A new simple performance test focused on agility in elderly people: The Ten Step Test. 
Not only the reduction of muscle strength or balance, but also the reduction of the agility are regarded as important factors of falls in elderly people.  If an agility test for elderly people is established, the precision of the fall prediction rises and can be used for individual training.  To develop a new performance test focused on agility for elderly people and to evaluate the usefulness of this test.  Cross-sectional study.  The Welfare Center of Kagami Town, Kagami Town Office, etc.,  Kochi, Japan.  828 community-dwelling, independent adults aged 20-99 years with no obvious cognitive or functional disability, were randomly recruited from Kagami town and the surrounding areas.  The Ten Step Test (TST, a new performance test), motor reaction time (MRT), knee extensor isometric strength, single leg standing time (SLST), and some other tests were used to evaluate the criterion-related validity and the content validity.  TST was developed as a modified version of other step tests which require the subjects to place the whole foot on a block, then return it to the floor.  In addition, female participants over 70 were asked whether or not they had fallen in the past year.  Excellent reliability for TST was found for interrelation (intra-class correlation coefficients, ICC = 0.96), and re-test reliability was sufficient (ICC = 0.86).  Evidence for criterion-related validity was found through high single correlation with the timed supine-to-stand (r = 0.68) and high single correlation with MRT (r = 0.59).  In addition, content validity was found through low correlation with knee extensor strength (-0.35) and SLST (-0.36) in 112 women over 70 years of age.  The error rate by TST to predict falls (35.2%) was lower than the error rate by muscle strength (44.4%) and the balance (38.7%).  TST confirmed decline after 50 years of age, and it conformed to a cubic curve.  The findings indicate that TST is a reliable measure of agility, and it can help to predict the risk of falls.  The decline of agility accelerates after 50 years of age.  It shows that the decline of agility differs from the decline of leg muscle strength and balance.