Table 2.

¹³C₆-phe enrichment values in various precursor pools and mixed muscle protein used to calculate muscle protein synthesis rate (FSR)

Parameter	Placebo (n = 8)		100 mg Testosterone (n = 6)		300 mg Testosterone (n = 8)
	Baseline	Day 7	Baseline	Day 7	Baseline	Day 7
Plasma 13C6-phea	7.1 ± 0.9	7.2 ± 0.7	7.0 ± 0.8	7.3 ± 0.8	7.0 ± 0.6	7.2 ± 0.7
Muscle Free pool 13C6-pheb	4.3 ± 0.5	4.5 ± 0.8	4.0 ± 0.4	4.4 ± 0.6	4.4 ± 0.2	4.5 ± 0.7
Mixed muscle protein 13C6-phec	0.0195 ± 0.0050	0.0198 ± 0.0017	0.0184 ± 0.0035	0.0250 ± 0.0091	0.0173 ± 0.0023	0.0233 ± 0.0081
Mixed muscle protein synthesis rate (% per hour)	0.050 ± 0.011	0.052 ± 0.006	0.052 ± 0.010	0.063 ± 0.179	0.044 ± 0.006	0.060 ± 0.026

Mean ± SD. Mixed muscle protein synthesis rate calculated using muscle free pool ¹³C₆-phe enrichment to reflect precursor pool enrichment

^aAverage plasma TTR measured during 11–12 h of the tracer infusion

^bAverage of 3- and 12-h muscle free pool TTR measurements

^cMixed muscle protein TTR increment from 3–12 h of the tracer infusion