Intramuscular TRT is more effective than transdermal formulations at increasing LBM and improving muscle strength  in middle-aged and older men , particularly in the lower extremities
BACKGROUND Inconsistent fat-free mass ( FFM ) and muscle strength responses have been reported in r and omized clinical trials ( RCTs ) administering  testosterone replacement therapy ( TRT ) to middle-aged and older men .
Our objective was to conduct a meta- analysis to determine whether TRT improves FFM and muscle strength in middle-aged and older men and whether the muscular responses vary by TRT administration route .
Effects of transdermal testosterone on bone and muscle in older men with low bioavailable testosterone levels, low bone mass, and physical frailty.
OBJECTIVES To investigate the effects of testosterone supplementation on bone , body composition , muscle , physical function , and safety in older men . DESIGN Double-blind , r and omized , placebo-controlled trial . SETTING A major medical institution . PARTICIPANTS One hundred thirty-one men ( mean age 77.1 + /- 7.6 ) with low testosterone , history of fracture , or bone mineral density ( BMD ) T-score less than -2.0 and frailty . INTERVENTION Participants received 5 mg/d of testosterone or placebo for 12 to 24 months ; all received calcium ( 1500 mg/d diet and supplement ) and cholecalciferol ( 1,000 IU/d ) . MEASUREMENTS BMD of hip , lumbar spine , and mid-radius ; body composition ; sex hormones , calcium-regulating hormones ; bone turnover markers ; strength ; physical performance ; and safety parameters . RESULTS Ninety-nine men ( 75.6 % ) completed 12 months , and 62 ( 47.3 % ) completed end therapy ( mean 23 months ; range 16 - 24 months for 62 who completed therapy ) . Study adherence was 54 % , with 40 % of subjects maintaining 70 % or greater adherence . Testosterone and bioavailable testosterone levels at 12 months were 583 ng/dL and 157 ng/dL , respectively , in the treatment group . BMD on testosterone  increased 1.4 % at the femoral neck and 3.2 % at the lumbar spine ( P=.005 ) and decreased 1.3 % at the mid-radius ( P<.001 ) . There was an increase in lean mass and a decrease in fat mass in the testosterone group but no differences in strength or physical performance . There were no differences in safety parameters . CONCLUSION Older , frail men receiving  testosterone replacement increased testosterone levels and had favorable changes in body composition , modest changes in axial BMD , and no substantial changes in physical function
Intramuscular TRT is more effective than transdermal formulations at increasing LBM and improving muscle strength  in middle-aged and older men , particularly in the lower extremities
BACKGROUND Inconsistent fat-free mass ( FFM ) and muscle strength responses have been reported in r and omized clinical trials ( RCTs ) administering  testosterone replacement therapy ( TRT ) to middle-aged and older men .
Our objective was to conduct a meta- analysis to determine whether TRT improves FFM and muscle strength in middle-aged and older men and whether the muscular responses vary by TRT administration route .