In the first study, which was carried out by a team of researchers from The Cooper Institute in Dallas, Texas, more than 40,000 men went through a comprehensive physical examination between Jan. 1, 1978 and Dec. 31, 2010. The exam involved a maximal treadmill exercise test to calculate the cardiorespiratory fitness level of the participant. The exam likewise measured the blood triglyceride/high-density lipoprotein ratio of each participant, which was easily measured by taking the fasting blood triglyceride level and dividing it by the blood HDL cholesterol level. A lower ratio means that insulin is functioning properly, while a higher ratio suggests resistance to insulin and shows a higher risk of prediabetes, type-2 diabetes, and cardiovascular disease in the future.
The participants were then categorized into three groups — low, moderate, and high cardiorespiratory fitness groups. For an average follow-up period of 16.6 years, 556 deaths occurred because of coronary heart disease. Results showed that moderate to high levels of fitness prevented some of the adverse effects of a high blood triglyceride/high-density lipoprotein ratio and gave protection from death due to coronary heart disease. Even lower values for the triglyceride/high-density lipoprotein ratio also gave significant protection.
The researchers observed that the lowest risk of death due to coronary disease was among high fit men in the lowest category of triglyceride/high-density lipoprotein ratio, while the highest risk was observed among low fit men in the highest category of triglyceride/high-density lipoprotein ratio. A person's cardiovascular disease risk status can be more accurately determined when the patient's level of cardiorespiratory fitness is measured together with other risk factors, such as blood pressure, bloodwork, and family history. (Related: Poor Fitness Associated with Increase in Prevalence of Cardiovascular Disease (press release).)
“While it is still extremely important to measure traditional risk factors such as resting blood pressure, blood cholesterol, triglyceride, and glucose levels, having a measure or estimate of the patient's cardiorespiratory fitness level gives us additional information regarding cardiovascular risk,” explained Stephen Farrell.
“Regardless of whether the blood TG:HDL (triglyceride/high-density lipoprotein) ratio was low or high, having at least a moderate level of fitness provided some protection from CHD (coronary heart disease) death when compared to having a low level of fitness,” he added.
In another study, which was conducted by researchers in Spain, the importance of monitoring cardiorespiratory fitness for early detection of current and future cardiovascular risk in youth was highlighted. For the study, they analyzed the data of over 2,000 youths aged between six and 18 who were part of the UP&DOWN study and 213 primary school children were examined. After a two-year follow-up period, they found that measuring cardiorespiratory fitness in children can reveal signs of increased cardiovascular disease risk in the future.
“Although CVD (cardiovascular disease) events occur most frequently during or after the fifth decade of life, there is evidence indicating that CVD precursors have their origin in childhood and adolescence. Moreover, adverse CVD risk factors during childhood have been found to track into adulthood,” explained José Castro-Piñero from the University of Cádiz and lead researcher of the study.
They believe that early discovery and diagnosis of cardiovascular disease risk factors in children and adolescents will help in the development of effective prevention programs, counseling, school-based strategies, and public health policies.