title: Changes in muscle mass, muscle strength, and power but not physical function are related to testosterone dose in healthy older men.
abstract: OBJECTIVE
  To examine the effect of graded doses of testosterone on physical function and muscle performance in healthy, older men.
  
  
  METHODS
  Randomized, double-blind, placebo-controlled clinical trial.
  
  
  METHODS
  General clinical research center.
  
  
  METHODS
  Community-dwelling healthy men aged 60 to 75 (N=44).
  
  
  METHODS
  Monthly treatment with a gonadotropin-releasing hormone agonist plus 25, 50, 125, or 300 mg/wk of intramuscular injections of testosterone enanthate for 20 weeks.
  
  
  METHODS
  Skeletal muscle mass (SMM) was estimated using dual-energy X-ray absorptiometry. Leg press strength was measured by one repetition maximum, leg power by Nottingham Leg Rig, and muscle fatigability by repetitions to failure in the leg press exercise. Stair climbing, 6-meter and 400-meter walking speed, and a timed-up-and-go (TUG) test were used to assess physical function.
  
  
  RESULTS
  Significant testosterone dose- and concentration-dependent increases were observed in SMM (P<.001) and maximal strength (P=.001) but not muscle fatigability. Leg power also increased dose-dependently (P=.048). In contrast, changes in self-selected normal and fast walking speed over 6 or 400 meters, stair climbing power, and time for the TUG were not significantly related to testosterone dose, testosterone concentrations, or changes in muscle strength or power, or SMM.
  
  
  CONCLUSIONS
  Testosterone administration was associated with dose-dependent increases in SMM, leg strength, and power but did not improve muscle fatigability or physical function. The observation that physical function scores did not improve linearly with strength suggests that these high-functioning older men were already in the asymptotic region of the curve describing the relationship between physical function and strength.
authors.affiliation: Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Storer
authors.forename: Linda
authors.initials: L
authors.lastname: Woodhouse
authors.forename: Lynne
authors.initials: L
authors.lastname: Magliano
authors.forename: Atam B
authors.initials: AB
authors.lastname: Singh
authors.forename: Connie
authors.initials: C
authors.lastname: Dzekov
authors.forename: Jeanne
authors.initials: J
authors.lastname: Dzekov
authors.forename: Shalender
authors.initials: S
authors.lastname: Bhasin
mesh_terms: D000368:Aged; D000728:Androgens / Q000008:administration & dosage*; D015992:Body Mass Index; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D006801:Humans; D007866:Leg; D016729:Leuprolide; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000187:drug effects*; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000503:physiopathology; D010807:Physical Endurance / Q000187:drug effects*; D013739:Testosterone / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D000728:Androgens; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; C004648:testosterone enanthate; D016729:Leuprolide
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