  Based on the covariant hamiltonian formalism, we study the dynamics of
spinning test bodies in the Kerr and Schwarzschild spacetimes. For the first
time, we derive the exact solution of circular orbits in the Kerr plane without
truncating the spin of the particle or black hole. A large class of noncircular
bound orbits has been developed by using the world line perturbation theory. It
is found that the spinning body possesses a double frequency, and thus, in
addition to the angular shift, the periastron varies radially proportional to
the alignment and magnitude of spins. By using the method of stability
analysis, we predict the radius of the innermost stable circular orbit (ISCO)
as a function of particle and black hole spin. Furthermore, extending the
perturbative technique for generic orientation of spin in Schwarzschild
spacetime leads to the development of nonplanar bound orbits and the prediction
of fully relativistic precessional frequency of the orbital plane.
