I was bench pressing today and had my back slightly arched. As I did more reps, my lower back started feeling a lot tighter and was very uncomfortable. Do you have any advice on how to fix this?
This is normal on your top sets, it should not be a big deal on your earlier sets.
You can try squeezing your butt together, maybe that eleviates some off the discomfort. If it's realy painfull seek medical help.
OK yeah it only bothered me when it got really heavy.
I had similar issues a while back, mainly because I would bench on Wed after squats & good mornings on Mon. Maintaining a really tight arch was quite painful so I just went a bit flatter & even threw a one board at times, alternatively I rotated my Mon session so I was fresher back wise on bench day!
Best advice don't aggravate it just to get a few good training sets in!