Medically reviewed by: Alena Golhova, PharmDr. — Biochemistry, Univerzita Komenského v Bratislave

Last reviewed: 2026-10-16

The most useful longevity biomarkers are ones you can measure repeatedly and that respond to something you can do. Grip strength, walking speed and one-legged balance need no laboratory and predicted survival in large cohort studies. Two blood tests, hs-CRP and IGF-1, add information but need careful interpretation. Epigenetic clocks get the most attention and are the hardest to act on.

This guide separates the markers worth tracking from the ones worth reading about. All the survival figures below come from observational studies: they show associations, not that changing the marker changes your lifespan.

Key points

Grip strength: each 5 kg lower grip was associated with a hazard ratio of 1.16 for death in 139,691 adults
Walking speed: each 0.1 m/s faster was associated with a hazard ratio of 0.88 for death in 34,485 adults aged 65 and over
Balance: adults aged 51 to 75 who could not stand on one leg for 10 seconds had a hazard ratio of 1.84 for death
hs-CRP should be measured twice, about two weeks apart, and not during an infection
Discuss blood results, especially IGF-1, with your doctor rather than against a number from an article

What makes a biomarker worth tracking?

Is it predictive? Is it associated with later health outcomes in large studies?
Can you measure it repeatedly? Cost and access decide whether you get a trend or a single number.
Can you move it? A marker that responds to nothing you can do is of academic interest only.

Three tests you can do at home

Grip strength

Grip strength is measured with a hand dynamometer. In the PURE study, which followed 139,691 adults aged 35 to 70 in 17 countries for a median of four years, every 5 kg reduction in grip strength was associated with a hazard ratio of 1.16 for death from any cause. Grip strength predicted all-cause and cardiovascular death better than systolic blood pressure. The authors noted that it remains to be tested whether improving strength reduces mortality.

Grip strength is harder to change than you might expect. A 2019 meta-analysis of exercise trials in 3,018 healthy older adults found only a small effect on grip strength. Task-specific and multimodal training were the approaches most likely to improve it.

Walking speed

A 2011 pooled analysis of nine cohorts with 34,485 adults aged 65 and over found that each 0.1 m/s faster usual walking speed was associated with a hazard ratio of 0.88 for death. At age 75, predicted 10-year survival ranged from 19% to 87% in men and from 35% to 91% in women, depending on walking speed. You need only a stopwatch and a marked distance.

In a 2021 meta-analysis of randomised trials in adults aged 65 and over with frailty or sarcopenia, resistance training programmes lasting 10 to 48 weeks improved walking speed (effect size 0.75) and grip strength (effect size 0.51). Those trials were in frail older adults; healthy people may see smaller changes.

Standing balance

In a cohort of 1,702 adults aged 51 to 75, the 20.4% who could not stand on one leg for 10 seconds had a hazard ratio of 1.84 for death over a median of seven years, after adjusting for age, sex, body mass index and other conditions. The authors note that recent falls and physical activity were not accounted for.

Two blood markers

hs-CRP (high-sensitivity C-reactive protein)

hs-CRP rises with infection and inflammation, so a single reading says little. A 2003 statement from the American Heart Association and the US Centers for Disease Control and Prevention recommends measuring it twice, ideally two weeks apart, and repeating any result above 10 mg/L after two weeks once infection or inflammation has been looked for. The same statement grouped results as below 1 mg/L, 1 to 3 mg/L and above 3 mg/L, which correspond roughly to the lower, middle and upper thirds of the adult population. Body weight matters: weight loss is associated with lower hs-CRP.

IGF-1 (insulin-like growth factor 1)

With IGF-1, more is not better. A 2022 meta-analysis of cohort studies with 30,876 adults found a U-shaped relationship with mortality: compared with mid-range levels, low IGF-1 was associated with a hazard ratio of 1.33 and high IGF-1 with 1.23. The lowest mortality was seen between 120 and 160 ng/ml in that analysis; interpret your own result with your doctor. Higher intakes of protein, carbohydrates and dairy were associated with higher IGF-1.

Epigenetic clocks: interesting, hard to act on

Epigenetic clocks estimate biological ageing from DNA methylation in a blood sample. DunedinPACE, published in 2022, was built from two decades of follow-up of the Dunedin birth cohort and showed high test-retest reliability; it was associated with disease, disability and death.

Many other clocks are noisier. A 2022 study found that technical noise alone produced differences of up to 9 years between repeat measurements of the same samples for six widely used clocks. In practice, a poor score leads back to the exercise, sleep and diet advice that applies anyway.

Comparing the markers

Marker	Where	What can move it
Grip strength	Home or gym, hand dynamometer	Training, with a small effect in healthy older adults
Walking speed	Home, stopwatch	Resistance training (shown in frail older adults)
One-leg stance	Home	Not tested in the studies cited here
hs-CRP	Standard blood test	Body weight
IGF-1	Specialist blood test	Diet, interpreted with your doctor
Epigenetic clock	Commercial test	Unclear

Why chasing the ultimate test backfires

Ageing is not a single process, and no single number captures it. A cheap test you can repeat every month gives you a trend; an expensive test you take once a year gives you a snapshot that is hard to interpret.

Frequently asked questions

Which biomarker should I start with?
Walking speed. It needs only a stopwatch, predicted survival in a pooled analysis of 34,485 older adults, and responded to resistance training in trials in frail older adults.

How often should I measure hs-CRP?
Twice, about two weeks apart, when you are well, and use the average.

Are epigenetic age tests worth the money?
Not as a basis for decisions. Technical noise can shift results by up to 9 years between repeat measurements for some clocks.

What does a high hs-CRP mean?
On its own, little. A result above 10 mg/L usually points to infection or inflammation and should be repeated after two weeks.

Can I improve these markers?
Partly. Resistance training improved walking speed and grip strength in trials in frail older adults; in healthy older adults the effect on grip strength was small.

Top longevity biomarkers: evidence-based guide to a healthier life