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 .
Dual-energy X-ray absorptiometry lean soft tissue hydration: independent contributions of intra- and extracellular water.
Dual-energy X-ray absorptiometry ( DEXA ) provides a measure of lean soft tissue ( LST ) . LST hydration , often assumed to be constant , is relevant to several aspects of DEXA body composition estimates . The aims of this study were to develop a theoretical model of LST total body water ( TBW ) content and to examine hydration effects with empirically derived model coefficients and then to experimentally test the model 's prediction that , in healthy adults , LST hydration is not constant but varies as a function of extra- and intracellular water distribution ( E/I ) . The initial phase involved TBW/LST model development and application with empirically derived model coefficients . Model predictions were then tested in a cross-sectional study of 215 healthy adults .  LST was measured by DEXA , extracellular water ( ECW ) by NaBr dilution , intracellular water ( ICW ) by whole body (40)K counting , and TBW by (2)H(2)O dilution .  TBW estimates , calculated as ECW + ICW , were highly correlated with ( r = 0.97 , SEE = 2.1 kg , P < 0.001 ) and showed no significant bias compared with TBW measured by (2)H(2)O. Model-predicted TBW/LST was almost identical to experimentally derived values ( means + /- SD ) in the total group ( 0.767 vs. 0.764 + /- 0.028 ) . LST hydration was significantly correlated with E/I ( total group , r = 0.30 , SEE = 0.027 , P < 0.001 ) . Although E/I increased with age ( men , r = 0.48 ; women , r = 0.37 ; both P < 0.001 ) , the association between TBW/LST and age was nonsignificant . Hydration of the DEXA-derived LST compartment is thus not constant but varies predictably with ECW and ICW distribution . This observation has implication s for the accuracy of body fat measurements by DEXA and the use of TBW as a means of checking DEXA system calibration
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 .