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12. The Future of Longevity: What Clinical Trials Are Testing and What We Still Don’t Know
Predictors of longevity: what to measure and which values to monitor
Resting heart rate, blood pressure, waist circumference and the ability to climb stairs can tell us a great deal about health. Simple blood tests can add useful information. Tracking these measures over time helps us notice deterioration and take action. Such indicators are called prognostic factors.
For longevity, the most useful factors are those we can influence: fitness, not smoking, diet, sleep, blood pressure and metabolic health. Measurements help us see whether changes in habits or treatment are reflected in our results. [1]
Resting heart rate is associated with the risk of premature death
A persistently higher resting heart rate is associated with a higher risk of premature death. An analysis of 46 studies involving more than 1.2 million people found that each additional 10 beats per minute was associated with approximately 9% higher relative mortality risk. This is an association observed in populations, not a calculation of an individual's remaining years of life. [2]
The usual adult range is 60–100 beats per minute. This does not mean that a long-term resting rate of 95 has the same prognostic significance as 65. A rate of 80–90 is not a diagnosis in itself. A persistently higher rate is a reason to review fitness, sleep, stress and possible medical causes. Trained people may have a rate of 40–60 without symptoms. [2] [3]
Measure in the morning or at a similar time, after 5–10 minutes of rest. Use a blood pressure monitor, a watch or count your wrist pulse for a full minute. Follow the average over several days. Regular exercise often lowers resting heart rate, while fever, anaemia, thyroid problems or an abnormal heart rhythm may raise it. Medicines and training also affect the appropriate rate for an individual. [3]
Simple home measurements and their values
These are guide values for adults at rest. During treatment or with chronic illness, a clinician may set different targets. How you feel and whether your condition is changing also matter.
| What to measure | Guide value | What to notice |
|---|---|---|
| Resting heart rate | Usually 60–100/min; sometimes 40–60/min in trained people. | A persistent rate above 80–90 deserves attention. Discuss repeated readings above 100 at genuine rest, a newly irregular rhythm or a low rate with weakness with a clinician. [2] [3] |
| Blood pressure | Around 120/80 mmHg is generally favourable. An average home reading of 135/85 mmHg or higher reaches the threshold for high blood pressure. | Either the upper or the lower number can meet the threshold. Assess an average over several days, not just one reading. Treatment targets are individual. [4] |
| SpO₂ on a finger pulse oximeter | Usually 95–100% in a healthy person at ordinary altitude. | Repeatedly low or falling readings deserve attention. Seek urgent medical advice for a new fall to 92% or below. Significant breathlessness matters even at 99%. [5] |
| Waist-to-height ratio | A practical guide: keep your waist below half your height. At a height of 180 cm, that means below 90 cm. | This guide is used in adults with a BMI below 35. When overweight, monitor waist reduction alongside preservation of strength. Unintentional weight loss and increasing weakness need investigation. [6] |
SpO₂ of 99% is usually normal and does not explain every case of breathlessness
A finger oximeter estimates the oxygen saturation of haemoglobin in arterial blood. Haemoglobin is the protein in red blood cells that carries oxygen. A reading of 99% while breathing room air is usually normal. It does not, by itself, mean that oxygen is staying in the blood instead of reaching the tissues. [5]
An oximeter does not show how much haemoglobin you have, how much blood your heart pumps or how well your tissues use oxygen. Someone can therefore have a reading of 99% and still be breathless, for example because of anaemia, heart disease or poor fitness. Normal saturation does not rule out a health problem. [7]
Red blood cell flexibility and flow through the smallest vessels matter for tissue oxygen supply. But a reading of 99% cannot tell us whether cells are stiff or releasing oxygen poorly. SpO₂ does not measure cell flexibility or the quality of microcirculation. During oxygen treatment, saturation targets are set separately; this differs from a reading of 99% while breathing room air. [7]
Measure on a warm finger, at rest and without moving, following the device instructions. Wait for the reading to settle. Cold hands, poor circulation, nail polish, skin pigmentation and other factors can affect accuracy. Readings may be several percentage points out, sometimes more; 98% and 99% therefore usually do not represent a meaningful difference. [5]
For severe or sudden breathlessness, chest pain, blue lips or impaired consciousness, call your local emergency number (112 in the EU), regardless of the oximeter reading. With chronic lung disease, follow your clinician's individual plan and usual saturation values. A reading of 88% or below requires immediate medical attention. [5]
Walking and stairs as a practical fitness check
Notice whether you manage your usual route, a gentle hill or familiar stairs as well as a month ago. Track pace, the need to stop, breathlessness and the time it takes for breathing and pulse to settle. Compare the same activity under similar conditions.
Studies associate better fitness, strength and walking speed with better survival. Regular walking, appropriate endurance activity and strength training can improve these abilities. For more precise assessment, a professional exercise test or grip-strength measurement may be arranged. [8] [9] [10]
If an activity you previously managed suddenly causes breathlessness, investigate the cause even if SpO₂ is 99%. Do not test deterioration by forcing yourself up stairs. Symptoms should be assessed by a clinician.
