Cardiorespiratory Fitness Cardiorespiratory Fitness and Adiposity as Mortality and Adiposity as Mortality Predictors in Older AdultsPredictors in Older Adults

JAMA December 5, 2007JAMA December 5, 2007

BackgroundBackground

32% of Americans are obese32% of Americans are obese Obesity is associated with a number of Obesity is associated with a number of

health problemshealth problems 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 There is little data regarding

associations among obesity, physical associations among obesity, physical activity and mortalityactivity 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 cardiorespiratory fitness, adiposity and mortality on older adultson older adults

Cohort Study: prospective study of 2,603 adults Cohort Study: prospective study of 2,603 adults > 60 yrs> 60 yrs Had to achieve 85% HR on treadmill test to be Had to achieve 85% HR on treadmill test to be

includedincluded Patients grouped into quintiles based on duration of Patients grouped into quintiles based on duration of

testtest Also grouped by BMI, waist circumference, body fat % Also grouped by BMI, waist circumference, body fat %

and fat free massand fat free mass Patients completed a comprehensive health Patients completed a comprehensive health

evaluation, physical exam, blood lipids and evaluation, physical exam, blood lipids and glucose and EKGglucose and EKG

Methods Cont.Methods Cont.

Used METS (metabolic equivalent Used METS (metabolic equivalent tasks) based on treadmill speed and tasks) based on treadmill speed and grade to standardize interpretationgrade to standardize interpretation

Outcome was all-cause mortalityOutcome was all-cause mortality Multivariate analysis performed Multivariate analysis performed

using age, sex, exam year, smoking, using age, sex, exam year, smoking, abnormal exercise EKG and chronic abnormal exercise EKG and chronic medical conditionsmedical conditions

ResultsResults

Table I - HighlightsTable I - Highlights

• 20% women20% women

• BMI and waist BMI and waist circumference was the circumference was the same for both groupssame for both groups

• Treadmill time was 2 Treadmill time was 2 minutes less in minutes less in decedentsdecedents

• HDL was 4 pts HDL was 4 pts higher in survivors, as higher in survivors, as was incidence of was incidence of hypercholesterolemiahypercholesterolemia

• Smoking was 5% Smoking was 5% more prevalent in more prevalent in decedentsdecedents

Table II - Table II - HighlightsHighlights

• Opposing trend in Opposing trend in fitness quintile for fitness quintile for lowest and highest lowest and highest BMI groupsBMI groups

• HDL directly HDL directly correlated w/ fitness correlated w/ fitness quintilequintile

• Except in lowest Except in lowest quintile, smoking quintile, smoking inversely correlated inversely correlated w/ fitnessw/ fitness

• Except in highest Except in highest quintile, quintile, hypertension and hypertension and cholesterol directly cholesterol directly correlated w/ fitnesscorrelated w/ fitness

• One BMI > 35 One BMI > 35 actually made it 18 actually made it 18 minutesminutes

Table IV - Table IV - HighlightsHighlights

• J-shaped J-shaped relationship relationship between BMI between BMI and mortality and mortality

• EKG changes, EKG changes, chronic medical chronic medical conditions and conditions and waist waist circumference circumference correlate w/ correlate w/ mortalitymortality

• Percent body Percent body fat and fat free fat and fat free mass did notmass did not

• Hazard ratios for fitness and adiposity -> results Hazard ratios for fitness and adiposity -> results show better fitness = better mortalityshow better fitness = better mortality• Initially adjusted for 1) age, sex, EKG changes, Initially adjusted for 1) age, sex, EKG changes, smoking, exam year and medical conditions smoking, exam year and medical conditions • Additional adjustments for 2) BMI, 3) waist Additional adjustments for 2) BMI, 3) waist circumference, 4) percent body fat and 5) fat-free circumference, 4) percent body fat and 5) fat-free mass 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, Homogeneous study group (white,

educated, middle and upper class)educated, middle 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 Does not really address association

between a spot fitness check and daily between a spot fitness check and daily cardiovascular exercise cardiovascular exercise

Small number of women and few deaths Small number of women and few deaths within this groupwithin this group

ConclusionsConclusions Fitness is a strong predictor of overall Fitness is a strong predictor of overall

mortality independent of body compositionmortality independent of body composition Assuming an otherwise healthy individual, Assuming an otherwise healthy individual,

there is no association betw abdominal obesity there is no association betw abdominal obesity and mortality when adjusted for fitnessand mortality when adjusted for fitness

Fit individuals who are obese had lower Fit individuals who are obese had lower mortality than unfit normal-weight or lean mortality than unfit normal-weight or lean individualsindividuals

Fat distribution and frame size may be more Fat distribution and frame size may be more important than adiposityimportant than 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 mortality, both before and after adjusting for fitnessfitness

FINFIN