Do it the way the norms were measured
A score only compares with norms gathered the same way. Seat height changes how many chair stands you can do, a sit-and-reach box with your toes at 23 cm reads 3 cm lower than one at 26 cm, push-up counts depend on how deep each rep goes, and a 6-minute walk on a 10 m course came out about 50 m shorter than on a 30 m one. Each test page gives the set-up its norms used.
Sources 1, 2, 3, 4, 5, 6, 7
Expect some noise
Changes smaller than about 2 or 3 chair stands, 2 seconds on the timed up and go or 2 cm on the sit-and-reach may be everyday variation, and in one study of older adults a one-leg stand had to change by 24 seconds before the change was clearly real. A second 6-minute walk is usually about 26 m longer from practice alone. Retest the same way, and look at the trend over months rather than one result.
Sources 8, 9, 10, 11, 12, 13
Health links are associations
A stronger grip, a better score getting down to the floor and up, and holding a one-leg stand for 10 seconds all go with longer life in cohort studies. No trial has shown that raising a test score adds years. The habits that raise them have proven benefits of their own: in a review of 108 trials, exercise cut the rate of falls by about a quarter.
Sources 14, 15, 16, 17, 18
Falls tests don't predict a fall on their own
The CDC uses the chair stand, the timed up and go and a 4-stage balance test to pick out older adults for a fuller falls check. On their own these tests predict falls poorly, and NICE advises against using them to predict a person's risk. If you've fallen or feel unsteady, ask your GP about a falls assessment whatever your score.
Sources 1, 19, 20, 21, 22
Check first, and have someone with you
Answer the PAR-Q+ (Physical Activity Readiness Questionnaire) before a hard test such as push-ups to fatigue, and check with your GP first if you have a heart condition, chest pain, dizziness or fainting. Have someone beside you for the chair, walking and balance tests, as the CDC's forms advise, and for the floor test, especially if you've fallen in the past year or feel unsteady.
Sources 23, 24, 1, 19, 20