How to get raw emg signal without offset
You need something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

That adds 2.5V to the AC signal.  It also inverts the AC, but I don't think that will bother things.

Depending on how you have your existing TL072 connected, you could probably do this all in that one stage.

But, you didn't post your schematic and I don't feel like drawing one from your breadboard sketch, so I'll just leave this as is.



You've got 5V on the Arduino, but it is usually very noisy.  I've used 5V in the schematic just to make it clear that you need a regulated voltage.  The two 9V batteries aren't regulated, so you can't generate your 2.5V from them.

You might be able to use the Arduino 5V if you use a large enough value for C1 to clean up all the noise.  I've put a 1µF in.  That ought to do as a starting place.