Essay on CVD and exercise Flashcards
What percentage of deaths in 2014 in the UK were attributed to CVD
why are there more people living with the burden of CVD?
27%
better survival rates
Outline the stages of atherosclerosis development
1) endothelium damaged leading to increase in permiability so LDL enters the vessel wall which triggers an inflammatory process
2) macrophages ingest the LDL and form foam cells
3) foam cells accumilate to form a fatty streak which then develops into a plaque
4) plaque continues to grow until it occludes part of the artery
plaque is also increasingly succeptible to rupture
who provided evidence that atherosclerosis starts early in life and what did they do to show this
Enos 1953
dissection of coronary arteries of Koran soldiers
77.3% had gross evidence of atherosclerosis despite being young and active
who provided the first insight into the link between inactivity and CVD and what did he do
Morris 1949
compared rates CVD events in bus drivers vs conductors and found conductors had half the events of drivers
describe the study by Morris et al 1980 and outline its main findings
9000 civil servants who mainly had desk based jobs
healthy middle aged men followed for around 10 years
9% reported participation in vigorous sport/doing considerable amounts of cycling/walking at fast pace
the incidence of fatal and non fatal CHD in this group was half of that in those not in the group
Also more vigorous sport = lower standardised rate of CHD
showing a dose response relationship
this relationship was not seen for increasing amounts of non-vigorous sport
why did researchers move on to exploring the link between fitness and CVD
what critique to this method was offered
fitness is more of an objective measure
self report of level of PA is likely to lead to misclassification
fitness is determined by genetics, but has been shown to be mostly determined by the environment
what additional findings from the study on civil servents was published by Morris in 1990
protective effect of vigorous activity was independent of other risk factors for CVD
What was the study by Barlow et al 2012
what were the findings
study of over 11 000 healthy men
separated them into quintiles of physical fitness
found incremental decline in risk of CVD mortality with increasing cardioresp fitness
71% decline in risk of CVD mortality between highest and lowest fit
1 MET increase in cardioresp fitness lead to 18% reduction in CVD deaths after adjustment for confounders
what is the limitation of the study by Barlow et al 2012
only measured fitness at the start of the trial and assumed that it stayed the same throughout
who published the aerobics centre longitudal study and in which year
Blair et al
1995
what were the methods of the aerobics centre longitudal study
fitness established by a time on a maximal treadmill test
the fitness re tested 5 years later
what were the results of note in the aerobics centre longitudal study
those who were unfit and then fit had a 52% lower relative risk of CVD mortality than those who were unfit on both tests
relative risk of low fitness was higher than the relative risk of smoking, hypertension and high cholesterol
who published data showing a dose response relationship between sitting time and CVD mortality
why could this be considered a strong study design
what was the difference in relative risk of CVD mortality between those sitting almost all of the time and those sitting almost none of the time?
Katzmarzyk et al 2009
lots of participants, > 17 000
large age range of 18-90
54%
independent of PA
who showed that exercise could offset an increased risk of CVD conferred by genetics?
what did they show
Khera et al 2016
high genetic risk had a 75% higher risk of coronary event than low
but a favourable lifestyle was able to reduce the rate coronary events over a 10 year period by around 50%
people with high genetic risk but the most favourable lifestyle had a lower risk of a coronary event than those with the least favourable lifestyle in the low and intermediate genetic risk groups
who demonstated the links between total cholesterol and CHD mortality and between HDL and reduced CHD mortality
Simons 1986
describe the study by La Porte et al 1983 and outline its findings
offer some critique of this work
measured the HDL levels of variety of people ranging from long distance runners to sedentary people to those with a spinal cord injury
as level of activity decreased the level of HDL decreased
HDL levels of sedentary people was still in the healthy range
only cross sectional data so can only show an association
describe the study by Slentz et al 2007 and outline its findings
RCT over 6 months of 240 middle aged men
control
low amount, moderate intensity
low amount, high intensity
high amount, high intensity
24hrs post last session:
decreased VLDL for all exercise groups
increase in HDL was greater for increasing amount or intensity of exercise
vigorous intensity reduced LDL whereas moderate intensity just attenuated the increase seen in controls
15 days post last session:
benefits had began to become attenuated
vigorous groups still had a significant increase in HDL
decrease in LDL had disapeared
what was the study by Kramsch et al 1981 and what did it find
RCT carried out on monkeys bc of ethics
normal, normal diet
no exercise, atherogenic diet
exercise, atherogenic diet
atherogenic diet group had increase in; total cholesterol, LDL and VLDL
however coronary artery narrowing was 10% in the exercise group vs 30-40% in the non-exercise group
exercise gives protection against atherosclerosis development
what type of evidence was presented by Currens and White 1961 and what did they show
A case study of the post mortem of someone who had ran over 50 marathons
his coronary arteries had a diameter 2-3 times larger than predicted and had very little evidence of atherosclerosis
what three studies examine the link between BP and PA and the beneifts found and what did they show
Truswell et al 1972:
Bushman tribes of Botswana did not have an increase in systolic BP seen with Londoners over their lifetime
Blair et al 1995:
men in least fit quintlie were 52% more likely to develop hypertension than those in the most fit
Pescatello et al 2004:
reduction of 2 mmHg in SBP = 9% decreased CHD risk and 14% decreased stroke risk
What did the study by Kokkinos et al 1996 show and what type of trial was it
RCT:
hypertension medication only vs meds + exercise
In African American men bc of high prevelence of hypertension in this population
after 16 and 32 weeks addition of exercise showed significant reductions in DBP and there was also a significant reduction in the amount of meds these people were taking
explain the study by Hambrecht et al 2000
RCT of patients who had endothelial dysfunction
exercise vs non-exercise
Post intervention the exercise group showed less vasoconstiction in response to Ach dose
(vasoconstriction in response to Ach usually only happens in pathology)
what did the study by Gill et al 2004 show
was a RCT of middle aged men
exercise vs control
measured endothelial function the day after exercise
was 15% better in exercise group
Harvard Alumni Health Study 1978 publication
Paffenbarger
PA habits of males who had graduated between 1916 and 1950
asked about current participation in sport and participation in sport whilst at Harvard
Findings:
relative risk of MI was inversly related to energy expenditure
men who had participated in sport at Harvard did not have reduced risk unless they continued to be physically active
Harvard Alumni Health Study 1993 publication
incorperated a 3rd questionnaire in 1977
findings:
previously sedentary people who increased their activity had a 17% lower risk of death from CHD than those who remained sednetary
the decreased risk became 44% if they had taken up vigorous activity.
this benefit is similar to the benefit seen if quitting smoking
Berlin and Colditz 1990
meta analysis of trials in this area
2/3 found sig benefit of exercise
better studies more likely to report inverse relationship
no study found increased risk
risk associated with inactivity was similar to risk associated with high cholesterol, hypertension and smoking
Epidemiology of CVD in the UK
Decreasing from around 1000 per 100000 to 200
British heart foundation 2015
Responsible for 27% of uk deaths in 2014
Who published the proposed model for the process of atherosclerosis development
Ross 1999
Meta analysis RCTs of exercise and hypertension
How much was lost in people with hypertension at baseline and who said it
Hagberg et al 2000
7.4 mmHg in systolic BP
