A few days ago, I started learning Marasy8's arrangement of the "Champion Cynthia" theme from the core Gen IV Pokémon games. I asked a question requesting fingering advice for the first fast (180 bpm) right-hand section, and decided on the following sequence:
5 - 2 - 3 1 - 4 - 1 4 - 5 - 4 3 - 1 - 3 1 - 3 - 1 1 - 2 - 4 3 - 2 - 1
E Bb C# F# Bb C# F# G F# E Bb C# F# Bb F# G A F# E C# Bb
It seemed to have suited me well enough and I was able to start working on getting both hands up to speed. After about 30 minutes worth of repetitions with tempos approaching 170-180 bpm as I progressed, I could feel moderate soreness throughout my fingers which became more significant as the minutes went by; spreading to the metacarpal regions of my inner hand, followed by my wrist and forearm. Allow me to point out here that while there is a very present "burn" from a buildup of lactic acid, this seems to be an independent issue. It was only really noticeable while playing these notes, and didn't affect me when I went onto play other pieces right afterwards.
I found that it subsided after a few seconds of rest and stretches, and was virtually undetectable after a couple of minutes. The pain would, however, return more readily upon resuming from such breaks, making practicing much more onerous than usual. I've made a reasonable effort over the past few days to consolidate my technique and try to reduce tension wherever possible, slightly alleviating the soreness but nowhere near enough for me to continue practicing without some concern.
Are these normal "stress" pains from playing at these speeds for extended periods of time, or is an issue with my fingering or technique more likely to be the culprit? I'd be happy to link a video of my playing in an edit if necessary.