(1) where EP/t is the slope of the straight line that fits the protein-bound phenylalanine enrichment across two sequential biopsies, t is the time interval encompassing the two biopsies, EM(1), and EM(2) are the phenylalanine enrichments (tracer/tracee) in the free muscle pool in the two biopsies. The results are presented as %.h-1. Myofibrillar protein synthesis and breakdown will be calculated using the pulse-bolus method.