Two simple strength tests could predict how long you have left to live, a study suggests.Researchers in New York tracked 5,400 women aged 63 to 99 years old for nearly a decade, during which about a third, or 1,900 participants, died.At the start of the study, each woman completed two basic strength tests: A grip strength test, measuring hand grip, and a chair stand test, which measures how quickly someone can sit and rise in a chair five times unaided. Overall, researchers found that those with the strongest grip strength had a 33 percent lower risk of death compared to those with the weakest. For chair stand times, those who could do the test fastest had a 37 percent lower risk of death than those who completed it the slowest.Researchers said stronger muscles could boost longevity because they help someone to stay active and keep moving independently.They also help someone to catch themselves before a fall, which is the leading cause of injury-related deaths for those aged 65 years and older.'If you don't have enough muscle strength to get up, it is going to be hard to do aerobic activities, such as walking,' said Michael LaMonte, an epidemiologist at State University of New York, who led the study. Scientists in New York found that people with stronger grip strength were likely to live for longer than their weaker counterparts