Key takeaways
A 2024 overview of 199 cohort studies found high versus low fitness was linked to 53% lower risk of death, and each 1-MET gain to 11 to 17% lower risk
A 2026 UK Biobank study found that improving estimated VO2max by 1 ml/kg/min per year was linked to lower cardiovascular risk, even after accounting for starting fitness
The evidence is still observational, so the newest studies strengthen the case for fitness but don't prove cause and effect on their own
The link between cardiorespiratory fitness and a longer life was established decades ago (see VO2max and longevity for the classic studies). So what have the latest papers added? Here's a summary of the most important recent studies, what they show, and where the gaps remain.
The newest studies at a glance
| Study | Design | Who | Main finding |
|---|---|---|---|
| Lang et al., Br J Sports Med, 2024 | Overview of 26 systematic reviews | 199 cohorts, 20.9 million observations | High vs low fitness: 53% lower risk of death; each 1 MET: 11–17% lower |
| Weeldreyer et al., Br J Sports Med, 2025 | Meta-analysis of 20 studies | ~399,000 observations | Fit people at any BMI had no significant excess risk; unfit people about 2–3 times the risk |
| López-Bueno et al., Eur J Prev Cardiol, 2026 | Cohort, fitness tested twice | 11,530 UK Biobank adults, 14 years | +1 ml/kg/min per year: 15% lower cardiovascular disease risk |
| Lundy et al., Sci Rep, 2026 | Cross-sectional survey | 340 multi-marathoners, 24 countries | VO2max above norms with a gentler age-related decline |
| Mandsager et al., JAMA Netw Open, 2018 (background) | Cohort | 122,007 treadmill tests | Least fit: about five times the risk of the elite; no upper limit |
2024: the biggest summary yet
Lang and colleagues pulled together every meta-analysis of cohort studies on fitness and health outcomes in adults published from 2002 to early 2024. The result is a review covering more than 20.9 million observations from 199 cohorts. Key numbers:
- All-cause mortality: high versus low fitness, hazard ratio 0.47, meaning about 53% lower risk.
- Dose-response: each 1-MET (3.5 ml/kg/min) higher fitness was linked to an 11–17% lower risk of death.
- Heart failure: high fitness was linked to 69% lower risk of developing it, and each 1 MET to 18% lower risk.
The authors found consistent evidence across general and clinical populations, though they rated the certainty of the evidence as very low to moderate, which is typical for observational data. If you don't know yours, our VO2max calculator is a good starting point.
2025: fitness versus fatness
Weeldreyer and colleagues pooled 20 studies (398,716 observations) that measured both fitness and BMI. Compared with fit people of normal weight, fit people with overweight or obesity had no statistically significant excess risk of dying, while unfit people in every weight group had roughly two to three times the risk. That doesn't make body fat irrelevant, but it suggests fitness explains much of the risk usually attributed to weight. We cover this in more detail in fit but fat and is VO2max overrated?.
2026: changing your fitness matters
Most fitness studies measure people once. López-Bueno and colleagues analysed 11,530 UK Biobank participants whose fitness was estimated twice from a submaximal cycle test, about four years apart, then followed them for a median of 14 years. After adjusting for starting fitness, genetics, BMI change and physical activity:
- Each +1 ml/kg/min per year improvement in estimated VO2max was linked to 15% lower risk of cardiovascular disease (HR 0.85) and lower cardiovascular mortality.
- Declines in fitness were linked to higher risk, in a roughly linear pattern with no obvious threshold.
This matters because it gets closer to the question people actually ask: if I get fitter, will my risk fall? It's still observational, but it supports the idea that improvement, not just starting level, counts. See how to improve VO2max and how fast you lose it.
2026: what lifelong endurance does to VO2max with age
Lundy and colleagues surveyed 340 multi-marathoners (average age 52, about 121 lifetime marathons). VO2max, estimated from their wearables, was well above population norms in every age group, often above the 95th percentile, and appeared to decline more gently with age. Older women showed the largest relative advantage.
Read this one carefully. The data were self-reported, VO2max came from watch estimates (see how accurate is watch VO2max?), the design was cross-sectional, and mortality was modelled from published estimates rather than measured. It's an encouraging picture of healthy ageing, not proof that marathons extend life. For more on age-related decline, see VO2max and ageing.
What's well established, and what isn't
| Claim | Status |
|---|---|
| Higher fitness is linked to lower risk of death | Well established, very consistent |
| The biggest gain comes from leaving the least-fit group | Well established |
| Fitness offsets much of the risk linked to high BMI | Supported by meta-analysis; debate continues |
| Improving fitness lowers your risk | Increasingly supported by repeat-measure cohorts |
| Very high fitness from decades of endurance adds extra years | Plausible, but data are limited and biased toward healthy volunteers |
What to do with this
- Measure a baseline, then retest once or twice a year. Our fitness age calculator turns a VO2max into an easy-to-grasp number.
- Aim for steady improvement: easy aerobic volume plus one interval session a week.
- Track other markers too. See which longevity biomarkers matter and our healthspan checklist.
If you have heart disease, symptoms on exertion or other health conditions, discuss your results and training plans with a doctor before ramping up intensity. Browse more studies on our research page.
Frequently asked questions
What is the latest research on VO2max and longevity?
Recent work includes a 2024 overview of meta-analyses covering 20.9 million observations, a 2025 meta-analysis on fitness and body weight, a 2026 UK Biobank study on changes in fitness and a 2026 study of multi-marathoners. All point the same way: higher and rising fitness is linked to lower risk.
Does improving VO2max later in life still help?
Studies that measured fitness twice suggest so. In UK Biobank, each 1 ml/kg/min per year improvement in estimated VO2max was linked to about 15% lower risk of cardiovascular disease, independent of starting fitness.
Do marathon runners live longer?
A 2026 study of 340 people who had run an average of 121 marathons found VO2max well above population norms with a gentler age-related decline. Mortality was estimated from models, not measured, and the data were self-reported, so it does not prove they live longer.
Is being fit more important than weight?
A 2025 meta-analysis of about 400,000 observations found that fit people with overweight or obesity had no significant excess risk of death compared with fit people of normal weight, while unfit people had about two to three times the risk.
Sources
- 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;58(10):556-566.
- Weeldreyer NR, De Guzman JC, Paterson C, et al. Cardiorespiratory fitness, body mass index and mortality: a systematic review and meta-analysis. Br J Sports Med, 2025;59(5):339-346.
- López-Bueno R, Andersen LL, Polo-López A, et al. Longitudinal changes of cardiorespiratory fitness are associated with cardiovascular disease and mortality: evidence from the UK Biobank. Eur J Prev Cardiol, 2026 (online ahead of print).
- Lundy L, Reilly RB, Fleming N. VO2max ageing and all cause mortality in a global cohort of multi marathoners. Sci Rep, 2026;16:21761.
- 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.