Changes in muscle mass, muscle strength, and power but not physical function are related to testosterone dose in healthy older men.
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.
Storer
Thomas W
TW
Section of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, Boston, Massachusetts, USA.
Woodhouse
Linda
L
Magliano
Lynne
L
Singh
Atam B
AB
Dzekov
Connie
C
Dzekov
Jeanne
J
Bhasin
Shalender
S
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*
D000728:Androgens; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; C004648:testosterone enanthate; D016729:Leuprolide
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