The Cooper Institute
 

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

 
 
 

Does Fitness Level in Midlife Translate to Developing Chronic Conditions in Later Life? The Cooper Center Longitudinal Study

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Tuesday, Jul 13, 2021

We have known for three decades that cardiorespiratory fitness (CRF) is strongly and inversely related to the risk of premature death from a variety of causes.


With all other factors being equal, individuals with moderate or high levels of CRF are substantially less likely to die early when compared to individuals with low levels of CRF. Because the median age of U.S. residents is increasing, many studies are now focusing on healthy aging, i.e. preventing premature chronic health conditions.


One aspect of healthy aging is the concept of compressed morbidity, which can be explained as follows: As we age, the goal should be to remain as healthy and functional until as late in life as possible. When a chronic condition does develop very late in life, the period of time from diagnosis to death is short, i.e. compressed. This is illustrated in Figure 1 below.


Compressed morbidity places a much lower burden on the individual and their family members, as well as on our health care system. Accordingly, researchers at The Cooper Institute examined the association between midlife CRF and the risk of developing 8 common chronic health conditions later in life. These conditions included congestive heart failure, coronary heart disease, stroke, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, Alzheimer’s disease, and colon or lung cancer.    

A total of 18,670 healthy adults with an average age of 49 years underwent a comprehensive baseline physical examination at the Cooper Clinic between 1970 and 2009.
 

Men and women comprised 79% and 21% of the sample, respectively. The examination included a maximal treadmill exercise test, which is the gold standard measure of CRF. Men and women were divided separately into 5 groups (quintiles) of CRF according to their age group. All patients became eligible for Medicare (i.e. age 65) between 1999 and 2009. Medicare claims data were then obtained for the sample, and rates of chronic conditions per 10 person-years* of follow-up were determined. The average length of follow-up from the time of the baseline examination was 26 years. In Figure 2 below, the rates of chronic conditions that developed during the follow-up period are shown across quintiles of CRF for men and women.


The Figure shows a strong inverse trend in rates of chronic conditions across quintiles of midlife CRF. Men in the lowest CRF quintile had a rate of 2.82 chronic conditions per 10 person-years of follow-up, while the rates were 2.24, 2.01, 1.78, and 1.56 for the remaining 4 quintiles, respectively. For women, the rates of chronic conditions were 2.01, 1.66, 1.43, 1.23, and 1.14 across quintiles of midlife CRF, respectively. These trends were statistically significant for both genders. Thus, higher levels of midlife CRF were associated with a decrease in the number of chronic conditions later in life. It’s important to note that during the analyses, the researchers took many other factors such as smoking, blood cholesterol levels, and body mass index (BMI) into consideration. Development of chronic conditions was also associated with higher midlife values for resting blood pressure, body mass index (BMI), blood cholesterol and blood-glucose levels, as well as higher smoking prevalence.

During the follow-up period, there were 2406 deaths. Another significant finding in this study was that the length of time between the onset of chronic conditions, and the time of death was decreased at higher levels of baseline CRF. This reflects the concept of compressed morbidity that we mentioned previously. So, not only was CRF associated with a decreased number of chronic conditions later in life, but also with a delayed onset of these conditions relative to time of death.

The takeaway message here is that all adults should strive for at least a moderate level of CRF at midlife so that the risk of chronic conditions later in life is reduced, and so that the onset of these conditions is delayed. Accumulating at least 150 minutes per week of moderate intensity aerobic exercise on a regular basis should result in achieving a moderate level of CRF for most individuals. Avoiding tobacco and obesity, keeping blood pressure, blood cholesterol, and blood-glucose levels in check, as well as consuming more plant-based foods and limiting alcohol intake can often result in compressed morbidity later in life.

As Dr. Cooper is fond of saying “the goal should be to live a long, healthy and independent life, then die suddenly as late in life as possible.”


*Rates of disease are expressed in this article per 10 person-years of follow up. For example, if 1 person is followed for 1 year, then there is 1 x 1 = 1 person-year of follow-up. If 1 person is followed for 10 years, then there are 1 x 10 = 10 person-years of follow-up.

Reference
Willis, B. L., Gao, A., Leonard, D., DeFina, L. F., Berry, J. D.  Midlife fitness and the development of chronic conditions in later life. (2012). Arch Intern Med, 172(17), 1333-1340.  doi: 10.1001/archinternmed.2012.3400