Up from Sitting on a Chair with One leg

There is a simple test.  My classmate send a viral video which says we lose about 8% muscle mass a year past certain age.  The only way is to reduce the loss by being active.  If you cannot perform this test, high chance of disability or immobility by age of 70s.

The test is sitting on a chair and getting up with one leg only.  Your hands must be on the shoulder.  So if you cannot do this, it is time to be more active to slow down the loss of your muscle mass.