Interrelationships of serum testosterone and free testosterone index with FFM and strength in aging men

Tracey Ann Roy, Marc R. Blackman, S. Mitchell Harman, Jordan D. Tobin, Matthew Schrager, E. Jeffery Metter

Research output: Contribution to journalArticlepeer-review

144 Scopus citations


Muscle mass and strength losses during aging may be associated with declining levels of serum testosterone (T) in men. Few studies have shown a direct relationship between T and muscle mass and strength. Subjects were 262 men, aged 24-90 yr, from the Baltimore Longitudinal Study of Aging, who had T and sex hormone-binding globulin sex hormone-binding globulin (SHBG) measurements, from which the free T index (FTI) was calculated (T/SHBG) from serum samples collected longitudinally since 1963, total body fat mass and arm and leg fat-free mass (FFM) by dual-energy X-ray absorptiometry and arm and leg strength by dynanomometry. Mixed-effects models estimated T and FTI at the time of mass and strength measurements. Age, total body fat, arm and leg FFM, T, and FTI were significantly associated with concentric and eccentric strength. FTI, not T, was modestly, but directly, related to arm and leg strength after fat, arm and leg FFM, height, and age were accounted for and indirectly through body mass. FTI is a better predictor of arm and leg strength than T in aging men.

Original languageEnglish (US)
Pages (from-to)E284-E294
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number2 46-2
StatePublished - 2002
Externally publishedYes


  • Aging
  • Skeletal muscle mass

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)


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