Published June 2026
What are physical tests for biological health?
Physical tests for biological health are measurable, repeatable assessments of how well your body is actually functioning — as distinct from how old your birth certificate says you are. They include blood biomarkers, physical performance tests, and body composition measures. Together, they give you a quantitative baseline you can track over time to see whether the lifestyle choices, supplements, and interventions you’re making are actually working.
This article is a companion to our guide on Biological Age Tests, which covers epigenetic clocks and DNA methylation-based testing. This article focuses on the physical and physiological tests — the ones you can get through your doctor, a fitness lab, or increasingly, at home — and what the current evidence says about which ones are worth prioritizing.
Why physical tests, not just epigenetic clocks?
Epigenetic clocks are scientifically fascinating. But a May 2026 perspective published in Live Science from researchers at Penn State noted that these tests are better suited to studying large populations than to tracking changes in individual health. A single test result tells you little; a trend over years tells you more; and even then, the clinical significance for any individual remains contested.
Physical and blood biomarker tests have a different kind of evidence behind them. Grip strength, for example, has been studied in hundreds of thousands of people across multiple continents. Its relationship to all-cause mortality is one of the most replicated findings in aging research. These tests are less glamorous than an epigenetic age estimate, but they are more actionable: you know what a low result means, you know what changes it, and you can measure again in six months to see if those changes worked.
The practical framework: start with the tests that are most predictive of serious outcomes, most modifiable through lifestyle, and most readily available. Add advanced testing once the basics are well-controlled.
Tier 1: The five tests to start with
If you do nothing else, these five cover the highest-yield ground. They can each be obtained through your primary care provider (PCP) or measured at home.
Blood pressure
Blood pressure sounds less sophisticated than a panel of novel biomarkers, but it is one of the most powerful longevity predictors in medicine. Years of elevated pressure damage arteries, the brain, kidneys, and heart before any symptoms appear. The American Heart Association (AHA) includes it as one of “Life’s Essential 8” health metrics for good reason.
Target: below 120/80 mmHg (millimeters of mercury). Sustained readings of 130/80 or above indicate elevated risk. Home monitoring with a validated cuff provides a more reliable picture than a single office reading. If your readings vary widely across the day, ask your doctor about 24-hour ambulatory monitoring.
Apolipoprotein B and Lipoprotein(a)
Standard cholesterol panels measure low-density lipoprotein (LDL) cholesterol, but LDL is a less precise predictor of cardiovascular risk than the number of atherogenic particles circulating in your blood. Apolipoprotein B (ApoB) measures that particle count directly — each LDL, very low-density lipoprotein (VLDL), and remnant particle carries exactly one ApoB molecule. Most preventive cardiologists now consider ApoB one of the most accurate early predictors of cardiovascular risk.
Lipoprotein(a) [Lp(a)] is a genetically determined lipid particle that is largely independent of diet and lifestyle. It is a major independent risk factor for heart disease and stroke, and most people have never had it tested. Unlike ApoB, Lp(a) typically only needs to be measured once — if elevated, it informs lifetime cardiovascular risk management.
Both tests are increasingly available through standard labs; ask your PCP specifically, as neither appears on a typical lipid panel.
HbA1c and fasting insulin
Hemoglobin A1c (HbA1c) reflects average blood glucose over the prior two to three months. It is the standard screening test for diabetes and pre-diabetes — but it also reflects metabolic health more broadly. Elevated HbA1c is associated with higher risk of cardiovascular disease, cognitive decline, and all-cause mortality, even at levels that don’t meet the clinical threshold for diabetes.
HbA1c alone, however, can miss early insulin resistance — the state in which the body produces enough insulin to keep glucose in the normal range, but only by working much harder than it should. Fasting insulin, measured alongside fasting glucose, allows calculation of the homeostatic model assessment of insulin resistance (HOMA-IR), a more sensitive early warning sign of metabolic dysfunction.
If your HbA1c is normal but your fasting insulin is above 10 µIU/mL (microinternational units per milliliter), that is worth paying attention to and discussing with your doctor.
Body composition
Body weight alone tells you almost nothing useful. The ratio of lean muscle mass to body fat — and where that fat is distributed — tells you a great deal. Excess visceral fat (the fat stored around internal organs, not the fat you can pinch) is independently associated with insulin resistance, inflammation, cardiovascular disease, and cognitive decline.
