How to overcome poor cardio fitness.
If you've had trouble improving your low VO2 max and you don’t feel naturally inclined toward endurance exercise, there may be several factors affecting your struggle with cardio conditioning. Body mass index, body fat distribution, aging, nutrition, sleep quality, stress, and genetics can all affect your ability to exercise and improve from training. Low VO2 max is proven to affect our survival rate and risk of death, which makes these seven factors worth examining further.
Low VO2 max, body weight and body fat distribution
42% of US adults are currently obese (BMI > 30), and studies show that VO2 max trends higher for those with a lower body mass index and a smaller waist circumference (1-2). Hurdles to becoming fitter include a higher likelihood of arthritis and chronic pain at BMI > 30 compared to lighter-weight peers (3-4).
Despite the challenges, an increasing number of obese people are finding ways to maintain good cardio fitness. A 2018 review of studies found that people who are obese and fit have a lower mortality risk than normal-weight peers who are out-of-shape (5).
According to numerous studies, VO2 max is more important than BMI for preventing all-cause and cardiovascular mortality. (1, 5-6) Higher fitness in people with a BMI > 30 is associated with metabolic health indicators, such as normal blood pressure, cholesterol, and blood sugar (7).
Maintaining a strong VO2 max at a high body weight is an impressive achievement, shown to be highly beneficial for your long-term health. But it may be easier said than done, particularly for those with a high waist circumference (6). People with a BMI below 30 are significantly more likely to maintain good cardio fitness for the long term than those above 30. Look up your BMI and learn more about the health effects of body mass index in this article.
Low VO2 max and aging
On average, VO2 max tends to decline slowly in young adulthood at about 5% per decade, increasing to 10% per decade in middle age and about 15% per decade through the retirement years (1, 8, 9). Decreasing space for blood flow in the heart and blood vessels, smaller air sacs in the lungs, and less elasticity in the heart valves and lung tissue may explain this change in the body's performance over time (10).
This age-related decline seems to occur in people of all ability levels, from non-exercisers to fit and athletic people. The advantage for fit people who remain active is that their conditioning compares favorably with adults 20 or 30 years younger (1). Learn more about the effect of exercise on aging in this article. Studies show that with concentrated effort you can improve your low VO2 max, even later in life (11). There are even senior athletes who increased their aerobic capacity steadily over years of training.
Low VO2 max and nutrition
The typical Western diet is calorie-dense and nutrient-poor. 58% of calories consumed in the US are from ultra-processed foods, such as cookies, cakes, chips, soda, and processed meat (12). By contrast, the Mediterranean Diet, which includes a high intake of fruits and vegetables, legumes, olive oil, grains, potatoes, and smaller portions of eggs, cheese, fish, and poultry, has long been associated with longevity and improved cardiovascular health. A review of studies found that high adherence to the Mediterranean Diet is also associated with improved cardiovascular and overall physical fitness (13).
Low VO2 Max and Stress
The American Psychological Association reported that 34% of adults are overwhelmed by stress (Stress in America 2022). Symptoms include headache, fatigue, anxiety, depression, and difficulty sleeping. Over 70% of adults experience negative impacts either on their eating habits, interests in hobbies or activities, or physical health. Though stress can interfere with our exercise training, even a single exercise session can reduce symptoms. Developing a higher level of cardio fitness can even lower your reactivity to acute stressors (14, 15).
Chronic work or relational stressors can lead to increased blood pressure and higher risks of cardiovascular disease, such as arrhythmia, MI, and heart failure. Improving a low VO2 max through cardiovascular training is an effective way to control the risk of these conditions, though the untrained should start slowly for the first 6-8 weeks to lower their risk of an acute cardiac event (14, 15).
Low VO2 max and sleep quality
About 1/3 of US adults get less than 7 hours of sleep per night. (16) A review of studies found that total or partial sleep deprivation, going to bed too late, or waking up early (without getting enough sleep) had a moderate detrimental impact on endurance performance (17). In addition, lack of sleep has been shown to limit recovery after exercise and increase the risk of injury from exercise, all of which can worsen your results from training. Fortunately, given a sufficient time window for rest each night, consistent cardiovascular exercise can improve sleep quality just as it reduces symptoms of stress (18).
Low VO2 max and genetics
As we might expect to find with any human ability, studies have shown that low VO2 max and the trainability of cardio fitness may vary due to inherited ability and family environments. The Heritage Family Study observed significant differences in VO2 max in a diverse population of young and middle-aged males, all of whom had sedentary activity levels (19, 20). They found up to a 50% difference in VO2 max when comparing the majority (2/3) of participants. Heritage estimated that 30% of this difference in untrained VO2 max comes from genetics, in agreement with other studies (21).
Heritage also found differences in response to training among their participants. While most of the men benefited significantly from endurance training, among the middle 2/3 there was a 70% difference in their improvement of VO2 max after exercise training. Heritage estimated that nearly 1/2 of the difference was due to genetics and family environment (20).
While some may have a natural advantage in VO2 max and trainability, even genetics can be affected by training, according to a 2008 study. Telomeres are structures that protect the DNA code in cells, and healthy telomeres help prevent the aging process. The study found that regular leisure-time exercise helped maintain the proper length of telomeres in white blood cells (22).
Overcoming limiting factors to improve your low VO2 max
The factors that can limit your success in VO2 max training may be complex and multifaceted, but the solutions are often more straightforward. Establishing a doable training program you’ll look forward to practicing is central to your success at any age or condition. Get ideas for incorporating more activity into your weekly routine in this article. If you haven’t tested yourself yet, visit this article to pick your fitness test and find out where you stand! (You'll also learn the most effective methods for improving your cardio fitness.)
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21) SARZYNSKI, MARK A.; RICE, TREVA K et al., The HERITAGE Family Study: A Review of the Effects of Exercise Training on Cardiometabolic Health, with Insights into Molecular Transducers. Medicine & Science in Sports & Exercise 54(5S):p S1-S43, May 2022. | DOI: 10.1249/MSS.0000000000002859
22) The Association Between Physical Activity in Leisure Time and Leukocyte Telomere Length 2008, Lynn F. Cherkas, PhD; Janice L. Hunkin, BSc; Bernet S. Kato, PhD; J. Brent Richards, MD;