Read article 11: movement, bones, joints, circulation and lymph →
Useful blood tests and their values
Depending on local availability, many tests can also be arranged privately. Check preparation requirements and choose tests according to your risk. Laboratory reference ranges and treatment targets may differ. Not all these tests are needed at every preventive check-up; hsCRP and fibrinogen, for example, should address a specific clinical question.
| Test | Guide values | What it means |
|---|---|---|
| Fasting glucose | Usually 3.9–5.5 mmol/L. Values of 5.6–6.9 warrant assessment; values of 7.0 or above require confirmation of suspected diabetes. | Shows blood sugar at the time of sampling. Diagnosis is not based solely on a random home reading. Some guidelines use a different lower threshold for prediabetes. [11] |
| HbA1c | In people without diabetes, below 5.7%, or below 39 mmol/mol, is commonly quoted. | Reflects average blood glucose over approximately 2–3 months. Diabetes treatment targets are individual. Anaemia may affect the result. [12] |
| Triglycerides | Usually below 1.7 mmol/L. | Often respond to activity, body weight, alcohol and excess energy or sugary drinks. [13] |
| LDL cholesterol | European guideline examples: below 2.6 mmol/L at moderate cardiovascular risk, below 1.8 at high risk and below 1.4 at very high risk. | At high and very high risk, a reduction of at least 50% from baseline is usually also sought. A clinician sets the target; a laboratory label of “normal” may not be enough. [27] |
| HDL cholesterol | Below approximately 1.0 mmol/L in men and 1.3 mmol/L in women is commonly considered low. A higher value does not automatically mean lower risk. | Assess alongside LDL and triglycerides. Even very high HDL does not automatically guarantee protection. [13] [14] |
| hsCRP | Below 1 mg/L: lower relative cardiovascular risk; 1–3: average; above 3: higher risk. | These bands are assessed outside acute infection. They do not determine overall risk by themselves. Marked or persistent elevation needs investigation. [15] This more sensitive CRP test assesses low levels of inflammation. |
| Fibrinogen | A common laboratory range is approximately 2–4 g/L. | A clotting protein that also rises with inflammation. The range is not a longevity target; high or very low results require explanation. [16] |
Blood lipids should be assessed together
A lipid profile includes LDL, HDL and triglycerides. ApoB can help assess the number of particles involved in fat deposition in artery walls. Total cholesterol/HDL, triglycerides/HDL and ApoB/ApoA1 ratios provide additional information. A favourable ratio does not cancel the risk of high LDL or ApoB. [17] [18]
A study of almost 1.5 million life-insurance applicants illustrated the relevance of ratios. Total cholesterol/HDL was the best single predictor of all-cause mortality among the lipid tests assessed, but its predictive ability was modest and varied with age and sex. It is not a universal “longevity number”. The triglycerides/HDL ratio also depends on whether the units are mmol/L or mg/dL. [14]
How haematocrit and fibrinogen affect blood flow
Haematocrit, part of a blood count, shows the proportion of blood volume occupied by red blood cells. Interpretation depends on sex and the laboratory range. A high value may reflect dehydration or excess red cells; a low value may reflect anaemia. With anaemia, saturation may be 99%, yet blood carries less oxygen overall because it contains less haemoglobin. [19] [7]
Rheology studies how blood flows. Flow depends partly on the number, flexibility and aggregation of blood cells and on plasma proteins. Fibrinogen affects both clotting and flow properties. Studies have found associations between higher fibrinogen, certain rheological measures and cardiovascular events or mortality. [20] [21]
The practical steps are not smoking, regular activity, breaking up prolonged sitting and addressing high blood pressure, blood sugar or persistent inflammation. The clinical benefit of specialised viscosity or microcirculation testing depends on the method and how the result changes management. An oximeter cannot replace these investigations.
Homocysteine and other tests when needed
Homocysteine may indicate difficulties processing certain substances in the body. It can rise with vitamin B12 or folate deficiency and reduced kidney function. If elevated, look for the cause and consider B12, folate, blood count and kidney function. Use the laboratory's own reference range. [22]
Treating a confirmed vitamin deficiency matters. However, in HOPE-2, lowering homocysteine with vitamins did not reduce the primary combined outcome of cardiovascular death, heart attack and stroke. A lower number is therefore not automatic proof of longer life. [23]
Creatinine with estimated filtration rate (eGFR), and urine albumin-to-creatinine ratio according to risk, help assess kidney function. Uric acid, liver tests or insulin tests can address specific questions. A long list of paid tests does not replace selecting investigations according to health needs. [24]
Everyday habits for healthier ageing
The Mediterranean dietary pattern has good research support. In more than 25,000 women followed for around 25 years, greater adherence was associated with lower mortality. In PREDIMED, people at high cardiovascular risk assigned to a Mediterranean diet supplemented with olive oil or nuts had fewer major cardiovascular events than the comparison group advised to follow a low-fat diet. [25] [26]
In practice, this means more vegetables, legumes, fruit, whole grains, nuts and fish, using olive oil, and less processed meat, sweets and sugary drinks. There is no need to start drinking alcohol for health. A simple weekly food record can show what has actually changed.
