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Table of contents
In this newsletter, I explain why VO2 max is such an important health metric and how you can test, interpret, and improve your VO2 max and overall fitness. These topics are covered in more detail in the podcast episodes I did titled “Building a Strong Heart” and “Improve VO2 Max & Endurance.”
VO2 Max & All-Cause Mortality
Cardiorespiratory fitness measures how well the cardiopulmonary system brings in and transports oxygen to your muscles, and how well those muscles extract that oxygen and use it for energy production. It’s measured using a VO2 max test. Your VO2 max is an important—if not the most important—marker of longevity. Higher VO2 max scores are associated with overall health improvements and reduced all-cause mortality (death from any cause).
In 1989, a landmark study led by Dr. Steven Blair found that “age-adjusted, all-cause mortality rates declined across physical fitness” levels. Blair’s study found that men and women at the lowest fitness levels had significantly higher mortality rates, but they also highlighted that even modest improvements in fitness drastically reduce risk.
Subsequent studies demonstrated that VO2 max is more predictive of longevity than traditional risk factors like smoking, diabetes, or coronary artery disease. Another large study (>750,000 participants) took into account race, sex, and other comorbidities (such as diabetes) and found similar results. Across all of these studies, the benefits of higher VO2 max don’t have an upper limit, meaning that continuing to increase your cardiorespiratory fitness will continuously benefit your health and longevity.
Testing VO2 Max
Lab testing is the gold standard for assessing your VO2 max. These tests typically cost between $75-250 and are offered by various providers. (Some high-end gyms, including podcast sponsor CONTINUUM in New York City, offer VO2 max tests as part of their membership programs. CONTINUUM also does body composition testing, blood panels, sleep testing, and more as part of its membership onboarding.) Wearables (e.g., watches, rings) can provide estimated VO2 max scores, which can help gauge your current fitness level, especially if you are new to physical training. However, current wearables lack sufficient precision and accuracy, making them less helpful for highly-trained individuals.
There are alternative methods (submaximal exercise tests) to estimate your VO2 max, including:
- The 3-Minute Step Test: take your starting heart rate, then step up and down on a small box continuously for 3 minutes. Then, measure your heart rate and enter it into this calculator to estimate your VO2 max.
- The 12-Minute Run Test (Cooper’s Test): run as far as you can in 12 minutes and note the distance. Then, use this calculator for an estimate of your VO2 max.
Interpreting VO2 Max Scores
VO2 max (aka your cardiovascular fitness) is the maximum amount of oxygen (O2) the body can utilize during exercise. It’s calculated using Fick’s Equation: VO2 max = CO × a‑vO2 difference
- CO(CardiacOutput) = Stroke Volume (SV) × Heart Rate (HR)
- Cardiac output is the volume of blood pumped per heartbeat × the number of heart beats per minute
- a-vO2 difference is the difference in oxygen concentration between the arterial and venous blood – this indicates how effectively your tissue extract oxygen
Your relative VO2 max score represents the volume of oxygen (measured in mL) you can use per kg of body weight per minute. It is conceptualized as a score from 0 to 100 mL/kg/min. (As a note, VO2 max can also be measured in absolute terms, which does not factor in body weight. This is simply mL/min.)
VO2 max scores will vary by age, sex, and fitness level. A moderately trained individual in their 20-30s will average VO2 max scores of 35-45 mL/kg/min. Scores below 18 for males and 15 for females indicate very low levels of general fitness, and these individuals likely find many daily tasks challenging to complete independently. Compare your VO2 max score to these charts sorted by age and sex.
I like to say, “There’s no excuse to be under 50 unless you are over 50,” so that is a good VO2 max score to aim for. VO2 max is highly responsive to training, making it a great fitness marker to indicate the effectiveness of your training programs and gauge changes in overall fitness.
It’s worth noting that your VO2 max is generally considered to be 50% genetically determined and 50% determined by your lifestyle and training. This is great news because it means that all of us have a lot of control over our VO2 max.
Improve VO2 Max
Fick’s equation reveals two key factors that can be improved to increase VO2 max:
- a-vO2 difference – how much oxygen is extracted and used. This can be enhanced with mitochondrial health (size, number, efficiency) or increased capillarization of tissues.
- stroke volume – i.e., the heart’s strength. The strength of the left ventricle increases with exercise to increase the volume of blood exiting the heart in each heartbeat.
Exercise is a powerful stimulus to improve both of these factors.
Exercise Intensity
When designing a training program, it’s essential to vary the exercise stimuli by alternating your training intensity. Training intensities are sometimes referred to by their heart rate (HR) zones, gears, or “colors.” While there are many ways to improve VO2 max, what follows is a very effective approach. Aim for:
- Low intensity for 70% of training (~60-80% of HR peak). You can hold a conversation while exercising at this intensity and use nasal breathing.
- Low-intensity training improves metabolic efficiency and sustained oxygen utilization. It also minimizes injury risk and reduces recovery time.
- Moderate intensity for 25% of training (80-90% of HR peak).
- High intensity for 5% of training (>90% HR peak). When training at high intensities, you can’t hold a conversation and must use your mouth to breathe.
Mode of Exercise
While the type of exercise does matter, it’s not the primary factor. The extent of VO2 max improvements depends on the extent of muscle engagement; using more muscles leads to higher oxygen utilization and greater VO2 max improvements.
Use whatever exercise mode you prefer, such as cycling, running, swimming, rowing, pulling a sled, or an assault bike. Pick something that requires high effort but which you are technically proficient at and can maintain good form for the duration of the exercise.
Beginners should be cautious with high-impact exercises (jumping, eccentric movements) to avoid injury and excessive muscle soreness. You can also vary exercise modalities throughout the week; just ensure you adhere to the intensity guidelines.
Programs & Expected Results
Following a training program can help ensure your weekly exercise regimen is designed with the above principles in mind. A good program for low- to moderately-trained individuals is Joel Jamison’s Metamorphosis Program. This 8-week program is designed specifically to improve VO2 max. Each day incorporates a warm-up, conditioning, and strength training and varies in intensity across the week.
Another excellent option is a marathon training program called Faster in 50, designed by Dan Garner. This program includes daily warm-ups, resistance, and endurance training blocks. Learn about and access the complete programs here.
Structured training across various intensities and modalities can result in up to 30-50% increases in VO2 max for untrained individuals over 6-12 months. Highly trained individuals will also be able to see improvements and can typically expect an increase of 10-20% within a year.
Remember: in the words of Bill Bowerman, “If you have a body, you are an athlete.”
Best,
Andy