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Cardiorespiratory Fitness and Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Adiposity as Mortality Predictors in
Older AdultsOlder Adults
JAMA December 5, 2007
BackgroundBackground
32% of Americans are obese32% of Americans are obese Obesity is associated with a number of health Obesity is associated with a number of health
problemsproblems Vast majority of people do not exerciseVast majority of people do not exercise These trends worsen with agingThese trends worsen with aging There is little data regarding associations among There is little data regarding associations among
obesity, physical activity and mortalityobesity, physical activity and mortality What is more important, fat or fitness?What is more important, fat or fitness?
MethodsMethods
Objective: determine the association among Objective: determine the association among cardiorespiratory fitness, adiposity and mortality on cardiorespiratory fitness, adiposity and mortality on older adultsolder adults
Cohort Study: prospective study of 2,603 adults > 60 Cohort Study: prospective study of 2,603 adults > 60 yrsyrs Had to achieve 85% HR on treadmill test to be includedHad to achieve 85% HR on treadmill test to be included Patients grouped into quintiles based on duration of testPatients grouped into quintiles based on duration of test Also grouped by BMI, waist circumference, body fat % and Also grouped by BMI, waist circumference, body fat % and
fat free massfat free mass Patients completed a comprehensive health evaluation, Patients completed a comprehensive health evaluation,
physical exam, blood lipids and glucose and EKGphysical exam, blood lipids and glucose and EKG
Methods Cont.Methods Cont.
Used METS (metabolic equivalent tasks) based Used METS (metabolic equivalent tasks) based on treadmill speed and grade to standardize on treadmill speed and grade to standardize interpretationinterpretation
Outcome was all-cause mortalityOutcome was all-cause mortality Multivariate analysis performed using age, sex, Multivariate analysis performed using age, sex,
exam year, smoking, abnormal exercise EKG exam year, smoking, abnormal exercise EKG and chronic medical conditionsand chronic medical conditions
ResultsResults
Table I - HighlightsTable I - Highlights
• 20% women20% women
• BMI and waist BMI and waist circumference was the same circumference was the same for both groupsfor both groups
• Treadmill time was 2 Treadmill time was 2 minutes less in decedentsminutes less in decedents
• HDL was 4 pts higher in HDL was 4 pts higher in survivors, as was incidence of survivors, as was incidence of hypercholesterolemiahypercholesterolemia
• Smoking was 5% more Smoking was 5% more prevalent in decedentsprevalent in decedents
Table II - HighlightsTable II - Highlights
• Opposing trend in fitness Opposing trend in fitness quintile for lowest and quintile for lowest and highest BMI groupshighest BMI groups
• HDL directly correlated HDL directly correlated w/ fitness quintilew/ fitness quintile
• Except in lowest quintile, Except in lowest quintile, smoking inversely smoking inversely correlated w/ fitnesscorrelated w/ fitness
• Except in highest Except in highest quintile, hypertension and quintile, hypertension and cholesterol directly cholesterol directly correlated w/ fitnesscorrelated w/ fitness
• One BMI > 35 actually One BMI > 35 actually made it 18 minutesmade it 18 minutes
Table IV - HighlightsTable IV - Highlights
• J-shaped relationship J-shaped relationship between BMI and between BMI and mortality mortality
• EKG changes, EKG changes, chronic medical chronic medical conditions and waist conditions and waist circumference circumference correlate w/ mortalitycorrelate w/ mortality
• Percent body fat and Percent body fat and fat free mass did notfat free mass did not
• Hazard ratios for fitness and adiposity -> results show better fitness = Hazard ratios for fitness and adiposity -> results show better fitness = better mortalitybetter mortality• Initially adjusted for 1) age, sex, EKG changes, smoking, exam year Initially adjusted for 1) age, sex, EKG changes, smoking, exam year and medical conditions and medical conditions
• Additional adjustments for 2) BMI, 3) waist circumference, 4) percent Additional adjustments for 2) BMI, 3) waist circumference, 4) percent body fat and 5) fat-free mass body fat and 5) fat-free mass did notdid not change the results change the results
Table VTable V
Study LimitationsStudy Limitations
Cohort -> possibility of confoundersCohort -> possibility of confounders Homogeneous study group (white, educated, middle Homogeneous study group (white, educated, middle
and upper class)and upper class) No info about diet or medication useNo info about diet or medication use Fitness tested only once at outset of studyFitness tested only once at outset of study Does not really address association between a spot Does not really address association between a spot
fitness check and daily cardiovascular exercise fitness check and daily cardiovascular exercise Small number of women and few deaths within this Small number of women and few deaths within this
groupgroup
ConclusionsConclusions
Fitness is a strong predictor of overall mortality Fitness is a strong predictor of overall mortality independent of body compositionindependent of body composition
Assuming an otherwise healthy individual, there is no Assuming an otherwise healthy individual, there is no association betw abdominal obesity and mortality when association betw abdominal obesity and mortality when adjusted for fitnessadjusted for fitness
Fit individuals who are obese had lower mortality than Fit individuals who are obese had lower mortality than unfit normal-weight or lean individualsunfit normal-weight or lean individuals
Fat distribution and frame size may be more important Fat distribution and frame size may be more important than adipositythan adiposity
There is a J-shaped relationship betw BMI and There is a J-shaped relationship betw BMI and mortality, both before and after adjusting for fitnessmortality, both before and after adjusting for fitness
FINFIN
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