The 30-second sit-to-stand test is a scientific standard for assessing longevity—here are the benchmarks to aim for in your 60s, 70s, 80s and 90s

How many times could you stand up from a chair and sit down again, without using your hands, in 30 seconds? The answer may indicate your ability to maintain independence in later life.

The 30-second sit-to-stand test, as it’s known, first…