[en] NMR spin relaxation experiments performed on healthy mouse muscle tissue at 40 MHz and 293 K are reported. The spin-lattice relaxation experiments were performed using different combinations of selective and nonselective radio frequency pulses. Relaxation experiments in the rotating frame at H₁ = 10, 5 and 1 G are also reported. The experimental results were analyzed using the spin-grouping method, which yields the sizes of the resolved magnetization components as well as their T₂'s and T¹'s (or T/sub 1rho/'s) for the nonexponential relaxation functions. These results were analyzed further for the exchange between different spin groups. It has been found that to explain all of these experimental data it was necessary to use a four-compartment model of the muscle tissue that consists of a lipid spin group, a solid-like spin group (mainly proteins), a bulk water spin group and a bound water spin group. The chemical exchange rate between bulk and bound water was found to be 29 +/- 9s^-1 at room temperature. The exchange rate between the bound water and the solid moderator was estimated to be ∼500 s^-1