A simple 30-second sit-to-stand test that can predict how well you age

The aging of the global population is one of the major demographic challenges of the 21^st century. Advances in medicine and public health over recent decades have increased life expectancy. However, the real challenge lies in ensuring that these additional years are lived with independence and a good quality of life. In this context, muscle function plays a central role, often determining whether older adults remain independent or develop functional limitations and geriatric syndromes.

The musculoskeletal system is one of the most affected systems by aging. From the third decade of life, it begins to gradually decline, and this process accelerates significantly after the age of 60. Several biological changes contribute to this deterioration. Fast-twitch muscle fibers, which are responsible for generating rapid and powerful movements, progressively decrease in number and size. At the same time, the nervous system becomes less efficient at activating muscle fibers, and fat and connective tissue infiltration within the muscle increases. Altogether, these changes reduce the ability to generate force and move efficiently. Importantly, different studies have shown that muscle power declines earlier and faster than other components of the musculoskeletal system, with losses of around 2–3% per year, compared to 1.0–1.5% per year for muscle strength and about 0.5–1.0% per year for muscle mass.

Among the different components of muscle function, muscle power has emerged as a particularly important indicator of healthy aging. Muscle power refers to the ability to produce force quickly, combining both strength and velocity, and it is essential for daily movements such as walking and climbing stairs.

How can we measure muscle power in a simple way?

Traditionally, evaluating muscle power required expensive and sophisticated equipment, limiting its use in clinical practice. However, Alcazar et al. (1) developed a validated equation based on a simple functional test: the sit-to-stand (STS) test. In this test, a person is asked to stand up and sit down from a chair as many times as possible within 30 seconds, with arms crossed over the chest. Then, using the validated equation (or the POWERFRAIL app), which accounts for body mass, height, and the number of STS repetitions performed during the test, we can estimate the person’s muscle power. These values can then be normalized to body mass to obtain relative STS power.

Why should we use muscle power as a biomarker?

To better understand the role of muscle power in healthy aging, we analyzed data from 1,876 older adults aged 65 years and older from the Toledo Study for Healthy Aging, a large population-based cohort study conducted in Toledo, Spain. The study was made available online in the Journal of Sport and Health Science on August 13, 2025, and published in Volume 15 on December 01, 2026.

Using the 30-second STS test and Alcazar’s equation, we estimated each participant’s relative STS power. Based on previous research (2), we identified individuals with low relative STS power as those with values below 2.53 W/kg in men and 2.01 W/kg in women.

Falls and fractures

When we examined participants’ recent health history, clear differences emerged between individuals with normal and low relative STS power.

In men, low relative STS power was associated with a higher likelihood of previous all types of fractures and falls. In women, the pattern was slightly different. Those with low relative STS power showed a higher likelihood of previous hip fractures, and a trend was also observed for previous falls and all types of fractures.

Hospitalizations and mortality

During a follow-up period of 6 years, women with low relative STS power had a 29% higher risk of hospitalization, and they also tended to spend more days in the hospital compared with women with normal relative STS power. However, the most striking results were observed for mortality. Men with low relative STS power had a 57% higher risk of all-cause mortality compared with those with normal relative STS power. In women, the association was even stronger. Those with low relative STS power had more than double the risk of death (104% higher) during the follow-up period (9 years).

Conclusion

In just 30 seconds, a simple movement like standing up from a chair can reveal a person’s risk of falls, hospitalization, and even death. Muscle power is not only essential for maintaining independence, but also a powerful biomarker of how well we age. Measuring it is simple; its implications are profound.

Reference
DOI: https://doi.org/10.1016/j.jshs.2025.101080

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