The Cooper Institute
 

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

 
 
 

Cardiorespiratory Fitness, White Blood Cell Count, and Mortality in Men and Women: The Cooper Center Longitudinal Study

Posted in
Cardio

Thursday, Nov 11, 2021

 

 As you may be aware, cardiorespiratory fitness (CRF) as well as inflammation are two hot topics in the health and fitness research field. CRF is best thought of as the ability of the body to use oxygen at the cell level, and can be objectively measured via maximal treadmill exercise testing in a clinical setting. White blood cell count (WBC) is a common and inexpensive test that measures inflammation levels within the body. The higher the WBC, the greater the amount of inflammation present. Both CRF and WBC are important predictors of mortality. Our research team examined the relationship between CRF, WBC, and all-cause, cardiovascular disease, and cancer mortality in men and women.

Our goal was to look at all possible combinations of CRF and WBC at baseline, then examine subsequent mortality risk. The results were recently published in the Journal of Sport and Health Science.

How the Study was Done 

We studied 52,056 healthy adults (29% women) with an average age of 45 years, who completed a comprehensive health examination at the Cooper Clinic between 1978 and 2016. The exam included a maximal treadmill exercise test to measure CRF as well as blood analysis for white blood cell count (WBC). The participants were then divided into High, Moderate, and Low CRF based on their age and sex. Participants were also divided into four categories of WBC ranging from Low to High. We examined mortality risk for High, Moderate, and Low CRF within each of the four categories of WBC, and examined men and women separately. Several factors that might have affected our observations were taken into account.

These included age, body mass index, resting blood pressure, blood cholesterol and glucose levels, and smoking.

What Were the Results?

       There were a total of 4088 deaths during an average of 18 years of follow-up. About 63% of deaths were from cardiovascular disease and cancer, which is consistent with U.S. population data as a whole during that same time period. For men, higher levels of CRF were associated with reduced all-cause, cardiovascular disease, and cancer mortality risk within each category of WBC. Therefore, regardless of the level of inflammation present, higher levels of CRF helped protect against mortality in men. For women, the results were not as consistent. CRF was protective against all-cause, cardiovascular disease, and cancer mortality only in those within the highest category of WBC. For both men and women, the highest risk of all-cause mortality was seen among those with the lowest levels of CRF and the highest levels of WBC. At this point, we can only speculate as to why the results were less consistent in women. It may have been due to different patterns of body fat distribution in women, or hormonal differences between men and women.  

Action Points 

        Since both CRF and WBC are important predictors of mortality, it is important to have these health markers measured. While WBC is measured in a clinical setting, CRF can be either measured in a clinical setting via a maximal treadmill exercise test, or estimated outside of a clinical setting utilizing methods such as the Rockport Walking Test or the Cooper 12-Minute Run Test.

        Individuals who are found to have low CRF should strive to meet current public health guidelines for physical activity, that is, accumulate at least 150 minutes each week of moderate intensity aerobic physical activity and perform resistance training at least two days each week. For individuals who are very sedentary, it may take several weeks to gradually build up to recommended physical activity levels. Individuals found to have elevated WBC should consult with their health care provider regarding strategies to decrease inflammation. These lifestyle strategies typically include avoiding tobacco in all forms, performing regular physical activity, losing weight if overweight, and consuming a heart healthy diet such as the DASH Eating Plan or the Mediterranean Diet. From a pharmacological perspective, in addition to lowering blood LDL-cholesterol and triglyceride levels, statin drugs have also been shown to reduce inflammation. 

Reference

Farrell SW, Leonard D, DeFina LF, Barlow CE, Shuval K, Pavlovic A, Haskell, WL.  

Cardiorespiratory fitness, white blood cell count, and mortality in men and women. Journal of Sport and Health Science. Published online ahead of print. November 3, 2021