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 Testosterone Supplementation for 3 Years on Muscle Performance and Physical Function in Older Men
Context : Findings of studies of testosterone ’s effects on muscle strength and physical function  in older men have been inconsistent ; its effects on muscle power and fatigability have not been studied . Objective : To determine the effects of testosterone administration for 3 years in older men on  muscle strength , power , fatigability , and physical function . Design , Setting , and Participants : This was a double-blind , placebo-controlled , r and omized trial of healthy men ≥60 years old with total testosterone levels of 100 to 400 ng/dL or free testosterone levels < 50 pg/mL. Interventions : R and om assignment to 7.5 g of 1 % testosterone or placebo gel daily for 3 years . Outcome Measures : Loaded and unloaded stair-climbing power , muscle strength , power , and fatigability in leg press and chest press exercises , and lean mass at baseline , 6 , 18 , and 36 months . Results : The groups were similar at baseline . Testosterone administration for 3 years was associated with significantly greater performance in unloaded and loaded stair-climbing power  than placebo ( mean estimated between-group difference , 10.7 W [ 95 % confidence interval ( CI ) , −4.0 to 25.5 ] , P = 0.026 ; and 22.4 W [ 95 % CI , 4.6 to 40.3 ] , P = 0.027 ) , respectively . Changes in chest-press strength ( estimated mean difference , 16.3 N ; 95 % CI , 5.5 to 27.1 ; P < 0.001 ) and power ( mean difference 22.5 W ; 95 % CI , 7.5 to 37.5 ; P < 0.001 ) , and leg-press power were significantly greater in men r and omized to testosterone than in those r and omized to  placebo . Lean body mass significantly increased more in the testosterone group . Conclusion : Compared with placebo , testosterone replacement in older men for 3 years was associated with modest but significantly greater improvements in stair-climbing power , muscle mass , and power . Clinical meaningfulness of these treatment effects and their impact on disability in older adults with functional limitations remains to be studied
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 .