After block , the quadriceps maximum voluntary isometric contraction increased to 193 % ( 95 % confidence interval [ CI ] , 143-288 ) of the baseline value in the ACB group and decreased to 16 % ( 95 % CI , 3-33 ) in the FNB group with an estimated difference of 178 % ( 95 % CI , 136-226 ) , P < 0.0001 .