Not smoking, regular sleep, activity and maintaining strength also matter. Monitor function, pulse, blood pressure, waist size and blood results when appropriate. Mental well-being and social contact are important too. [1]
How to start without overcomplicating things
- For one week, record blood pressure and resting pulse morning and evening. Measure blood pressure seated after five minutes of rest, taking two readings about a minute apart.
- Measure your waist once a month. Notice how you manage ordinary walking and stairs. Use SpO₂ when needed and recommended, always considering symptoms.
- Review your latest blood results. Select missing tests according to age and risk; private testing may be available locally.
- Choose one or two habit changes and maintain them. Time follow-up blood tests according to the test; HbA1c reflects months, not yesterday's lunch.
- Address new symptoms or deterioration even when one number looks good. New breathlessness with SpO₂ of 99% still needs an explanation.
Frequently asked questions
Can these values tell me how many years I will live?
No. They help assess health risks and changes in those risks. They cannot calculate an individual's lifespan precisely.
My SpO₂ is 99%. Does that mean breathlessness is harmless?
No. Normal saturation does not rule out anaemia, heart disease or declining fitness. New breathlessness needs explanation; for sudden severe breathlessness, call your local emergency number (112 in the EU).
Do I need all the blood tests listed?
No. Selection depends on age, health, previous results and risk. Some tests are useful only when investigating a specific concern.
Can LDL be within the laboratory range but above my target?
Yes. Higher cardiovascular risk usually means a lower treatment target. The target depends on overall risk and treatment progress.
What should I monitor first?
Notice everyday function, record resting pulse and blood pressure when appropriate, and review previous results. Start with a sustainable habit change rather than buying every available test.
Sources and further reading
- Lloyd-Jones DM et al. (2022). Life's Essential 8: Updating and Enhancing the American Heart Association's Construct of Cardiovascular Health: A Presidential Advisory From the American Heart Association. PubMed 35766027
- Zhang D, Shen X, Qi X (2016). Resting heart rate and all-cause and cardiovascular mortality in the general population: a meta-analysis. PubMed 26598376
- MedlinePlus. Pulse. Source and explanation of values
- NHS. High blood pressure. Source and explanation of values
- MedlinePlus. Pulse Oximetry. Source and explanation of values
- NICE NG246. Identifying and assessing overweight obesity and central adiposity. Source and explanation of values
- O'Driscoll BR, Howard LS, Earis J, Mak V (2017). British Thoracic Society Guideline for oxygen use in adults in healthcare and emergency settings. PubMed 28883921
- Mandsager K, Harb S, Cremer P, Phelan D, Nissen SE, Jaber W (2018). Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing. PubMed 30646252
- Celis-Morales CA et al. (2018). Associations of grip strength with cardiovascular, respiratory, and cancer outcomes and all cause mortality: prospective cohort study of half a million UK Biobank participants. PubMed 29739772
- Studenski S et al. (2011). Gait speed and survival in older adults. PubMed 21205966
- MedlinePlus. Blood sugar test. Source and explanation of values
- MedlinePlus. Hemoglobin A1C (HbA1C) Test. Source and explanation of values
- MedlinePlus. Cholesterol Levels. Source and explanation of values
- Fulks M, Stout RL, Dolan VF (2009). Association of cholesterol, LDL, HDL, cholesterol/ HDL and triglyceride with all-cause mortality in life insurance applicants. PubMed 20666103
- MedlinePlus. C-reactive protein. Source and explanation of values
- MedlinePlus. Fibrinogen blood test. Source and explanation of values
- Soffer DE et al. (2024). Role of apolipoprotein B in the clinical management of cardiovascular risk in adults: An Expert Clinical Consensus from the National Lipid Association. PubMed 39256087
- Ding M et al. (2021). The association of apolipoproteins with later-life all-cause and cardiovascular mortality: a population-based study stratified by age. PubMed 34952923
- MedlinePlus. Hematocrit. Source and explanation of values
- Fibrinogen Studies Collaboration et al. (2005). Plasma fibrinogen level and the risk of major cardiovascular diseases and nonvascular mortality: an individual participant meta-analysis. PubMed 16219884
- Lowe GD, Lee AJ, Rumley A, Price JF, Fowkes FG (1997). Blood viscosity and risk of cardiovascular events: the Edinburgh Artery Study. PubMed 9012704
- MedlinePlus. Homocysteine Test. Source and explanation of values
- Lonn E et al. (2006). Homocysteine lowering with folic acid and B vitamins in vascular disease. PubMed 16531613
- Chronic Kidney Disease Prognosis Consortium et al. (2010). Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis. PubMed 20483451
- Ahmad S et al. (2024). Mediterranean Diet Adherence and Risk of All-Cause Mortality in Women. PubMed 38819819
- Estruch R et al. (2018). Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. PubMed 29897866
- ESC/EAS (2025): Focused Update of the 2019 Guidelines for the management of dyslipidaemias. European Heart Journal. Risk categories and LDL cholesterol targets.
A selection of scientific and healthcare sources, not a systematic review of all publications. Values are guides for adults; laboratory reference ranges and individual treatment targets may differ. This educational article does not replace medical assessment or individual treatment planning.
