Lower Back Fatigue

I was at the range yesterday hitting a bucket. However after around half bucket, my lower back seems to feel tired and fatigued. The only way I could swing was to set up with a more hunched lower back. Is this a problem with the set up or is this normal occurance?

Age, condition, technique, time of day, rain in forecast, etc all play a part in muscle, ligament and tendon 'fatigue'.  You can improve your technique through knowledge and skill. Can improve condition through strengthening and lengthening exercises.  Age, rain and time are outside your control.

How much of a warm-up did you do? How often do you hit a bucket of balls? How many balls did you hit and how long did it take you to hit them? How active are you in general outside of golf? How hard were you swinging?

FYI, I have this issue too, especially if I am on the range and hitting driver after driver too fast.  I stick my butt out too much and have an "s" in my spine instead of it being flat.  This is due to many factors including poor conditioning and my continuing to improve my set up.  Read the thread that was provided earlier.  It's a great read.

Also another thing... when you're hitting your buckets. Take your time between balls. The pros do.

I was having back issues a while back and did some research myself. After going to the chiropractor for about 6 months it wasn't getting any better. I read an article on foam rolling. I then Googled foam rolling + back pain and found these two Youtube videos. I started doing the first of these two and realized that it had nothing to do with my lower back and everything to do with my glutes. If you have had a massage you know that there are stress toxins (knots) that they will work out of your back. Well, I had the same knots but larger in my butt. It hurt like all hell rolling them out, but once I got over the pain it completely relieved me of my back pain. I still use the foam roller once a day most of the time just because I like the stretch that it provides. Anyway, take a look at these videos as it could save you a lot of $$ in the end.