The most clinically informative body composition measure is a dual-energy X-ray absorptiometry (DEXA) scan, which separately measures fat mass, lean muscle mass, and bone density. These are available at many radiology clinics and fitness centers for approximately $50–$150. Smart scales using bioelectrical impedance analysis (BIA) are a practical at-home alternative for tracking trends, though less precise than DEXA. For at-home options, see our review of Health Monitoring Devices.
Grip strength
Grip strength is one of the most robustly studied physical performance markers in aging research. A 2015 study published in The Lancet (Leong et al.) followed 140,000 adults across 17 countries and found that grip strength was a stronger predictor of cardiovascular death and all-cause mortality than systolic blood pressure. A 2023 study found it to be a proxy for whole-body muscle strength and a key indicator of sarcopenia — the age-related loss of muscle mass that is a primary driver of functional decline.
It is measured with a hand dynamometer (approximately $30–$50). General benchmarks for adults aged 40–65: above 40 kg for men, above 25 kg for women is considered good. Below 30 kg (men) or 20 kg (women) signals meaningful risk. Track the trend over time; a declining trajectory matters as much as the absolute number.
Tier 2: Adding a healthspan snapshot
Once the Tier 1 markers are measured and any concerning results addressed, these tests add meaningful depth.
VO2 max
VO2 max — the maximum volume of oxygen your body can use per kilogram of body weight per minute (mL/kg/min) — is arguably the single strongest predictor of long-term survival in healthy adults. A 2018 study in JAMA Network Open (Mandsager et al.) followed 122,007 patients for over a decade and found that those with the highest aerobic capacity had approximately a five-fold lower mortality risk compared to those with the lowest fitness. Each additional MET (metabolic equivalent of task) of cardiorespiratory fitness was associated with 13% lower mortality.
Lab measurement involves a graded exercise test on a treadmill or cycle with expired gas analysis — available at sports medicine clinics, university exercise labs, and many fitness centers. A practical estimate is also available from the Rockport Walking Test (a 1-mile timed walk), and modern wearables like Apple Watch, Garmin, and Whoop now provide VO2 max estimates of reasonable accuracy for tracking trends.
Age-adjusted VO2 max benchmarks vary, but for adults aged 40–65, a score above 40 mL/kg/min for men and above 35 mL/kg/min for women is associated with strong long-term outcomes. Scores below 25 (men) or 20 (women) indicate significantly elevated risk. For a deep dive, see our article on VO2 Max: Your Body’s Horsepower Rating.
High-sensitivity C-reactive protein
High-sensitivity C-reactive protein (hsCRP) is a marker of systemic inflammation — the low-grade, chronic background inflammation that is increasingly understood as a driver of cardiovascular disease, cancer, neurodegeneration, and accelerated aging. Unlike the standard CRP test used to detect acute illness, hsCRP is sensitive enough to detect the chronic inflammation associated with metabolic dysfunction and lifestyle factors.
A reading below 1.0 mg/L (milligrams per liter) is optimal. Between 1.0 and 3.0 is elevated but modest risk; above 3.0 is high risk. If your hsCRP is persistently elevated without an acute illness to explain it, it is a signal worth investigating with your doctor. Lifestyle factors with strong evidence for lowering hsCRP include regular aerobic exercise, dietary change (particularly reduction of ultra-processed foods), improved sleep, and weight loss. See also our article on Immunity Against Aging for the broader context on inflammation and healthspan.
Walking speed (gait speed)
Gait speed — how fast you walk — sounds almost too simple to be useful. But it is one of the most validated predictors of functional decline and mortality in adults over 40. A 2011 meta-analysis in JAMA pooled data from nine studies and found that gait speed predicted survival across all age groups studied.
The standard test is a timed 4-meter walk. A speed above 0.8 meters per second (m/s) is the threshold above which fall and frailty risk increases significantly. A speed above 1.2 m/s is associated with strong outcomes. You can measure this at home with a 13-foot tape measure and a stopwatch. It takes two minutes and costs nothing.
Resting heart rate and heart rate variability
Resting heart rate (RHR) reflects cardiovascular efficiency. A lower resting heart rate generally indicates a more efficient heart. An RHR consistently below 60 beats per minute (bpm) is associated with lower cardiovascular risk; above 80 bpm at rest is associated with meaningfully elevated risk, independent of other factors.
