mooreadam: Sorry, this is probably a dumb question but do you want me to test the vs pins with a multimeter or through arduino? I ran this sketch to test the voltage but not sure if thats what you meant...
I meant with a multimeter. You need to make sure both batteries have juice and are pretty close in voltage to one another.
mooreadam: But when put on the muscle sensors every turns to 0.
I'm a little unclear what you mean here. Do you mean when you put on the electrodes? Are you still not seeing a response when you flex?