The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

 
 
 

Multiple Measures of Adiposity, Cardiorespiratory Fitness, and All-Cause Mortality in Men

Posted in
Live well

Thursday, Jul 24, 2014

 

It is well-known that obesity and sedentary lifestyle are each strongly associated with all-cause mortality. Among Cooper Clinic patients, cardiorespiratory fitness (CRF) is measured via a maximal treadmill stress test, while adiposity status is measured via Body Mass Index (BMI), waist circumference, and percent body fat using the 7-site skinfold caliper method. It is not uncommon for an individual to be classified as obese using one measure of adiposity and non-obese using another measure. For example, one might be classified as non-obese when using BMI, but be classified as obese when using waist circumference. We designed a study to examine the additive effects of these measures of adiposity on all-cause mortality in men while simultaneously considering CRF.

 

A total of 36,836 men underwent a physical exam in the Cooper Clinic between 1971 and 2006. Men were identified as being either obese (positive) or non-obese (negative) for each adiposity measure by using standard cut points*, then grouped into 4 categories: group 1 was negative for each adiposity measure; group 2 was positive for any 1 measure; group 3 was positive for any 2 measures; and group 4 was positive for all 3 measures. The cohort was then followed for an average of 15.5 years; 2294 deaths occurred during this time.

After taking smoking status and age into account, group 1 had the lowest risk of death. Group 2 had a slightly higher risk when compared to group 1, while groups 3 and 4 had a 37% and 87% greater risk of death respectively as compared to group 1. In other words, the greater the number of positive adiposity measures present, the greater the risk of all-cause mortality. This is illustrated in Figure 1.

Next, we compared death rates among fit versus unfit men within the 4 groups. As is traditionally done in the Cooper Center Longitudinal Study, men were categorized as unfit if they scored in the bottom 20% compared to other men in their age group, and were categorized as fit if they scored above the bottom 20%. In each of the 4 groups, fit men had markedly lower death rates than unfit men. This is illustrated in Figure 2.

In summary, we found that using multiple measures of adiposity is preferable to using only one measure to determine risk of all-cause mortality in men. More importantly, we found that mortality risk was more accurate when CRF is also measured. In all 4 groups, risk of death was substantially lower in fit compared to unfit men. Health and fitness professionals are encouraged to make a much stronger effort to counsel their low-fit clients in the area of physical activity, regardless of the client’s adiposity status. Furthermore, we strongly recommend that a measurement or estimate of CRF be performed in order to identify men at increased risk for all-cause mortality.  Currently, CRF is the only major risk factor that is not routinely measured or estimated during a physical examination.

*The following values were used to identify the obese category for each measure of adiposity: BMI >30 kg/m2, waist circumference >40 inches, percent body fat >25%.

To learn more about assessing body composition and cardiorespiratory endurance, as well as how to set goals and write programs for clients who wish to improve in these areas, consider taking either the Personal Trainer Education or the Law Enforcement Fitness Specialist course.

 

 

Reference

Farrell, S.W., Finley, C.E., Jackson, A.W., Vega, G.L., Morrow, J.R. (2014). Association of Multiple Adiposity Exposures and Cardiorespiratory Fitness with All-Cause Mortality in Men: The Cooper Center Longitudinal Study. Mayo Clinic Proceedings.  89(6):772-780.