  Spectral direct numerical simulations of incompressible MHD turbulence at a
resolution of up to $1024^3$ collocation points are presented for a
statistically isotropic system as well as for a setup with an imposed strong
mean magnetic field. The spectra of residual energy,
$E_k^\mathrm{R}=|E_k^\mathrm{M}-E_k^\mathrm{K}|$, and total energy,
$E_k=E^\mathrm{K}_k+E^\mathrm{M}_k$, are observed to scale self-similarly in
the inertial range as $E_k^\mathrm{R}\sim k^{-7/3}$, $E_k\sim k^{-5/3}$
(isotropic case) and $E^\mathrm{R}_{k_\perp}\sim k_\perp^{-2}$,
$E_{k_\perp}\sim k_\perp^{-3/2}$ (anisotropic case, perpendicular to the mean
field direction). A model of dynamic equilibrium between kinetic and magnetic
energy, based on the corresponding evolution equations of the eddy-damped
quasi-normal Markovian (EDQNM) closure approximation, explains the findings.
The assumed interplay of turbulent dynamo and Alfv\'en effect yields
$E_k^\mathrm{R}\sim k E^2_k$ which is confirmed by the simulations.
