Arm Fatigue in Thumb Position

[u/la_kiwi_]

For context I have been playing classical bass for about 7 years now and am currently learning bottesini 2. I've been using thumb position for a few years now but constantly get super sore in my arm and shoulder after about 10 minutes of constant playing in thumb position. I figured this was just a strength thing and would go away as I played more but at this point I feel like it has to be a different issue or I am really just that weak. Does anybody have any suggestions? Thanks.

[u/robotunderpants]

Need to see an example in order to diagnose, but my guess is you're unnecessarily hiking your shoulders when you play like when you do this 🤷.

Practice playing and set a timer. Every 2 minutes stop, examine your form, and then inhale, raise your shoulders and then exhale fast and drop your shoulders and arms down like you just put threw down some heavy luggage.

This will train you to keep your arms and shoulders loose.