Something that goes way overboard or is excessive is immoderate. Immoderate exercise can lead to pulled muscles and sprains.
If someone's behavior is unreasonable or extreme, you can call it immoderate. Immoderate spending results in arms full of shopping bags and a whole lot of credit card debt, and immoderate eating at a huge breakfast buffet can give you a stomach ache for the rest of the day. Immoderate is the opposite of the adjective moderate, which means calm or restrained. Both words have the same Latin root, moderatus, "within bounds, or observing moderation."