So I'm slowly working my chops back up after 6 months or so of no practice due to wrist pain. I'm working it slowly, and paying a lot of attention to wrist positions. One thing I've noticed is that it seems to be impossible to keep my left hand straight in all positions. I can comfortably play above the 7th fret with a relaxed open hand technique, and get a good string/fret range, with a straight wrist. However as soon as I bring it down and start trying to play fifths/octaves below the 5th fret (especially the low F on the E string) I either have to sharply curve my wrist, or lose all stretch in my hand position. Is there a solution to this, or just something I have to live with? Is it possible to play with a straight wrist 100% of the time, or is it just not possible? I'm considering restringing one of my basses BEAD just to over come this, but I'd rather overcome it with good technique if possible.
With a strap, I've been going back and forth with my strap length. I used to play it short, got a lot of wrist pain, so I dropped it down a bit. It's not that low... the top horn of my 4003 is about belly button height. I'll play with it back and forth but I find the bend worse low down with a higher strap.
How are you holding the bass? Are you holding it perpendicular to your body? Try holding it more vertical
Same thing happened to me when I got my 19mm 5er. I started using less pressure on the strings and the pain went away and in return helped my playing. So try a little less pressure on the strings, you should be able to get away with a little bend in the wrist and not feel it later.
I usually stick to the lower 7 frets. I keep my bass body centered near my belly button and angle my headstock up. I use a thick padded comfort strapp (tm). As you can see from the image, I have no problem keeping my wrists straight. If you're slavishly trying to maintain a 1 finger per fret technique across those big frets, that could also be forcing you to bend your hand too much. I generally favor 124/Simandl/URB style fingering down there.
Try playing those F's and F#'s on the E with your middle finger instead of index. Makes a world of difference.