  Strong decay probabilities are calculated using the Lorentz contracted wave
functions of decay products, determined in the arbitrary dynamical scheme with
the instantaneous interaction. It is shown that the decay width obtains an
additional factor defined by the contraction coefficient $C_m(s)$, which for
two-body equal mass decays is $C^2_m(s)= 4m^2/s$ , $s= E^2$. The resulting
decay widths are compared to the experimental data, where in particular the
$\rho(770),\rho(1450) $ decay data require an additional $1/s$ dependence of
the width to fit the data. Important consequences for the dynamics of hadron
decays and scattering are shortly discussed.
