I used to split all my wood by hand, but several years ago, after splitting about 15 cord in a season, I got tendonitis in my elbows so badly that I had great difficulty starting saws. I often had to start them left handed, etc.
So I purchased a hydro splitter which is now 5 years old and splits about 20 cord a year. Giving my arms a rest, followed by some exercises (including hand movement exercises) to help them recover worked for me.
IMO, any repetitive movement can give you problems., even if it does not seem difficult.
Years earlier I had a less serious problem during tax season from putting my computer bag in and out of the back seat of my Mustang, sometimes more than a dozen times a day. The bag is not that heavy, but includes my 17" screen computer, a large tax book and some other items. The problem is the repetitive movement involved reaching and twisting my arm (unnaturally) to get the computer to flop right in the back seat.
I had to slow down and simplify the motion that was giving me some minor chronic pain. I now always put my other hand on the roof of my car to take stress off of my body.
Common sense, and listening to your body, is always the best advice. If you do enough stuff, sooner or later something will bother you.