These tissues are degraded in an orderly fashion, and release mainly alanine and glutamine into the blood.
Fortified with peptide bonded glutamine, which is essentially a third protein source.
One way to do that is to take glutamine.
Supplementing with glutamine spares free glutamine in muscle tissue, counteracts the fall in muscle protein synthesis, and improves nitrogen balance.
What this means is, the very rigors of weight training leak nitrogen carrying glutamine from muscle tissue.