Heart rate variability (HRV) — the variation in time between successive heartbeats — is a measure of autonomic nervous system health and the body’s capacity to recover from stress. Higher HRV generally indicates better cardiovascular and metabolic health. Wearables like Oura Ring, Whoop, and Garmin devices track both metrics continuously and are among the more practical tools for monitoring these over time.
Bone density
Bone mineral density (BMD) is measured by a DEXA scan — the same scan used for body composition. Bone density peaks in your 30s and declines thereafter, accelerating particularly in women after menopause. Low BMD (osteopenia or osteoporosis) dramatically increases fracture risk — and a hip fracture in a person over 65 has roughly a 20–30% one-year mortality rate, making it one of the most consequential health events of later life.
The US Preventive Services Task Force (USPSTF) recommends bone density screening for women aged 65 and older, and earlier for women with risk factors. Men are screened less systematically; ask your PCP if a DEXA scan is appropriate for you. Bone density is highly modifiable through strength training, calcium and vitamin D adequacy, and in some cases medication.
Tier 3: Advanced testing worth considering
These tests are more specialized, but relevant for people who want a comprehensive picture or who have concerning results in the Tier 1 or 2 categories.
Organ function panel
A standard annual physical includes basic liver and kidney function tests, but a more thorough longevity panel adds cystatin C (a more sensitive measure of kidney filtration than standard creatinine), liver enzymes including gamma-glutamyl transferase (GGT) as a sensitive marker of metabolic and alcohol-related stress, and albumin as a marker of nutritional status and chronic illness.
Thyroid function
The thyroid regulates metabolism, energy, mood, cognition, and cardiovascular function. Thyroid-stimulating hormone (TSH) is the standard screening test, but a more complete panel adds free T3 (fT3) and free T4 (fT4), and anti-thyroid peroxidase (anti-TPO) antibodies if autoimmune thyroid disease is suspected. Subclinical thyroid dysfunction is common and often asymptomatic — and frequently missed by TSH alone.
Hormones
For adults in the 40–65 age range, hormone levels are increasingly clinically relevant. Testosterone (total and free) declines with age in both men and women and has measurable effects on muscle mass, bone density, cognition, mood, and cardiovascular risk. Dehydroepiandrosterone sulfate (DHEAS), estradiol, and sex hormone-binding globulin (SHBG) round out a useful hormonal picture. Testing is most meaningful when clinical symptoms are present, but knowing your baseline in your 40s gives you a reference point for tracking change.
Homocysteine
Homocysteine is an amino acid that, when elevated, is associated with increased risk of cardiovascular disease, stroke, and cognitive decline including Alzheimer’s disease. It is not part of a standard lipid or metabolic panel and is frequently overlooked. Elevated homocysteine often responds well to B vitamin supplementation (B6, B9 folate, B12), making it one of the more actionable markers in this list. Target: below 10 µmol/L (micromoles per liter); above 15 µmol/L is considered high risk.
Microbiome analysis
Your gut microbiome influences immune function, inflammation, metabolism, and — increasingly — cognitive health. Microbiome testing via stool analysis can identify dysbiosis (imbalance), low diversity, and the presence or absence of keystone bacterial species. The clinical interpretation of microbiome results is still maturing, but several services now offer actionable dietary and supplement recommendations based on your results. See our full review of Viome for one approach.
How to prioritize and what to do with results
The framework that makes the most practical sense for the 40–65 age group:
Start here if you’ve never tracked these markers: blood pressure, ApoB and Lp(a), HbA1c with fasting insulin, body composition, and grip strength. These five cover cardiovascular risk, metabolic health, and functional strength — the three domains responsible for the greatest share of preventable morbidity in midlife.
Add for a fuller picture: VO2 max, hsCRP, gait speed, and resting HRV. VO2 max in particular is worth prioritizing — the evidence for its predictive value and modifiability is exceptionally strong.
Discuss with your doctor before adding: bone density, thyroid, hormones, organ function panel, and homocysteine — these are valuable but most useful when interpreted in clinical context.
