the closest sport to osu! i can think of in terms of how it can stress your forearm and the muscles/tendons on both sides of your hands and forearms is arm wrestling and Devon Larratt who you can think of as the Cookiezi of that suggests very light training instead of rest for building up strength and stamina AND recovering in a timely manner at the same time, so that is why I suggest this as well.
Vuelo Eluko wrote:it is normal, and no need to stop playing entirely, light playing i.e non stamina/stream intensive maps that you can tap while your arm is relaxed will actually help. Rest is overrated, keep it moving, keep the blood pumping. More blood flow is conducive to healing and strengthening. Just don't hurt yourself more and you're golden.I would say it's better to take at least 1 day a week off for recovery. It's the same as when you play sports or go to the gym, you need to let your body rest.
It makes a lot of sense as well, we are talking about osu!, not a sport such as football, nor full body weight lifting, it's not just your muscles being stressed in those but you can overwork your nervous system, back, and various other parts of your body from the lymphatic system to your heart by not taking time off at all. You can just ruin yourself. With osu! when it comes to intensive tapping or aiming you only really have to be concerned with everything at and below the elbow up to the fingertips, and keeping those parts moving will increase blood flow which has obvious benefits when you are recovering and trying to build up your stamina.
Very light play after training stamina to the point you are sore should be fine, just maps that don't cause you to tense your arm or hand at all and allow you to tap gently; particularly if you use a good heavy switch like blacks to de-load your extensors even more. Just make sure you are getting good amounts of sleep and are eating properly.
Personally, I would just play jump maps within my finger movement only singletappable bpm in the meantime instead of resting, as well as low bpm stream maps too but some people have to tense up in order to acc those for some reason (I don't understand it personally, sometimes i dont even bottom out during low bpm streams) so that's going to be by a case by case basis.
You could also practice not bottoming out to go even easier. Tap like a butterfly, recover like a champ.