IFT can be used fr various purposes but 2 main criteria r 1)pain relief
2)muscle strengthening(basically to maintain contractility of ms along wd pt. effort
higher d frequency lower d resistance hence lower intensity required.you r correct in saying that but if ur aim is to get better ms contraction & u want pt to contract along wd that the choose base frequency of 2Khz.:hat
other options r
1)faradic
2)russian-requires long sessions to be able to show sm hypertrophy