Week 9 children and adolescents Flashcards
Why study young people?
Children are not ‘mini adults’ - growth, maturation and development can influence physiological responses to exercise
Origin of many chronic diseases lies in childhood
Critical period to establish healthy attitudes / behaviours
Summarise the relationship between PA and health across the life course?
Strong evidence suggests regular exercise is associated with a lower risk of cardiac disease and premature mortality
Many disease outcomes are thought have physiological processes that start during childhood
So if we promote PA in early life this may have favourable effects in terms of delaying adverse health outcomes in later life
What are the current PA recommendations for young people?
60mins MVPA daily
Should include some PA that promotes muscle and bone strength
Should reduce sedentary time
Are young people meeting the PA guidelines?
In 2015 (uk) 23% of boys and 20% of girls aged 5-15yrs met the PA guidelines
What did Cooper et al (2015) find about young people meeting the PA guidelines?
On average, 9% of boys and 2% of girls aged 5-17yrs met the PA guidelines.
Summarise the longitudinal patterns of objectively measured PA
Boys more active than girls
Overweight individuals less active
PA levels decline through childhood into adolescence
What is a challenge of working with this young people population?
It can be difficult to accurately measure their PA
Typically engage in activities that are stop start in nature
Becoming easier to measure recently with use of accelerometers
Summarise the progression of atherosclerosis
Build up of fatty material to the arterial wall resulting in narrowed blood vessel
Fatty streaks (first lesion of atherosclerosis) are known to appear in both the aorta and coronary wall during the first and second decades of life
These manifestations develop quickly in terms of number and severity during adolescence into young adulthood.
What were the key findings of pooled data from 14 studies looking at MVPA, sedentary time and cardiometabolic risk factors in young people?
- risk factors looked at - waist circumference, SBP, fasting triglycerides, high-density lipoprotein cholesterol and insulin.
Time spent in MVPA was associated with all cardiometabolic outcomes independent of sex, age, monitor wear time, time spent sedentary and waist circumference
Sedentary time was not associated with any outcome independent of time in MVPA
Higher levels of PA in childhood is associated with better cardiovascular health in young adulthood.
What is flow mediated dilation?
The ability of the vessel to vasodilate in response to an increase in blood flow following a period of occlusion.
What can flow mediate dilation be used as an indicator of?
Used as an indicator of endothelial function
Can also be used as a surrogate indicator of atherosclerosis
What were the key results of the study by Mayer et al (2006) looking at improvement of early vascular changes and CV risk factors in children with obesity after a 6 month exercise programme?
Marked improvement in flow mediated dilation so suggests exercise may promote an improvement in endothelial function
Marked reductions in both systolic blood pressure and LDL cholesterol
What are the physiological mechanisms that may explain an improvement in flow mediated dilation / endothelial function after an exercise programme?
Nitric oxide-induced vasodilation (increase in endothelial nitric oxide synthase)
Arterial remodelling (most likely a reduction in the thickness of the arterial wall) will increase cross sectional area of the lumen and therefore promote vasodilation.
What are the physiological mechanisms that may explain the reduction in SBP after an exercise programme?
Reduction in systemic vascular resistance, probably mediated through an increase in endothelial independent vasodilation.
Structural changes may also increase the cross sectional area of the vessel which will increase the amount of resistance to blood flow and therefore reduce arterial BP.
What is the current trends in the prevalence of overweight and obesity in children?
In 2018/2019, 22.6% in reception and 34.3% in year 6 were measured as overweight or obese.
However, particularly in countries with higher socio-economic status, there is some evidence that childhood obesity rates are starting to plateau (although still very high).
Summarise the observational evidence about the relationship between PA and body fat in young people. Is there reverse causality, could it be that excess body fat predisposes children to be physically inactive?
Metcalf et al (2009) found that physical inactivity may be a consequence rather than a cause of excess body fat.
However, must note it is easier to measure body fat in a lab than it is to measure behaviour (in terms of PA)
More research still needs to be done in this area, but what does a study by Adab et al (2018) suggest about the efficacy of PA interventions for the prevention of obesity?
Tried to encourage children to engage in an additional 30 mins of PA and ran family based dietary workshops including signposting for PA.
Found the intervention had no effect on BMI and childhood obesity compared to the control condition.
What has been concluded about the efficacy of PA interventions for the treatment of obesity?
Despite the low quality of evidence, multidisciplinary interventions combining PA, diet and behaviour change promote overall small but important reductions in BMI, BMI2 score, and body mass in young people.
What were the key findings of the study by Lee et al (2012) looking at PA as treatment for obesity?
Both aerobic and resistance training interventions resulted in significant reductions in body weight, BMI and waist circumference as well as increased skeletal muscle mass.
Also caused significant reductions in visceral adipose tissue and liver fat.
Summarise the prevalence of T1 and T11 diabetes in young people?
T1 general diagnosed earlier in life however there is now an increase in prevalence of T11 in young people
In young people there is evidence to suggest that the decline in B cell function (T11) is faster and also linked with increased development of diabetes related complications.
Why might it be difficult to interpret findings on insulin resistance in adolescents?
There are natural fluctuations in insulin resistance throughout puberty
What were the key findings in Metcalf’s et al (2015) study about PA and mid-adolescent peak in insulin resistance?
Peak in insulin resistance at 12-13yrs was 17% lower in individuals with higher levels of PA. This difference diminished over the subsequent three years.
Suggests PA may be effective in reducing the normal puberty related peak in insulin resistance
What did Lee et al (2012) suggest were the benefits of resistance rather than aerobic training)
*still get the benefits with aerobic, just more so with resistance
Greater increase in insulin sensitivity
Increased skeletal muscle (likely to facilitate insulin mediated glucose removal)
Increased metabolism and delivery of glucose
Increased expression of GLUT4
Increased mitochondrial size and content
More research is needed, but what did a study by diabetes care (2013) suggest about treatment options for T11D in young people?
Metformin combined with lifestyle intervention was no more effective in preventing loss of glycaemic control than metformin alone and neither of these had an effect on insulin sensitivity or B cell function over a 4yr follow up.
