood health conducted the study. The paper was published in the Scandinavian Journal of Medicine and Science in Sports. Which is a peer reviewed academic journal.

### What type of study was this?

This study was a controlled non-randomized design consisting of a physical activity intervention. “The aim of the study was to investigate the effect of a two-year school-based physical activity intervention in nine-year old school children on CVD risk factors”. Utilising a non randomized design, could be considered a limitation and bias, however other considerations were taken to minimise the effect of this.

### What did the study involve?

This study had 174 fourth grade school children (born either 199 or 96) who successfully completed both the baseline and post intervention measurements for the two-year intervention. Measurements of CVD risk factors were taken both pre and post intervention. These measurements included:
* Body mass index (BMI)
* Homeostasis model assessment
* Waist circumference
* Triglycerides
* Systolic and diastolic blood pressure
* Total cholesterol to high density lipoprotein ratio
* Fitness (VO2peak)
They were then split into two cohorts, 92 children were allocated to the intervention cohort (Sogndal school) and 82 to the control cohort (Forde school). The intervention group conducted 60 mins of physical activity lessons each school day. These lessons were planned and conducted by expert Physical Education (PE) teachers. They consisted of moderate to vigorous activity (approx. only 15 mins at a vigorous level), with time spent explaining activities and also conducting light intensity exercises for warm up and cool down. Lessons included a variety of activates to maintain interest and keep the lessons fun and enjoyable. The control group were allocated the prescribed amount of exercise stated within the curriculum; 2 x 45 min PE classes per week.

### Results

From the results table below there is a significant positive correlation between a physical activity intervention and 5 of the risk factors associated with CVD.

#### Table 1

| CVD risk factors | Final P value (comparison of intervention to control group) |
| Systolic Blood Pressure (mmHg) | 0.003 |
| Diastolic Blood Pressure (mmHg) | 0.002 |
| Peak Oxygen uptake (mL/kg/min) | <0.001 |
| Triglycerides (mmol/L) | 0.003 |
| Total Cholestrol: High Density Lipoprotin ratio | 0.011 |
| Waist Circumference (cm) | 0.943 |
| Body Mass Index (BMI) | 0.530 |
| Homeostasis Model Assessment | 0.058 |

## DISCUSSION
### Conclusions

The study concluded that physical activity could be used as a tool to reduce CVD risk profiles in a children’s population. They stated however that the Physical activity would have to be of a substantial amount and should be implemented by expert PE teachers.

### Practical advice

From the study it is evident that physical activity levels can be critical to preventing CVD and its associated risk factors. Although it is also clear that it would be quite difficult to implement an extra 60min class into the school curriculum. In addition to this however, school is an environment in which children and adolescents spend majority of their time, from ages 6–16. Therefore a practical suggestion would be to add pre and post school care, similar to after care, in which exercise programs could be run. It would also be suggested that an overall standardized curriculum be written which is easily reproducible.

### Pros and Cons of the study
#### Table 2

| Positives | Negatives |
| Length of time the study was conducted Cohort size Reasonably even numbers of male and female participants Reasonably even numbers of control vs. intervention Extensive tests which were conducted by the same people pre and post intervention Expert PE teachers were used to ensure intervention was done correctly and appropriate for children. One of the first studies in this area or field to be conducted for such a long period of time with such a large sample size increasing its validity and reliability. | Non randomized study Although populations in both cities were similar there could be differing environmental factors etc. BMI used as a measure, yes it is a good general indicator for comparison in populations however assessments such as skinfolds may have been a better indicator for body composition in this particular study The study didn’t outline specific programs that were conducted for the intervention, only a brief overview was given as to how the classes were set out. If it were to be successfully implemented as a strategy to prevent CVD later in life it would be expensive to implement. Also: training for PE teachers would have to change to ensure classes were safe to conduct and the School curriculum is alreaady quite extensive, finding additional space could be difficult |

### Overall

To conclude this study shows that physical activity could be an effective positive intervention for children to reduce their CVD risk profile but to also build healthy habits for their future. Thus helping to prevent and minimise incidence of CVD in a future setting. Overall the researchers have provided a strong study that has presented useful results and information surrounding physical activity and cardiovascular disease risk factors in children.

### Further reading

For further information on CVD risk factors and the benefits of physical activity please read the following:
* Physical inactivity and cardiovascular disease: http://www.world-heart-federation.org/cardiovascular-health/cardiovascular-disease-risk-factors/physical-inactivity/
* Clustering of Cardiovascular risk factors in Children: http://www.ncbi.nlm.nih.gov/pubmed/18278634
* Physical activity and Cardiovascular risk factors in Children: http://www98.griffith.edu.au/dspace/bitstream/handle/10072/45326/77742_1.pdf;jsessionid=CAA5763BE52E266EE3187DA40C32C0D5?sequence=1
* overview of cardiovascular disease as an issue: https://www.youtube.com/watch?v=jxJ1EJz3WZ8

## References

* 1 2 3 Australian Government, Department of Health. 2015. Cardiovascular Disease. 1-4. https://www.health.gov.au/internet/main/publishing.nsf/Content/chronic-cardio
* ↑ Australian Government, Australian Institute of Health and Welfare. 2014. Cardiovascular disease top Australian health care spending. 1-2. http://www.aihw.gov.au/media-release-detail/?id=60129546452
* ↑ World Heart Federation. (unknown date). Cardiovascular disease risk factors. 1-4. http://www.world-heart-federation.org/press/fact-sheets/cardiovascular-disease-risk-factors/
* 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 G, K Resaland. S, A Anderssen. I, M Holme. A Mamen. L, B Andersen. Effects of a 2-year school base daily physical activity intervention on cardiovascular disease risk factors: the Sogndal school-itervention study. 2011. Scandinavian Journal of Medicine and Science in Sports. 21. e122-e131.
* 1 2 3 4 G, K Resaland. A Mamen. C Boreham. S, A Anderssen. L, B Andersen. Cardiovascular risk factor clustering and its association with fitness in nine-year old rural Norwegian children. 2009. Scandinavian Journal of Medicine and Science in sports.
* 1 2 3 G, K Resaland. Cardiorespiratory fitness and cardiovascular disease risk factors in children: effects ofa two-year school based daily physical activity intervention: the Sogndal school-intervention study. Doctoral Thesis. 2010. HiSF Brage. 1-2. http://hdl.handle.net/11250/150429