Sixty-four healthy male participants ( mean SD age , 24.2 3.3 years ; height , 181.8 26.1 cm ; mass , 82.4 11.8 kg ; subcutaneous fat thickness , 0.61 0.19 cm ) were randomly assigned into 1 of 6 groups : ( 1 ) 1-mA current , 1-mm probe depth ; ( 2 ) 1-mA current , 4-mm probe depth ; ( 3 ) 2-mA current , 1-mm probe depth ; ( 4 ) 2-mA current , 4-mm probe depth ; ( 5 ) in vivo retrodialysis ; and ( 6 ) skin perfusion flowmetry .