Multivariable analysis adjusted for sex, age, baseline block number, bone stiffness, TUG performance, or handgrip strength simultaneously revealed that low handgrip strength (<26 kg in men, <18 kg in women) and low mobility (>13.5 seconds) at baseline were both independently associated with kyphosis progression (adjusted risk ratio [95% confidence interval]: 2.11 [1.06-4.20] and 2.48 [1.26-4.89], respectively).