The present analysis provides an estimate of the average treatment effects of testosterone therapy in middle-aged men .
OBJECTIVES Ageing in men is associated with a gradual decline in serum testosterone levels and a concomitant loss of muscle mass , accumulation of central adiposity , impaired mobility and increased risk of bone fractures .
Whether and rogen treatment might be beneficial in these subjects is still under debate .
We have carried out a systematic review of r and omized controlled trials ( RCTs ) evaluating the effects of testosterone ( T ) administration  to middle-aged and ageing men on body composition , muscle strength , bone density , markers of bone metabolism and serum lipid profile .
Testosterone administration to older men improves muscle function: molecular and physiological mechanisms.
We investigated the effects of 6 mo of near-physiological testosterone administration  to older men on skeletal muscle function and muscle protein metabolism .  Twelve older men ( > or = 60 yr ) with serum total testosterone concentrations < 17 nmol/l ( 480 ng/dl ) were r and omly assigned in double-blind manner to receive either placebo ( n = 5 ) or testosterone enanthate ( TE ; n = 7 ) injections . Weekly intramuscular injections were given for the 1st mo to establish increased blood testosterone concentrations at 1 mo and then changed to biweekly injections until the 6-mo time point . TE doses were adjusted to maintain nadir serum testosterone concentrations between 17 and 28 nmol/l . Lean body mass ( LBM ) , muscle volume , prostate size , and urinary flow were measured at baseline and at 6 mo . Protein expression of and rogen receptor ( AR ) and insulin-like growth factor I , along with muscle strength and muscle protein metabolism , were measured at baseline and at 1 and 6 mo of treatment . Hematological parameters were followed monthly throughout the study . Older men receiving  testosterone increased total and leg LBM , muscle volume , and leg and arm muscle strength after 6 mo . LBM accretion result ed from an increase in muscle protein net balance , due to a decrease in muscle protein breakdown . TE treatment increased expression of AR protein at 1 mo , but expression returned to pre-TE treatment levels by 6 mo . IGF-I protein expression increased at 1 mo and remained increased throughout TE administration . We conclude that physiological and near-physiological increases of testosterone in older men will increase muscle protein anabolism and muscle strength
The present analysis provides an estimate of the average treatment effects of testosterone therapy in middle-aged men .
OBJECTIVES Ageing in men is associated with a gradual decline in serum testosterone levels and a concomitant loss of muscle mass , accumulation of central adiposity , impaired mobility and increased risk of bone fractures .
Whether and rogen treatment might be beneficial in these subjects is still under debate .
We have carried out a systematic review of r and omized controlled trials ( RCTs ) evaluating the effects of testosterone ( T ) administration  to middle-aged and ageing men on body composition , muscle strength , bone density , markers of bone metabolism and serum lipid profile .