Cardio Fitness and Longevity: What VO2 Max Research Really Shows
Longevity · Exercise · Prevention
By Dr. Cody Belkoff, DO · Prime Body Solutions · Liberty Lake, WA
When you come in for a checkup, we measure your blood pressure, your weight and your labs. One of the strongest predictors of how long you'll live usually doesn't get measured at all: how fit your heart and lungs are.
That's called cardiorespiratory fitness, and the best-known way to measure it is VO2 max, the most oxygen your body can use during hard exercise. In 2016 the American Heart Association said it should be treated as a clinical vital sign, right next to blood pressure.1 Here's what the research shows, and what you can do with it.
The Short Version
→ Low cardio fitness was tied to a mortality risk as large as, or larger than, smoking or diabetes in a study of 122,007 adults.2
→ Across 199 cohort studies, people with high fitness had about half the risk of dying during follow-up compared with people with low fitness.4
→ The biggest gain comes from moving out of the least-fit group. You don't need to be an athlete.1
→ Fitness is trainable. Steady cardio and interval training both raised VO2 max in controlled trials.7,8
What is cardio fitness, and how is it measured?
Cardiorespiratory fitness is how well your heart, lungs, blood vessels and muscles work together to deliver and use oxygen. It's usually reported as VO2 max (milliliters of oxygen per kilogram of body weight per minute) or as METs, where 1 MET is the energy you burn sitting quietly.
The gold standard is a treadmill or bike test with a mask that measures your breathing. A standard exercise treadmill test can also estimate it, and many smartwatches now give a VO2 max estimate. Watch numbers are rough, but they're useful for tracking your own trend over time.
What the research shows
1. Low fitness carries as much risk as the risk factors we already track
Cleveland Clinic researchers looked back at 122,007 adults who had treadmill stress tests and followed them for a median of 8.4 years. People in the elite fitness group had an 80% lower risk of death than people in the lowest group. The added risk from low fitness was as large as or larger than the risk tied to smoking, diabetes or coronary artery disease. There was no point where more fitness stopped helping.2 This was an observational study, so it shows a strong link, not proof of cause and effect.
2. Every step up in fitness counts
A 2009 meta-analysis in JAMA pooled 33 studies of healthy men and women. Each 1-MET higher level of fitness was associated with a 13% lower risk of death from any cause and a 15% lower risk of heart disease events.3
A 2024 review in the British Journal of Sports Medicine looked at the whole body of evidence: meta-analyses covering 199 cohort studies and more than 20.9 million observations. High fitness versus low fitness was linked with a 53% lower risk of death. Each 1-MET increase was linked with an 11% to 17% lower risk of death and an 18% lower risk of heart failure.4 The authors rated the certainty of the evidence as very low to moderate, which is typical for observational data, but the findings were consistent across populations.
3. The biggest payoff is at the bottom, not the top
The American Heart Association's scientific statement makes a point that matters for most people: the greatest drop in risk is seen when someone moves from the least-fit group (roughly under 5 METs) to the next group up (roughly 5 to 7 METs). In their words, "one need not have the fitness level of an elite athlete" to benefit.1 In 2024 the same group of researchers reviewed the newer evidence and came to the same conclusion: fitness should be a routine measurement in every health care setting.5
4. Fitness is trainable, and you have options
A meta-analysis of 28 controlled trials in healthy young and middle-aged adults found that steady endurance training raised VO2 max by 4.9 mL/kg/min and high-intensity interval training (HIIT) raised it by 5.5 mL/kg/min compared with controls.7 That works out to roughly 1.4 to 1.6 METs, the same size of change linked with lower risk in the studies above.
For women specifically, a 2023 meta-analysis found steady moderate-to-vigorous cardio and HIIT were equally effective for raising VO2 max, and training more sessions per week led to bigger gains with both.8 The takeaway: pick the style you'll actually keep doing.
