Essay on CVD and exercise

Question 1

What percentage of deaths in 2014 in the UK were attributed to CVD

why are there more people living with the burden of CVD?

Answer 1

27%

better survival rates

Question 2

Outline the stages of atherosclerosis development

Answer 2

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

Question 3

who provided evidence that atherosclerosis starts early in life and what did they do to show this

Answer 3

Enos 1953
dissection of coronary arteries of Koran soldiers
77.3% had gross evidence of atherosclerosis despite being young and active

Question 4

who provided the first insight into the link between inactivity and CVD and what did he do

Answer 4

Morris 1949

compared rates CVD events in bus drivers vs conductors and found conductors had half the events of drivers

Question 5

describe the study by Morris et al 1980 and outline its main findings

Answer 5

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

Question 6

why did researchers move on to exploring the link between fitness and CVD

what critique to this method was offered

Answer 6

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

Question 7

what additional findings from the study on civil servents was published by Morris in 1990

Answer 7

protective effect of vigorous activity was independent of other risk factors for CVD

Question 8

What was the study by Barlow et al 2012

what were the findings

Answer 8

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

Question 9

what is the limitation of the study by Barlow et al 2012

Answer 9

only measured fitness at the start of the trial and assumed that it stayed the same throughout

Question 10

who published the aerobics centre longitudal study and in which year

Answer 10

Blair et al

1995

Question 11

what were the methods of the aerobics centre longitudal study

Answer 11

fitness established by a time on a maximal treadmill test

the fitness re tested 5 years later

Question 12

what were the results of note in the aerobics centre longitudal study

Answer 12

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

Question 13

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?

Answer 13

Katzmarzyk et al 2009

lots of participants, > 17 000
large age range of 18-90

54%
independent of PA

Question 14

who showed that exercise could offset an increased risk of CVD conferred by genetics?

what did they show

Answer 14

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

Question 15

who demonstated the links between total cholesterol and CHD mortality and between HDL and reduced CHD mortality

Answer 15

Simons 1986

Question 16

describe the study by La Porte et al 1983 and outline its findings

offer some critique of this work

Answer 16

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

Question 17

describe the study by Slentz et al 2007 and outline its findings

Answer 17

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

Question 18

what was the study by Kramsch et al 1981 and what did it find

Answer 18

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

Question 19

what type of evidence was presented by Currens and White 1961 and what did they show

Answer 19

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

Question 20

what three studies examine the link between BP and PA and the beneifts found and what did they show

Answer 20

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

Question 21

What did the study by Kokkinos et al 1996 show and what type of trial was it

Answer 21

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

Question 22

explain the study by Hambrecht et al 2000

Answer 22

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)

Question 23

what did the study by Gill et al 2004 show

Answer 23

was a RCT of middle aged men
exercise vs control

measured endothelial function the day after exercise
was 15% better in exercise group

Question 24

Harvard Alumni Health Study 1978 publication

Answer 24

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

Question 25

Harvard Alumni Health Study 1993 publication

Answer 25

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

Question 26

Berlin and Colditz 1990

Answer 26

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

Question 27

Epidemiology of CVD in the UK

Answer 27

Decreasing from around 1000 per 100000 to 200

British heart foundation 2015
Responsible for 27% of uk deaths in 2014

Question 28

Who published the proposed model for the process of atherosclerosis development

Answer 28

Ross 1999

Question 29

Meta analysis RCTs of exercise and hypertension

How much was lost in people with hypertension at baseline and who said it

Answer 29

Hagberg et al 2000

7.4 mmHg in systolic BP