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 .
Differential anabolic effects of testosterone and amino acid feeding in older men.
The interaction between testosterone and exogenous amino acids was studied in older men before and after 6 months of testosterone administration . Twelve healthy older male subjects were r and omly assigned in double-blind fashion to receive either testosterone enanthate [ T ; n = 7 ; 68 + /- 3 ( + /-SE ) yr ] or placebo ( n = 5 ; 67 + /- 3 yr ) for 6 months . Muscle protein kinetics were determined using stable isotope methodology , arterial-venous difference across leg muscle , and muscle biopsies . In addition , ubiquitin-proteasome activity was measured in muscle biopsies as an indicator of muscle protein breakdown . T improved fasting net protein balance , although it remained significantly negative . The improvement in net balance was due to a decrease in muscle protein breakdown , as protein synthesis was unchanged . Ubiquitin-proteasome activity was also decreased with T. Exogenous amino acids increased protein synthesis in both placebo and T groups , but to a lesser degree after 6 months of T treatment . These results indicate that prolonged T administration increases net protein balance in the fasted state , but no additive effect is demonstrated when combined with amino acid feedings . Taken together , however , these diverse stimulatory effects can increase lean body mass and muscle strength over time
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 .