Aerobic Fitness & Heart Health for Adults
Know Your Numbers
Last week I posted on ‘Aerobic Fitness in Youth’ to raise some attention to its importance in relation to cardiovascular health during American Heart Month.
Although much of my work is targeted at youth, the general principles about physical qualities like aerobic fitness and training methods in youth apply to those in adults. Testing maximal aerobic fitness using lab-based Vo2max or field-based estimates like the 1-mile run are very similar (if not the same) in children and adults - we just need to take into account growth, maturation and development in youth. We probably explain the test a bit differently, maybe make some modifications to equipment or protocol and handle the data a bit differently (i.e., different prediction equations, etc.).
As I was writing that piece, my mind kept going to the adults. Not just because they would be the one’s reading it and implementing it into their practice of pediatric exercise science, sports medicine, physical education, strength & conditioning or coaching; but also because the adults really need to listen and act on aerobic fitness and cardiovascular health as well.
Just look around ……. we probably do not need to test the adult population to confirm that many are unfit.
By the Numbers
Heart disease is the leading cause of death in the U.S. and many other countries. In 2020, nearly 700,000 people in the United States died from heart disease —that’s 1 in every 5 deaths (20.6% of all deaths). Put in another context - one person dies every 34 seconds from cardiovascular disease (CVD). So by the time you finish reading this blog, 6 people will die from CVD.
CDC Local Trends in Heart Disease and Stroke Mortality Dashboard
CDC Interactive Atlas of Heart Disease and Stroke
We could further break down these CVD stats (see links above) but what I really want to focus on the risk factors and knowing your numbers.
The CDC (Centers for Disease Control and Prevention) lists the following risk factors for heart disease:
High blood pressure (>120/80)
High cholesterol (total cholesterol >200 mg/dl; “bad” LDL cholesterol >130 mg/d; “good” HDL cholesterol <40 mg/dl); triglycerides <150 mg/dl)
Smoking🚬
Diabetes (fasting glucose >100 mg/dl)
Overweight (BMI 25-29.9 kg/m2) and obesity (BMI >30 kg/m2)
Unhealthy diet
Physical inactivity (150 minutes per week of moderate-intensity physical activity + 2 days of muscle strengthening)
Excessive alcohol use🍻 (8+ drinks per week for a woman; 15+ drinks per week for a man)
They further state that high blood pressure and cholesterol and smoking are the key risk factors for heart disease. These risk factors, along with age and sex, are part of the Framingham Risk Score which estimates 10-year risk of heart attack. If you know your numbers, determine your Risk Score here. If you don’t know your numbers, please consider scheduling a check-up with your physician or finding a heart health screening.
What about aerobic fitness as a risk factor for heart disease?!
Yes, physical inactivity is listed as a risk factor - but physical activity and (aerobic) fitness are not the same thing. Yes, they are related; however, it is not a strong correlation - as physical activity is a behavior and the intensity of activity can also vary and may not impact fitness; in turn, aerobic fitness is a physiological trait and can be impacted by genetics.
So, what about aerobic fitness? Let’s start here. It’s 1968 and Dr. Kenneth Cooper coins the term “Aerobics” in the 1968 best-selling book of the same name alongside the 12-minute walk/run test of aerobic fitness. Dr. Cooper subsequently founded the Cooper Clinic devoted to preventive medicine. Part of the comprehensive evaluation of the patient is a treadmill exercise test and of course full CVD risk factor profile workup. These patients become enrolled in the Cooper Center Longitudinal Study, which has produced 700+ research papers that include some of the most impactful research on physical fitness and health.
One of those papers published in the Journal of the American Medical Association in 1989 is regarded as a landmark report clearly establishing that aerobic fitness is a powerful predictor of outcomes across the spectrum of health and disease. Over the next few decades, several other research reports also found similar robust findings. In fact, aerobic fitness appears to be a more powerful predictor of CVD risk than the other traditional risk factors!
Aerobic fitness as a risk factor clinical vital sign!
In 2016, the evidence of research linking aerobic fitness with heart disease and other chronic diseases was recognized by the American Heart Association in a scientific statement which suggested that aerobic fitness be considered a clinical vital sign.
How to determine the vital sign of aerobic fitness?
Pre-participation screening. First, make sure you are ready to roll. Although most people can exercise without visiting a physician, some should seek medical clearance first. Since a test of aerobic fitness will require a vigorous effort, please make sure you are in the clear. Use this screening algorithm from the American College of Sports Medicine.
Testing. As briefly describe in the blog on youth aerobic fitness, testing can occur in the lab or on the track.
Maximal exercise testing in the lab requires sophisticated and expensive equipment and a well-trained exercise physiologist. Most labs (either clinical or university) will charge a fee of $75-250.
More than likely, you will opt for the free and relatively simple approach of a field measures like the 1 mile or 12-min run. Just grab your sneakers and a stopwatch.
1-Mile Endurance Run / Walk Test
Evaluation of test results. You’ll need to do some maths to calculate the estimed Vo2max. Once you have this value, use the reference values chart below to determine and evaluate your level of aerobic fitness.
What’s a good Vo2max?
Ok, if it’s a clinical vital sign, then we better measure it just like resting heart rate and blood pressure!
In the previous post focusing on youth, I highlighted our studies which set reference standards for youth aerobic fitness. Again, estimated Vo2max values of 40-44 ml/kg/min for adolescent males and 38-40 ml/kg/min for adolescent females conferred being in the “Healthy Fitness Zone”.
As we enter our twenties (young adulthood), these values stay relatively stable - unless of course you turn towards a completely sedentary lifestyle. Again, Vo2max is a physiological trait. It’s also a “plastic” or malleable trait, meaning that it (the oxygen transport system-heart/lung/vascular system/oxidative potential of muscle) will change up or down depending on the need or demand for oxygen and fitness. Put another way - use it or lose it!
I mentioned that our study of youth was part of FITNESSGRAM, the national youth fitness test battery. And since FITNESSGRAM is based out of the Cooper Clinic, it should be no surprise that adult reference values can be found here as well. Indeed, the reference values published by the Cooper Clinic are among the most commonly taught and used reference values for V̇O2peak.
Updated Reference Standards for Cardiorespiratory Fitness Measured with Cardiopulmonary Exercise Testing
The Cooper Clinic reference values have put in a lot of miles (no pun intended) over the years. However, they also have some limitations. One being that most of the participants were middle-upper class white men. And a second limitation being that Vo2max was estimated and not directly measured. Ideally, reference values would be directly measured in a representative of the population.
In response to an American Heart Association Scientific Statement on aerobic fitness being a clinical vital sign, a group of researchers and clinicians from 34 labs set up a registry or database called FRIEND (Fitness Registry and the Importance of Exercise National Database) to be used to develop reference standards. The results showing percentiles by age group for men and women are shown below. (Note: data for cycle testing is also available.)
How to maintain or improve aerobic fitness? The short and simple version
Move. Short bouts, medium bouts. Long bouts. Low / moderate / high intensity. Run/bike/walk/swim/hoops/push the lawnmower. Just move.
More on improving aerobic fitness in subsequent blogs. But for now, just move - and embrace vitality - the state of being strong and active; energy.