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June 16, 2013 1Physical Activity&Cardiovascular DiseasesShreya Sharma37S.Y.B.A
June 16, 2013 2Introduction• Physical activity is any form of movement that works muscles anduses more energy than when resting.Eg :- Walking, running, dancing, swimming, yoga, gardening..• Lack of physical activity is clearly shown to be a risk factor forcoronary heart disease (CHD) & coronary arteries diseases(CAD).
June 16, 2013 3• He established the importance of physical activity in preventingCVD.• Examined the onset of coronary artery disease in 31000 maletransport workers aged 35 to 65 years .• Main objective - “seek for relations between the kind of work men doand the incidence among them of CAD.”• Examined the bus, tram, and trolleybus conductors, who climbed 500to 750 steps per working day on average, and the drivers, who satfor over 90% of their shift. (overall annual incidence 2.7/1000 versus1.9/1000)• The sedentary drivers had higher rates of cardiovascular diseasethan the conductors..Jeremy Morris et al (1949)
June 16, 2013 4Criticism• His study could not prove physical activity prevents CHD.• Also the workers may have been selected on the basis of their bodytype, personality or some other factor associated with high or low riskof CHD .British Civil Servant• Prospective study of middle-aged male civil servants who heldsedentary desk jobs.• Over the 3-year follow-up period they recorded 232 first clinical CADevents.• These affected individuals were then matched to two non- affectedindividuals with subsequent finding that men who recorded vigorousactivities (peak energy output of 7.5 kcal/minute) had a 33% relativerisk of developing CAD.
June 16, 2013 5• He investigated the relationship between physical activity and CVD among the postalworkers of Washington.Results• He found low CHD rates among active workers.• But their CHD changed when they switched to more sedentary lifestyle; clerks.• After 5 yrs their incidence of death from CHD was equal to that of men who has alwaysbeen clerks.• He performed further studies that showed slow movements such as gardening helpedvery little and exercise had to be more vigorous to help. His study dealt with apopulation that minimizes the possible effects of socioeconomic variation on CHDincidence, while at the same time important differences in on-the-job physical activityare included.• Criticism• His study showed that workers who are physically active have reduced risk of CHD. Hedid not measure the activity level of workers off the job.• Age factor was ignored.Harold Kahn (1963)
June 16, 2013 6Ralph Paffenbarger (1950-51)• Epidemiologist, and professor at both Stanford University School of Medicineand Harvard University School of Public Health.College Alumni Health Study• investigating the exercise habits of males of University of Pennsylvania& Harvard University alumni.• They sent questionnaire to the men.• They measured weekly total energy expenditure byusing a composite physical activity index.Ex :- flight of stairs per day (10 steps) accounted for 28 kcal/week energyexpenditure.• They divided the groups into low-energy (less than 2000 kcal/week) andhigh-energy categories (more than 2000 kcal/week).• Cohort included 36500 male alumni who entered college from 1916 to 1950.• At time of enrollment it was customary to have a routine physicalexamination, thus providing an extensive baseline record.Results• Less active alumni had an increased risk of heart attack as compared tothose who were active.• When combined with the other independent risk factors of smoking orhypertension, they found that the presence of all three conferred a relativerisk of 7.70, as opposed to 2.78 for the presence of any two factors and 1.50for any one factor.
June 16, 2013 7Other Studies….• Leon et al. (1997) studied 12,138 middle-aged men for 16 years; 29% lower CHDmortality and a 22% lower all-cause mortality for least vs. moderately active.• Rosengren et al. (1997) studied 7142 men in Sweden aged 47-55 followed for 20years ; RR=0.72 for CHD death and RR=0.70 for total mortality in most vs. leastactive.• Blair et al. (1989) followed 10,224 men and 3,120 women for 8 years; RR=1.58 formen and 1.94 for women for all-cause mortality in those in lowest vs. highestfitness quintile.• Ecklund et al. (1988) showed in 4276 men aged 30-69 followed 10 years RR forCVD mortality of 2.7 and CHD death 3.2 per 35 beats/min from submaximaltreadmill testing• Study of 3331 Japanese men showed frequency of physical activity related toHDL and number of risk factors--those who exercised 1,2, and >=3 days perweek had 1.38, 1.19, and 0.99 risk factors.• PEPI study showed in 851 post-menopausal women self-reported physicalactivity positive associated with HDL and inversely related to insulin andfibrinogen
June 16, 2013 8Later StudiesToronto Symposium (2000): Evidence for dose- response relationship• PURPOSE:To summarize and synthesize existing literature providing evidence of a dose-response relation between physical activity and CVD endpoints.• Findings supplemented by existing consensus documents and other publishedliterature. Only studies with greater than two physical activity exposurecategories were included.• Existing studies were classified by outcome used: all cardiovascular disease(CVD), coronary (ischemic) heart disease (CHD), and stroke.• Prospective observational studies and has been conducted in European men orpopulations of men of primarily European descent.• Follow-up intervals ranged from 3 to 26 yr.• Consistent inverse relation was found.• Methodological advances in physical activity assessment; additional studies onchanges in the physical activity, as it relates to the outcome.• More studies among women and ethnically diverse populations are needed toclarify these relations.•
June 16, 2013 9Do Women & Men BenefitEqually??Iowa Study• Postmenopausal women• Older women who exercised 4 times a weekhad much lower rates of all- cause mortalitythan women who were sedentary.• Vigorous activity also reduced death rates butwas not superior to moderate.Nurses’ Health Study• Middle aged and older women can reduce their risk of deathby 20-30% and benefits CVD more than cancer.
