As you get older, a few blood values slowly shift: your testosterone drops, your blood fats change and your muscle retention needs more attention. Anyone who wants to age fit keeps an eye mainly on their hormones, their heart and blood vessels and their metabolic health. This is the guide that lists those values.
I think ageing is no reason to give in. With the right measurements you see early where you can adjust, instead of waiting.
What changes in your blood as you age?
Over the years your hormone balance, your fat metabolism and your recovery capacity change. Your testosterone drops gradually, your blood fats often become less favourable and your muscle mass declines if you do nothing about it. Those shifts run creeping, which is exactly what makes them interesting to measure.
The good thing is that much of this is adjustable. Strength training, nutrition and sleep do more than you think, and your blood shows whether it works.
Important is that you do not have to track everything at once. A handful of core values, measured yearly, already gives you a reliable trend to steer on. That way ageing becomes something you actively guide instead of passively undergo. The rest of this guide walks through those core values system by system.
The most important longevity blood values
For healthy ageing, your hormones, your heart and blood vessels, your metabolic health and your vitamins count most. The table below links each area to the markers that say the most about it.
| Area | Core markers | Why over the years |
|---|---|---|
| Hormones | Testosterone, free testosterone, SHBG | Drop gradually from your forties |
| Heart and vessels | ApoB, cholesterol, blood pressure | Risk rises with age |
| Metabolic health | HbA1c, fasting insulin | Insulin sensitivity often declines |
| Muscle retention | Vitamin D, protein status | Sarcopenia lurks |
If you want the explanation per marker, our biomarker guide for athletes is your reference.
Hormones: testosterone and the age decline
Your testosterone drops gradually from around your forties, by a little under one percent per year on average. A long-running study in men found a decline of around 0.8 percent per year (Feldman, 2002). That sounds small, but over a decade it adds up.
For an athlete this matters because testosterone supports your recovery and muscle retention. The decline itself need not be a problem, but it is good to know your baseline. With a known starting point you can later tell a normal age trend apart from something that deserves a closer look.
You read the full explanation in testosterone and ageing and in the pillar testosterone: symptoms and blood values.
Heart and vessels: ApoB and blood pressure
Your heart risk rises with age, and your blood fats are a key in that. ApoB counts the harmful particles in your blood and predicts risk more accurately than cholesterol alone (Sniderman, 2019). Together with your blood pressure this forms the base of your cardiovascular longevity.
Good fitness lowers your risk, but does not automatically remove it. That is why these values stay important for athletes too.
Dig into our guide cholesterol and your heart values.
Muscle retention and sarcopenia
Over the years you lose muscle mass if you do nothing about it, a process called sarcopenia. Muscle retention is one of the strongest pillars of healthy ageing, because it keeps your strength, your metabolism and your independence up. Strength training and enough protein are your main levers here.
Your blood supports this indirectly. A good vitamin D status helps your muscle function, and your hormone balance partly determines how well your muscles recover.
Read more about the role of micronutrients in vitamins and minerals for athletes.
Metabolic health stays the base
As you age, your insulin sensitivity often declines, even if you train. That is why HbA1c and fasting insulin stay core markers for your longevity. They show early whether your sugar balance is shifting, often years before your glucose deviates.
This is the foundation the rest rests on. A healthy metabolism makes the other improvements easier.
You find the full explanation in our guide measuring metabolic health. If your thyroid plays a role in your energy, also look at thyroid and metabolism.
Vitamins and bones over the years
Your bone density and your vitamin D status need more attention over the years. Vitamin D supports your muscle function and your bones, and older athletes in particular risk a low status in winter. A deficiency can subtly slow your recovery and your strength.
Your vitamin B12 and your iron also deserve attention, because uptake can change with age. Measuring prevents a creeping deficiency from staying unnoticed.
Read the details in our vitamin and mineral guide.
How often do you measure as you age?
From your forties an annual measurement of your core values is a reasonable rule of thumb, certainly if you want to stay fit. That way you build a trend and see shifts early. With a deviation your doctor follows your values more often.
Compose your own panel through our custom blood test, or start with the broad 360 Health blood test that combines most of these values.
My advice: measure to steer, not to worry. A trend over the years is your best compass for healthy ageing.
