The very first exercise that should get the boot from your workout protocol is those inner and outer thigh machines.
Sure, you feel the burn.
But what exactly does that burn represent? All that burn is will be lactic acid building up in the muscle tissue. And while there may be slight benefits to this, it doesn’t really indicate you’re working hard.
If you lifted a two pound weight for enough reps, you’d also feel the burn but this clearly is not getting you any strength building results.
If you want to firm up the thighs and bum, do some heavy weight squats or lunges. This will work the muscle tissues far better and actually give your body some shape.