June 16, 2013 10Ralph Paffenbarger et al• 37 prospective cohort study & 1 retrospective study that dealt with all-cause mortalityand both PA & Physical fitness in women.5 Q’s1. Do highly active women postpone their death by their PA?2. Do gender- differences exist regarding PA & all –cause mortality?3. Is there a dose-response relationship between levels of activity in women andmortality?4. How much activity is required for women to benefit?5. Does age play a role?ANSWERS1. Inactive women were much more likely to have died during the study.2. Studies were almost the same as that of men.3. Evidence is not robust for a dose response relationship.4. Energy expenditure of 1,000 calories is probablyadequate to avoid premature death.5. Women below 55 benefit more.
June 16, 2013 11Conclusion• Excluding disability and potential health conditions, men and women both stand to benefit fromphysical exercise, although their motivation for partaking in physical activity is believed to holdvariance.• Marks et al., (2006) state that women pursue physical activity as a means to maintain a positivebody image while men pursue physical activity through the reward of engaging in sport andmaintaining fitness.• San Antonio Heart Study conducted by Rainwater et al., (2010) did find that a change in physicalactivity over a five-year period reduced cardiovascular risk factors to a slightly greater degree inmen as opposed to women.• However, a majority of current research suggests that men and women both physiologicallybenefit from physical exercise equally.• At least 150 minutes of exercise each week to help control weight and keep your body healthy.• Physically active people increase their longevity of about 2 yrs.• Both women & men who smoke, are overweight, have high cholesterol level can lower CVD riskby engaging in light to moderate exercise.•
June 16, 2013 12Physical Activity & CholesterolLevels• A waxy, fat-like substance, serves necessary functions within the body, including theproduction of hormones, the support of cellular membranes and the production of bileacids necessary for digesting fats.• Too much cholesterol causes formation of plaque.• Plaque restricts the flow of blood to the heart, causes heart disease and can lead to aheart attack or stroke.• Both diet and physical activity level affect cholesterol levels.• Researchers now believe there are several mechanisms involved. First, exercisestimulates enzymes that help move LDL from the blood (and blood-vessel walls) to theliver.• From there, the cholesterol is converted into bile (for digestion) or excreted. the more isthe exercise, the more LDL is expelled.• Second, exercise increases the size of the protein particles that carry cholesterolthrough the blood. (The combination of protein particles and cholesterol are called"lipoproteins;" its the LDLs that have been linked to heart disease).• Some of those particles are small and dense; some are big and fluffy. "The small,dense particles are more dangerous than the big, fluffy ones because the smaller onescan squeeze into the [linings of the heart and blood vessels] and set up shop there.• But now it appears that exercise increases the size of the protein particles that carryboth good and bad lipoproteins.
June 16, 2013 13• 2 major types of cholesterol: low-density lipoprotein, or LDL, and high-density lipoprotein,HDL.• HDL helps to remove excess cholesterol from the body, so the higher the level the lowerthe risk for heart disease.• Participating in frequent aerobic physical activity increases your HDL by 5 percent overyour cholesterol level at a sedentary lifestyle.• Some researchers conducted experiments on monkeys & found PA reduced cholesterol& artherosclerosis.• PA without dietary changes reduces Cholesterol level among humans by bringing totalcholesterol to HDL.• Review of Toronto Symposium found that walking & gardening increases HDL & reducedVLDL & LDL.• Moderate activity reduces HDL but strenuous activity does not provide extra benefit.• In a study of overweight, sedentary people who did not change their diet, the researchersfound that those who got moderate exercise (the equivalent of 12 miles of walking orjogging per week) did lower their LDL level somewhat.• But the people who did more vigorous exercise (the equivalent of 20 miles of jogging aweek) lowered it even more.• More vigorous aerobic activities, such as brisk walking, running, swimming, bicycling,roller skating, and jumping rope—done most days of the week for at least 30 minutes—are best for improving the fitness of the heart and lungs.• Moderate levels of physical activity confer significant health benefits.
June 16, 2013 14Conclusion• People can gain benefit when they move from sedentary lifestyle to active one.• Walking especially for older people protects against CVD.• Inactive lifestyle = Diabetes, High Cholesterol level, Smoking, High BP.• Physically fit men & women can reduce their CVD risk by indulging in leisure- timeactivities.• Exercise does years ago cannot provide much protection against all- cause mortality.• Moderate to intense activity can reduce risk for heart disease.Ex- Nurses’ Health Study showed that active womenreduced their risk of ischemic stroke by 34% ascompared to sedentary lifestyle women.• Meta – analysis found that high levels of occupational and leisure-timephysical activity can reduce risk of both ischemic stroke & hemorrgraphicstroke.• Lifestyle that has some physical activity can help protect against prematureCVD.
June 16, 2013 15Conclusion• Men, women 7 children of all ages benefit with physicalexercise.• To reduce Cholesterol High intensity exercise benefitsmore than moderate exercise.• “Some exercise is better than none; more exercise isbetter than some.”“Love Yourself”