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Your chronological age is the number of years you’ve lived, but that isn’t the greatest predictor of your health. Doctors often consider your biological age to determine your overall health or longevity.

There is no universal formula for determining someone’s biological age. Doctors usually consider one’s family health history, diseases, conditions, sleep, diet, and exercise habits. They can also determine someone’s biological age by checking their balance, grip strength and endurance.

A new study by the Mayo Clinic found that your ability to balance on one foot is an indicator of bone, nerve, and muscle strength and can help determine your biological age.

"Balancing on one leg requires multiple components of physiological function that each typically declines with age, including strength in the leg and postural stabilizing muscles, neuromuscular coordination, and intact sensory information and reflexes," Prof David Proctor, aging and exercise expert at Pennsylvania State University, told BBC Science Focus.

"Attempts to prevent or slow the loss of muscle strength and balance in older age could mean the difference between remaining functionally independent and early admission to a nursing home!" he continued.

The researchers asked people between the ages of 50 and 80 to balance for 30 seconds on each leg with their eyes open and closed. The team found that for every additional 10 years of age, swaying increased by 6.3% if their eyes were open and 10.5% if their eyes were closed.

So, if you are over 50 and can stand on one leg for 30 seconds without significant wavering, you’re probably doing well for your age. But if you experience considerable wavering, then you should work on training your neuromuscular system.

The study comes two years after researchers in Brazil found that older adults who cannot stand on one foot for 10 seconds or more are nearly twice as likely to die in the next 10 years. The inability to stand on one foot shows that the body has lost neuromuscular strength, but it also makes one vulnerable to falling.

“Remember that we regularly need to stay in a one-legged posture, to move out of a car, to climb or descend a step or stair and so on," the study’s author, Dr. Claudio Gil Soares de Araújo, a sports and exercise physician and director of research and education at the Exercise Medicine Clinic-CLINIMEX in Rio de Janeiro, said according to NBC News. “Aged people falling are at very high risk of major fractures and other related complications," Araújo wrote. "This may play a role in the higher risk of mortality.”

The same researchers found a similar test that predicted one’s risk of death. Araújo and his colleagues released a study in 2016 that found that one’ ability to sit on the floor and then stand up without using their knees or handles for support was a good indicator of longevity.

You begin the test with a score of 10 and subtract points on your way up and down for doing the following:

Hand used for support: -1 point

Knee used for support: -1 point

Forearm used for support: -1 point

One hand on knee or thigh: -1 point

Side of leg used for support: -1 point

Those who score in the lowest range, 0 to 3, had up to a 6 times greater chance of dying than those in the highest scores (8 to 10). About 40% of those in the 0 to 3 range died within 11 years of the study.

If you are having trouble with any of these exercises, you can improve by training your neuromuscular system through swimming, running, or cycling. Training programs are also available to help increase neuromuscular fitness. As with any exercise program, please consult a physician before attempting rigorous exercise.