Functional tests for healthy aging

Aging biomarkers are measurable biological indicators used to quantify a person's "biological age," which reflects their cellular and physiological health rather than the chronological number of years they have been alive. These markers exist across multiple systems and scales in the body, ranging from molecular signatures such as DNA methylation patterns (often called epigenetic clocks), telomere shortening, and circulating inflammatory proteins to macroscopic functional metrics like grip strength and walking speed (which are the primary subject of this post). They are informative because they provide a concrete, real-time assessment of an individual's physiological decline and systemic resilience. Clinicians can use these biomarkers to predict overall life expectancy, identify early risks for age-related chronic diseases (such as cardiovascular disease or dementia), and objectively measure whether specific longevity interventions, diets, or lifestyle changes are succeeding at slowing the aging process.

Put simply, biological age can differ significantly from chronological age. Your mental and physical capabilities can be greater or less than a typical person of your age which portends for your overall health and longevity. In addition to those mentioned above, informative aging biomarkers also include physiological variables such as blood glucose levels, cardiovascular fitness (e.g. VO2max), blood cholesterol, BMI (or waist-to-hip ratio) WBC and RBC counts, lung function, etc. In particular VO2max (maximum rate of oxygen consumption during strenuous exercise) correlates with one's overall health and biological age. People with a high VO2max are physiologically younger and likely to live longer than those with a low VO2max. But VO2max is not easy to measure accurately at home (QH).

A recent article in The New York Times argues that simple functional tests that can show lifespan trajectory by capturing key "physical capacity" capabilities that matter for aging well: strength, power, cardiovascular fitness, balance, and flexibility. Importantly, these measures are proxies for real-life independence (e.g., getting on/off the floor, walking around a city, carrying groceries) and have been linked in research to longevity and independent living. And they are easy to measure at home.

The article emphasizes starting early (because strength and muscle mass naturally decline with age) but also stresses that meaningful improvements are possible even very late in life, including among people in their 90s, with even light activity. A low score can be improved by regular strength, conditioning, and balance training. In other words, it is never too late to improve your physical abilities with regular activity.

The article describes the following four simple functional tests:

1. Sitting-Rising Test (SRT)

To perform the Sitting-Rising Test, go from a standing position to sitting on the floor, then stand back up, using the least amount of support possible (see Video 1 for details). The test is scored on a 10-point scale: you start with five points for sitting down and five points for standing up, but subtract one point for every hand, knee, or other body part used for support, and a half-point if you lose your balance. Adults in their 30s and 40s should aim for a perfect 10, while an 8 is considered "very good shape" for those over 60. Physiologically, this movement is a compressed test of your lower-body strength, power, flexibility, and rapid postural control. In a 12-year study tracking over 4,000 adults aged 46 to 75, individuals who scored a 4 or below had death rates nearly four times higher than perfect scorers, driven largely by a significantly higher risk for dangerous falls.

Video 1. Demonstration of Sitting-Rising Test.

2. Walking Speed Assessment

For the walking speed assessment, measure a straight, flat 4-meter (about 13-foot) path and time how long it takes to walk that distance at your normal, everyday pace. People of all ages should aim for a walking speed of at least 1.2 meters per second, which means covering the distance in just over three seconds. While walking feels automatic, it physiologically measures your "systems integration" because it requires the complex, coordinated functioning of your cardiovascular, musculoskeletal, vestibular, sensory, and nervous systems. Because so many physical systems are involved, a slower-than-average gait serves as a powerful summary biomarker of physiological decline and is highly predictive of future disability, nursing home placement, and overall mortality.

3. Grip Strength Test

While clinics use a dynamometer to measure grip strength, you can test a proxy for this at home using the "farmer's carry" by walking for 60 seconds while holding a heavy weight in each hand. A 45-year-old man should aim to carry two 60-pound dumbbells, while a 45-year-old woman should aim for 40 pounds in each hand, with targets scaling down for ages 65 and 85. Physiologically, grip strength measures your neuromuscular function and serves as an indicator of how active you are in your daily life, predicting your ability to maintain independence with standard household tasks. Large epidemiological studies show that lower grip strength is directly related to a higher risk of all-cause mortality, as a weaker grip is a strong indicator of overall physical frailty and declining physiologic reserve. In one study, the authors argued that grip strength is a better predictor of mortality than other more widely used measures such as blood pressure (QH).

4. Single-Leg Stand

To assess your balance, stand on one leg and aim to hold the position for a minimum of 10 seconds on at least one side, optionally closing your eyes for an added challenge. Physiologically, this test captures how well your body integrates vestibular function, visual input, and neuromuscular lower-limb coordination. Because muscle strength and balance naturally decline with age, failing this test is a strong indicator of elevated fall risk—a major cause of injury and death in older adults. According to a 2022 study tracking adults aged 51 to 75, the 20 percent of individuals who were unable to hold the single-leg stand for 10 seconds had an 84 percent higher chance of dying within the next seven years.

Not mentioned in the article is one more test described in a previous post: Chair rise time "was measured with a stopwatch as the time taken to rise from a sitting to a standing position with straight back and legs and then to sit down again 10 complete times as fast as possible." The average time for the 10 chair rises was ~20 seconds for both middle-aged men and women, and slower times predicted higher mortality later in life.

In summary, these four aging tests -- sitting–rising (floor transfer), walking speed, grip strength, and single-leg balance -- are useful because they provide a low-cost, repeatable, real-world readout of functional aging: how well a person can generate force, move efficiently, maintain stability, and preserve independence in daily life. Unlike many lab-based biomarkers, they directly reflect the integrated performance of multiple organ systems (muscle, nerves, balance/vestibular function, cardiovascular capacity, joints, and brain-body coordination), which is why they correlate with outcomes like falls, disability, loss of independence, and mortality. Importantly, they also work well as trend markers; your aging trajectory is reflected in changes over months which can be clinically meaningful even if a single score is imperfect. 

These tests complement other aging biomarkers (such as epigenetic clocks, inflammatory markers, proteomics, metabolomics, and imaging-based measures) by adding the missing dimension of functional capacity. The molecular biomarkers may indicate biological aging processes or disease risk before symptoms appear, while the four physical tests show whether those processes are already affecting performance and resilience. Together, they furnish a more complete picture of aging by pairing mechanistic/biological signals with practical healthspan outcomes.