5. Even short bursts in daily life may matter
A 2024 UK Biobank study tracked about 22,000 adults who didn't exercise in their leisure time, using wrist activity trackers. Women who got a median of about 3.4 minutes a day of short, vigorous bursts during normal life, like fast stair climbing, carrying heavy groceries or power walking uphill, had a 45% lower risk of major cardiovascular events and a 67% lower risk of heart failure. The link was much weaker in men.9 This was observational, so it can't prove the bursts caused the benefit, but it's a good reason to take the stairs.
How much is enough?
The U.S. Physical Activity Guidelines recommend 150 to 300 minutes a week of moderate aerobic activity, or 75 to 150 minutes of vigorous activity, plus muscle-strengthening work on 2 or more days a week. The guidelines also note that short bouts count, and the people who are least active today gain the most from small increases.6
Here in the Inland Northwest, that can look like brisk walks on the Centennial Trail, hiking the hills around Liberty Lake, or snowshoeing and cross-country skiing once winter sets in. When the weather turns, a treadmill, bike or stairwell works just as well.
What you can do
→ Get a baseline. Ask your provider whether a fitness estimate makes sense for you, or track the VO2 max estimate on your watch. Look at the trend, not one number.
→ Build a base. Work toward 150 minutes a week of brisk walking, hiking, cycling or swimming, where you can talk but not sing.
→ Add one harder session a week. A few rounds of a few minutes at a hard effort with easy recovery in between, once your base is in place.
→ Use everyday bursts. Take the stairs fast, carry the groceries, walk the hill.
→ Keep lifting. Two strength days a week protect muscle and make cardio easier.
→ Check in first if you've been inactive or have chest pain, shortness of breath, heart disease or diabetes. Talk with your provider before starting vigorous exercise.
The bottom line
Your cardio fitness says a lot about your long-term health, and unlike your age or your genes, you can change it. The research is clear that you don't need to become a marathoner. Moving from "not much" to "regular" is where most of the benefit is. If you want to know where you stand, a physician-led checkup is a good place to start.
Dr. Cody Belkoff, DO is a physician at Prime Body Solutions in Liberty Lake, WA, focused on preventive health, metabolic health and longevity for adults across the Inland Northwest.
Educational content only, not medical advice. Talk with your provider before starting a new exercise program, especially if you have a heart condition or other health concerns.
References
- Ross R, Blair SN, Arena R, et al. Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign. A scientific statement from the American Heart Association. Circulation. 2016;134(24):e653–e699. doi:10.1161/CIR.0000000000000461
- Mandsager K, Harb S, Cremer P, et al. Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Netw Open. 2018;1(6):e183605. (Retrospective observational cohort.) doi:10.1001/jamanetworkopen.2018.3605
- Kodama S, Saito K, Tanaka S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: a meta-analysis. JAMA. 2009;301(19):2024–2035. doi:10.1001/jama.2009.681
- Lang JJ, Prince SA, Merucci K, et al. Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies. Br J Sports Med. 2024. doi:10.1136/bjsports-2023-107849
- Ross R, Arena R, Myers J, Kokkinos P, Kaminsky LA. Update to the 2016 American Heart Association cardiorespiratory fitness statement. Prog Cardiovasc Dis. 2024. doi:10.1016/j.pcad.2024.02.003
- Piercy KL, Troiano RP, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320(19):2020–2028. doi:10.1001/jama.2018.14854
- Milanović Z, Sporiš G, Weston M. Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: a systematic review and meta-analysis of controlled trials. Sports Med. 2015;45(10):1469–1481. doi:10.1007/s40279-015-0365-0
- Lindner R, Selva Raj I, Yang A, et al. Moderate to vigorous-intensity continuous training versus high-intensity interval training for improving VO2max in women: a systematic review and meta-analysis. Int J Sports Med. 2023;44(7):484–495. doi:10.1055/a-2044-8952
- Stamatakis E, et al. Device-measured vigorous intermittent lifestyle physical activity (VILPA) and major adverse cardiovascular events: evidence of sex differences. Br J Sports Med. 2024. (Observational cohort, UK Biobank.) doi:10.1136/bjsports-2024-108484
