Each star orbits the center of our Galaxy, and its speed and position depend on its history of interactions with dust and other stars in the Galactic plane. As stars age, they have more and more kinematic interactions, which overall increase the total stellar velocity and result in older stars spending more time further from the plane of the Galaxy. Because the changes in orbital motion are a stochastic process, kinematics is only a reliable age indicator when considering populations or groups of stars.
I mainly use kinematics to examine the usefulness of other age indicators. As part of my dissertation, I looked at the J-K colors of L dwarfs compared to kinematics, finding that older stars have bluer J-K colors than younger stars, presumably due to the effects of lower metallicity in older stars or thicker clouds in younger stars.
I am currently working with my BOSS Ultracool Dwarfs sample of 13000 late-M and L dwarfs with spectra from SDSS and Galactic kinematics to examine other properties related to age. Initial results suggest that several colors are related to age, and that magnetic activity and age are related even at these late spectral types where spin-down is less efficient.
The Effect of Atmospheric Cooling on Vertical Velocity Dispersion and Density Distribution of Brown DwarfsApJ 2017
The Brown Dwarf Kinematics Project (BDKP). IV. Radial Velocities of 85 Late-M and L Dwarfs with MagEApJs 2015
Colors and Kinematics of L Dwarfs from the Sloan Digital Sky SurveyAJ 2010