A biomarker is only useful if it changes what you do. The cycle is: measure, interpret in context, intervene, remeasure. Testing without follow-through is an expensive ritual. Testing with a plan — whether that’s changing your diet, adding resistance training, adjusting sleep, or working with a specialist — is one of the highest-leverage investments you can make in your healthspan.
For the full picture of where these tests fit in your preventive health strategy, start with Setting Your Health Baseline: The Basics.
Summary table: Physical tests for biological health
| Test | What it measures | How to get it | Retest frequency |
|---|---|---|---|
| Blood pressure | Cardiovascular strain | Home monitor or PCP | Monthly (home) |
| ApoB | Atherogenic particle count | Blood draw via PCP/lab | Every 6–12 months |
| Lp(a) | Genetic cardiovascular risk | Blood draw via PCP/lab | Once (unless indicated) |
| HbA1c + fasting insulin | Metabolic health, insulin resistance | Blood draw via PCP/lab | Every 6–12 months |
| Body composition (DEXA) | Fat mass, muscle mass, bone density | Radiology clinic or fitness center | Annually |
| Grip strength | Whole-body muscular strength | Hand dynamometer (~$30) | Every 3–6 months |
| VO2 max | Cardiorespiratory fitness | Exercise lab or wearable | Annually |
| hsCRP | Systemic inflammation | Blood draw via PCP/lab | Every 6–12 months |
| Gait speed | Mobility and fall risk | 4-meter timed walk (free) | Every 6–12 months |
| Resting HR / HRV | Cardiovascular efficiency, recovery | Wearable device | Continuous |
| Bone mineral density | Osteoporosis risk | DEXA scan | Every 1–2 years |
| Homocysteine | Cardiovascular and cognitive risk | Blood draw via PCP/lab | Annually |
| Thyroid panel | Metabolic and endocrine function | Blood draw via PCP/lab | Annually |
| Hormones (testosterone, DHEAS) | Hormonal health and aging | Blood draw via PCP/lab | Annually |
| Microbiome | Gut health and immune balance | At-home stool test | Annually |
Frequently asked questions
What physical tests best predict longevity? The strongest predictors of all-cause mortality in adults are VO2 max, grip strength, blood pressure, ApoB, and HbA1c with fasting insulin. These five, taken together, give a comprehensive picture of cardiovascular, metabolic, and functional health — the three domains most responsible for premature death and disability in the 40–65 age group.
Can I measure my biological health at home? Several key markers are practical to measure at home: blood pressure with a validated cuff, grip strength with a hand dynamometer, gait speed with a tape measure and stopwatch, and resting heart rate and heart rate variability (HRV) with a consumer wearable. Blood biomarkers like ApoB, HbA1c, and hsCRP require a blood draw, typically through your PCP or a direct-to-consumer lab service.
How often should I retest my biological health markers? Most blood biomarkers are worth retesting every 6–12 months while you are actively making lifestyle changes; annually once your numbers are stable. Physical performance markers like grip strength and gait speed can be reassessed every 3–6 months. VO2 max and body composition are most useful measured annually. See the summary table above for a full breakdown.
What is the difference between biological age tests and physical health tests? Biological age tests — primarily epigenetic clocks based on DNA methylation — attempt to estimate how old your cells are at the molecular level. Physical health tests measure how well specific body systems are currently functioning. Both are useful, but physical tests are generally more actionable: a low grip strength score has a clear intervention (resistance training), whereas an elevated epigenetic age score is harder to translate into a specific next step. For more on epigenetic testing, see our article on Biological Age Tests.
Sources
- Leong DP et al., “Prognostic value of grip strength” — The Lancet, 2015
- Mandsager K et al., “Association of cardiorespiratory fitness with long-term mortality” — JAMA Network Open, 2018
- Studenski S et al., “Gait speed and survival in older adults” — JAMA, 2011
- Sniderman AD et al., “ApoB as a marker of cardiovascular risk” — Journal of Clinical Lipidology, 2025
- American Heart Association — Life’s Essential 8
- DNAmFitAge — Aging (Albany NY), 2023
- ClinicalTrials.gov — grip strength and mortality
- Keep.Health — Biological Age Tests
- Keep.Health — VO2 Max: Your Body’s Horsepower Rating
- Keep.Health — Health Monitoring Devices
- Keep.Health — Setting Your Health Baseline: The Basics
