Strong coupling limit in quantum chromodynamics and the symplectic symmetry of quark bound states

The symplectic group $Sp(2N_fN_c)$ is suggested as the internal group symmetry of quark bound states. $N_f$ is the number of quark flavours and $N_c$ is the number of color degrees of freedom of quark. The effective Lagrangian of quark bound states in the quark-gluon system is constructed in the infinite coupling limit. Some of consequences of the symmetry $Sp(2N_fN_c)$ are considered in the case $N_f=3$.