Plucking hand thumb joint pain when playing thumbstyle?

I play thumbstyle occasionally, with palm muting, to get a different sound on bass to what I usually have. (My bass is very bright and has active EQ, but no tone knob, so if I run it passive, I have to change the sound with my hands.) However, it's something I've been doing recently, and it's not a genuine part of my repertoire.

Sometimes when I do this, I get pain in my main thumb joint (the base, not the knuckle). I don't know if I'm hyperextending my thumb, or whether I need to focus on the technique more to strengthen the thumb over time.

At the end of August, I have to play some reggae songs for a gig, and I would like to be able to play most of the basslines with a muted thumbstyle to better match the vibe. I don't think that'll be a problem for most of the songs, but I don't really have the speed with just my thumb for this song:



I just tried playing it now (I can't do those notes with just thumb downstrokes at that speed, and I don't have the ability to double-thump) and after literally two minutes, I've got thumb joint pain.

Has anyone run into this? Are there any technique issues that can cause this (like hyperextending the thumb or something like that)? Is it just a matter of acclimation? Is it due to trying to palm mute at the same time? Thanks.

 

I'd have to mute at the bridge side, not at the nut side. I do use a fretwrap (or, at least, I have one on my bass, but I don't actually use it unless I'm tapping, which is almost never) but it would only help with open strings. What you say might have merit, though - perhaps it's a positioning issue. I would still have to find a way to mute the strings with my plucking hand, though (it's a six-string bass, so there's a lot of muting to be done) even if I didn't necessarily want to palm mute the notes.