“Vitality span” is one of those terms that sounds meaningful but doesn’t point to anything specific. A search of Europe PMC in October 2026 returned no research papers that use the term. It works as a marketing label, built to sell programs, supplements, and subscriptions by making you feel like you’re missing something a product can give you. The idea it’s pointing at is real – the difference between living longer and living well – but the packaging hides what the research actually measures.
The best-studied measurable proxy is VO2 max.
VO2 max – the maximum rate your body can use oxygen during intense exercise – is a strong predictor of death from any cause. An American Heart Association scientific statement concluded that cardiorespiratory fitness is potentially a stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes.[1] In 6,213 men referred for treadmill exercise testing, exercise capacity was a more powerful predictor of mortality than other established risk factors for cardiovascular disease, and each 1-MET increase in capacity was linked to a 12% improvement in survival.[2] In 122,007 patients, risk-adjusted mortality fell steadily as fitness rose with no observed upper limit of benefit; the fittest group had an adjusted hazard ratio of 0.20 compared with the least fit.[3] These studies used treadmill exercise capacity, which tracks VO2 max, in people referred for testing, so they show associations in clinical populations.
The Baltimore Longitudinal Study of Aging followed 810 healthy adults aged 21 to 87 for a median of 7.9 years and found that peak VO2 declined in every decade of adult life. The rate of decline accelerated from 3-6% per decade in the 20s and 30s to more than 20% per decade in the 70s and beyond, and it held across all quartiles of self-reported physical activity.[4] In that study, the decline in oxygen pulse (the oxygen used per heartbeat) mirrored the decline in peak VO2, while maximum heart rate fell by only 4-6% per decade.[4] So this decline isn’t something you can stop completely.
What you can influence is your starting point. A higher level at 45 gives you more room before you reach a level that limits what you can do, and because the decline accelerates with age, that cushion matters more later.
This is the thing “vitality span” is trying to describe but never defines: the point below which your aerobic capacity starts to limit your independence. The researchers behind the Baltimore study frame it the same way: the ability to function independently depends largely on keeping enough aerobic capacity to perform daily activities.[4] That isn’t a vague concept. It’s something you can measure, track, and improve. This post doesn’t give a single cutoff number, because the sources above don’t establish one.
VO2 max comes from two parts working together. The central part is your heart’s ability to deliver oxygen-rich blood. The peripheral part is your muscles’ ability to extract and use that oxygen. A review of the limiting factors concluded that oxygen delivery, not extraction by skeletal muscle, is the primary limit on VO2 max in healthy people, and that the rise in VO2 max with training comes mainly from an increase in maximal cardiac output.[5] Adaptations inside the muscle, such as more mitochondrial enzymes, matter most for sustaining submaximal effort, because they improve fat use and reduce lactic acid build-up at a given pace.[5]
For a 45-year-old who never built a strong aerobic base in their 20s and 30s, the window to improve isn’t closed. In a meta-analysis of 28 controlled trials in healthy adults aged 18-45, both continuous endurance training and high-intensity interval training raised VO2 max compared with no exercise, by about 4.9 and 5.5 mL/kg/min respectively, with somewhat larger gains in people with lower starting fitness and in longer programs.[6] In a meta-analysis of 41 trials of sedentary adults aged 60 and older, aerobic training raised VO2 max by about 3.8 mL/kg/min (16.3%) compared with controls, with greater gains in programs longer than 20 weeks and at intensities around 60% to under 70% of VO2 max.[7] Neither analysis centred on 45-year-olds, but together they cover adults both younger and older than that.
What does this actually look like? The WHO recommends 150-300 minutes of moderate-intensity aerobic activity a week, and defines moderate intensity as a 5 or 6 on a 0-10 scale of perceived exertion relative to your own capacity.[8] Four sessions a week of about 40 minutes adds up to that range: a stationary bike, rowing machine, incline treadmill, or a brisk outdoor walk. The meta-analysis above shows interval training raises VO2 max too,[6] so choose the version you will keep doing. Before a maximal test or hard exercise, check with a clinician if you have heart disease, symptoms such as chest pain or unusual breathlessness, or have been inactive for a long time.
The question “am I healthy for 40” is the wrong question. A better question is “how much aerobic capacity do I have now, and which way is it heading?” Because the decline accelerates with age,[4] the starting point you build now matters, and the research above shows you can still raise it.
Bettering Me’s take: vitality span is a marketing term. VO2 max is a physical measurement, and the best-studied proxy we found for what the term points at. If testing makes sense for you, a clinician can help you read the number. Build it while you still can.
A note on testing. A maximal cardiopulmonary exercise test (CPET) with gas exchange measurement – a gradually increasing workout on a treadmill or bike until you can’t continue, with a mask measuring your breath – measures VO2 max directly. The practical alternatives are estimates. A one-mile walk test, using time, heart rate, age, weight and sex, estimated VO2 max in 343 adults aged 30-69 with a correlation of 0.92-0.93 against treadmill-measured values.[9] Estimates from consumer wearables are less reliable for any one person: in a meta-analysis of 14 validation studies, devices using exercise-based algorithms had little average bias but wide limits of agreement of roughly -9.9 to +9.7 mL/kg/min, while algorithms based on resting data tended to overestimate VO2 max, and the authors concluded that the error at the individual level is large.[10] Estimates can still be useful for watching your own trend over time if you use the same method each time, but if you want one reliable number, a CPET is the way to get it.
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: https://doi.org/10.1161/CIR.0000000000000461
↑︎ Myers J, Prakash M, Froelicher V, et al. Exercise capacity and mortality among men referred for exercise testing. N Engl J Med. 2002;346(11):793-801. DOI: https://doi.org/10.1056/NEJMoa011858
↑︎ 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. DOI: https://doi.org/10.1001/jamanetworkopen.2018.3605
↑︎ Fleg JL, Morrell CH, Bos AG, et al. Accelerated longitudinal decline of aerobic capacity in healthy older adults. Circulation. 2005;112(5):674-682. DOI: https://doi.org/10.1161/CIRCULATIONAHA.105.545459
↑︎ Bassett DR, Howley ET. Limiting factors for maximum oxygen uptake and determinants of endurance performance. Med Sci Sports Exerc. 2000;32(1):70-84. DOI: https://doi.org/10.1097/00005768-200001000-00012
↑︎ Milanovic Z, Sporis 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: https://doi.org/10.1007/s40279-015-0365-0
↑︎ Huang G, Gibson CA, Tran ZV, Osness WH. Controlled endurance exercise training and VO2max changes in older adults: a meta-analysis. Prev Cardiol. 2005;8(4):217-225. DOI: https://doi.org/10.1111/j.0197-3118.2005.04324.x
↑︎ Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451-1462. DOI: https://doi.org/10.1136/bjsports-2020-102955
↑︎ Kline GM, Porcari JP, Hintermeister R, et al. Estimation of VO2max from a one-mile track walk, gender, age, and body weight. Med Sci Sports Exerc. 1987;19(3):253-259. DOI: https://doi.org/10.1249/00005768-198706000-00012
↑︎ Molina-Garcia P, Notbohm HL, Schumann M, et al. Validity of estimating the maximal oxygen consumption by consumer wearables: a systematic review with meta-analysis and expert statement of the INTERLIVE Network. Sports Med. 2022;52(7):1577-1597. DOI: https://doi.org/10.1007/s40279-021-01639-y
Kurt Greiner
Kurt is a digital strategist and IT professional blending emerging technology with practical application to help businesses and individuals streamline their digital presence. His current work focuses on the intersection of intentional living and technological resilience, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.
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