# Exercise as it relates to Disease/Aerobic exercise in Down Syndrome
## Background
### What is Down syndrome

Down syndrome (DS) is a genetic disease caused by a third copy of chromosome 21 (trisomy 21). Usually identified soon after conception, the increased protein expression of genes on chromosome 21 will cause a cascade effect on a child’s developing brain, leading to impairments in the development of language and speech, cognitive development, and auditory short-term memory.
In addition to cognitive impairments, DS also inhibits the development of certain motor movement patterns, due to people with DS typically having a smaller cerebellum, cognitive delays, cardiac problems, and a less efficient nervous system., all of which contribute to the decrease in motor movement efficiency when compared to those without DS. Areas most commonly affected are: decision making, response selection and action planning, all of which will ultimately lead to poorer motor performance, which is further enhanced by an impaired cognitive function.
Health problems are also very common in people with DS, with a high percentage of people with DS suffering from cardiac problems and obesity. Research supports a relationship between mental disabilities and some anthropometrical parameters such as body mass index, exercise and disability status. This is due to a restricted physical work capacity(due to reduced heart rate response to exercise), poor coordination, and reduced peak oxygen uptake.

### Prevalence

DS occurs in roughly 1 in 800 births, and is the most commonly identified cause of mental disabilities. As of October 2013, there was over 13,000 people living in Australia diagnosed with DS.

## Aerobic exercise
### What is aerobic exercise

Aerobic exercise is a discipline of exercise that increases cardiovascular function. In clinical settings, aerobic exercise is prescribed to prevent or treat cardiovascular disease and improve quality of life. Some popular and effective forms of aerobic exercise are:
* Walking
* Running
* Swimming
* Aquarobics
* Cycling
* Rowing
* Boxing
* Dancing

### Recommendations

New physical activity guidelines recommend that individuals accumulate between 150 and 300 hours a week of moderate intensity exercise, and 75 to 150 minutes a week of vigorous physical activity. The guidelines also recommend doing resistance training two days a week, and remaining active for most days of the week. It is also recommended to avoiding prolonged time 'being sedentary' such as sitting, driving, and laying down.

### Morbidity as it's influenced by sedentary behaviour, and diseases related to Down syndrome

Certain aspects of Down syndrome contribute to a high amount of time spend being sedentary. Studies have generally fallen short of establishing a direct link between DS and a high morbidity rate, However research proposes a number of factors that may be responsible for contributing to diseases associated with low levels of fitness.
Factors that contribute to low levels of fitness:
* High amount of time being sedentary
* Poor motor function
* Muscle weakness
* Heart defects
* Lower than normal peak oxygen uptake
* Circulatory abnormalities
* Low maximal heart rates
* And pulmonary abnormalities.

### Why aerobic exercise is necessary for people with Down Syndrome

There is strong evidence to support the theory that aerobic activity can help to prevent chronic diseases, such as Cardiovascular heart disease, diabetes, osteoporosis, and metabolic syndrome. Given the strong relationship between chronic diseases and DS, it can be deduced that aerobic activity can be effective in reducing the risk of these diseases in people with DS. it is therefore vital to ensure people affected with DS follow the physical activity guidelines previously mentioned. Studies published that walking briskly for 3 hours a week, or vigorously for 1.5 hours a week, can reduce the chances of coronary heart disease by up to 40%. Research indicates that exercise reduces the chances of osteoporosis related bone fractures by almost 50%. There is also sufficient evidence that aerobic exercise alone has a positive influence on body fat percentage, and BMI, as well as increasing cardiovascular function, and motor/cognitive function.

## References

* 1 2 Chapman, R., Hesketh, L. ‘Behavioural phenotype of individuals with Down syndrome’ (2000) 84 – 95.
* 1 2 3 Angulo-Barroso, R., Burghardt, A., Lloyd, M., Ulrich, D., ‘Physical activity in infants with Down syndrome receiving a treadmill intervention’ (2008) 255 – 269.
* ↑ Jover, M., Ayuon, C., Berton, C., Carlier, M. ‘Development of motor planning for dexterity tasks in trisomy 21’ (2014) 1562 – 1570
* ↑ McKay, S., Angulo-Barroso, R,M. ‘Longitudinal assessment of leg motor activity and sleep patterns in infants with and without Down syndrome’ (2005) 153 – 168
* 1 2 Ordonez, F., Rosety, M., Rodriguez, M. ‘Influence of 12-week exercise training on fat mass percentage in adolescents with Down syndrome’ (2006); 12(10) 416 - 419
* ↑ http://www.downsyndrome.org.au/down_syndrome_population_statistics.html#_edn5
* ↑ Singh, A., Duncan, R., Neva, J., Staines, R. ‘Aerobic exercise modulates intracortical inhibition and facilitation in a nonexercised upper limb muscle’ (2014)
* ↑ http://www.bupa.com.au/health-and-wellness/health-information/az-health-information/types-of-aerobic-exercise Accessed on 29/09/2014(
* ↑ http://www.health.gov.au/internet/main/publishing.nsf/Content/health-pubhlth-strateg-phys-act-guidelines
* 1 2 Dodd, K., Shields, N. ‘A systematic review of the outcomes of cardiovascular exercise programs for people with Down syndrome’ (2005) 2051 - 8
* ↑ Manson, J., Hu, F., Et al.. ‘A Prospective Study of Walking as Compared with Vigorous Exercise in the Prevention of Coronary Heart Disease in Women’ (1999) 650 - 658
* ↑ Davidson, R., Grant, S., 'Is walking sufficient exercise for health?' (2012) 369 - 373
* ↑ Andersen, R., Wadden, T., Barlett, S., Zemel, B., Verde, T., Franckowiak, S. 'Effects of lifestyle activity vs structured aerobic exercise in obese women' (1999) 335 - 340
* ↑ Blumenthal, J., Emery, C. et al. 'Cardiovascular and behavioural effects of aerobic exercise training in healthy older men and women' (1988)
* ↑ Colcombe, S., Kramer, A. 'Fitness effects on the cognitive function of older adults' (2003) (2) 125 - 130