Blood pressure: the underrated longevity marker
Blood pressure is one of the most underrated predictors of your long-term health. A too-high blood pressure strains your heart and blood vessels for years without you feeling anything, and the risk rises gradually with age. Precisely because it goes creeping, regular measuring is so valuable.
For an athlete this matters because good fitness does not always prevent high blood pressure. Genetic predisposition, salt, stress and sleep all play a part.
The good thing is that lifestyle has a lot of influence here. Movement, weight management and less salt can lower your blood pressure measurably.
Combine your blood pressure with your blood fats for a complete cardiovascular picture. Together they tell you more than each apart.
Kidneys and liver over the years
Your kidney and liver function change slowly with age, and it pays to keep an eye on them. The eGFR estimates your kidney function, while liver values such as ALT say something about fat accumulation and your metabolism. In athletes the interpretation in particular needs attention, because muscle mass and training affect your values.
A raised creatinine in a muscular athlete, for example, does not automatically mean a kidney problem. The context decides the meaning.
Your liver values too can rise temporarily after a hard session or after alcohol. A one-off rise therefore says less than a trend at rest.
Read more about these values in our biomarker guide for athletes.
Sleep, stress and cortisol over the years
As you age, your sleep often changes: you sleep lighter and your recovery takes more time. Poor sleep disturbs your hormone balance, and a disturbed hormone balance worsens your sleep, a vicious circle that can grow stronger over the years. Cortisol, your main stress hormone, plays a central role in this.
For an athlete this counts double, because recovery is the base of your progress. If your sleep and stress get out of balance, you feel it in your training and your energy.
You measure cortisol at a fixed moment, ideally in the morning, because it has a clear daily rhythm. A one-off value says less than a pattern over the day.
Also read what poor sleep does to your hormones in sleep and your hormones. Sleep may well be the most underrated longevity pillar.
Bone density and your fracture risk
Over the years your bone density declines, and that raises your fracture risk in the long run. Strength training and enough vitamin D and protein help keep your bones strong. Your blood supports this indirectly, mainly through your vitamin D status.
For active athletes this is good news, because load actually stimulates your bones to stay strong. Movement is one of your most powerful levers here.
A low vitamin D status undermines both your muscle function and your bones. That is why measuring in winter, your lowest point of the year, is extra useful.
You read the full explanation about vitamin D in our vitamin and mineral guide.
Inflammation and your biological age
Low-grade inflammation rises with age in many people, a phenomenon sometimes called inflammaging. A chronically slightly raised inflammation value can slow your recovery in the background and is linked to various age-related risks. CRP is the best-known marker of this.
The distinction between a temporary and a chronic rise is important. A high CRP right after a hard session is normal, while a persistently raised value at rest deserves more attention.
Lifestyle has a lot of influence here. Nutrition, sleep, movement and body composition steer your inflammation level.
So measure at rest and follow the trend. A deviating value you discuss with your doctor.
Common mistakes with longevity testing
The biggest gain often sits in avoiding a few standard mistakes. Anyone who tracks their values over the years usually runs into the same traps.
The first mistake is only starting to measure once there are complaints. A baseline at forty in particular makes later changes much easier to read.
The second mistake is wanting to optimise everything at once. A few core values you track consistently say more than a one-off mountain of numbers.
The third mistake is using age as an excuse. Part of the decline belongs to ageing, but a large part can be influenced with lifestyle.
Frequently asked questions
The questions I get back most from athletes who want to stay fit after forty.
Which blood values matter most after forty? Your hormones, your blood fats such as ApoB, your metabolic markers and your vitamin D form a strong base. Which exactly you choose depends on your goal and your complaints.
Does my testosterone drop anyway as I age? On average testosterone drops gradually with age, but lifestyle plays a big role. Sleep, strength training and body composition affect your level too.
Can I counter ageing with my blood values? You cannot stop ageing, but you can adjust early. Your blood shows where lifestyle or guidance is useful, in consultation with your doctor.
References
- Feldman HA, Longcope C, Derby CA, et al. Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study. Journal of Clinical Endocrinology and Metabolism. 2002;87:589-598. PMID: 11836290.
- Sniderman AD, Thanassoulis G, Glavinovic T, et al. Apolipoprotein B Particles and Cardiovascular Disease: A Narrative Review. JAMA Cardiology. 2019. PMID: 31642874.
- Gezondheidsraad. Physical activity guidelines and healthy ageing. Accessed 2026.
Disclaimer
Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.
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