This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
趞 combines 走 (run) with 昔 (old times). The exact historical development is uncertain, but it likely originally expressed a meaning related to movement or walking in a particular manner.
The running enclosure 走 suggests motion, while the inner 昔 (old times) might hint at an old way of moving. Without a clear meaning, picture an ancient, forgotten way of walking.
For シャク, imagine an old-time runner shakily moving along: shaky -> シャク, and the old 昔 inside 走 wobbles as it runs.