The single-leg stance test measures balance: the person stands on one leg, lifts the other, keeps their arms at their sides, and tries to hold that position for ten seconds without support and without the raised foot touching the ground.
A study published in the British Journal of Sports Medicine in 2022 followed 1,702 adults aged 51 to 75 in Brazil for a median of seven years. The adjusted hazard ratio for all-cause mortality was 1.84 among people who couldn't hold the stance for ten seconds, compared with those who could, after accounting for age, sex, BMI, and other health factors. During follow-up, 17.5% of those who failed the test died, compared with 4.6% of those who passed; these percentages are not an individual prognosis.
Standing on one leg requires vision, the vestibular system, neural control, muscles and joints to work together. The observational study did not establish which of these factors explained the link with mortality, or whether a change in balance appears before other changes in physical function.
The result is also heavily shaped by protocol: whether the eyes are open or closed, which leg is standing, hard floor versus carpet, shoes on or off. A single home attempt isn't directly comparable to a number from a specific study.