Add that with possibility of healing minor injuries through healing magic or alchemy and you could make an effective training in a fantasy world.
You might want too read Kaifuku Jutsushi no Yarinaoshi, the healing system took a drastic power up and change there
If you were hoping to build your muscles back up after a work out, you'd need to have it accelerate the bodies natural healing capabilities. If you were doing restoration type healing, the muscle fibers would be restored to the state they were before being broken down, thus leaving you with no gains after exercising. This would also be able to heal minor injuries such as cuts and if properly treated, bone fractures. Scars would remain however, and weakness would potentially remain if not treated properly.
Conjuration magic, the ability to summon and infuse energy into a creature or object. White necromancy, boosting life force in creature.
Nope like in a world where you can use magic to make doing that possible, there's a lot of magic system that you could do or cannot depending on the authors world.
...dual cultivation Chiyu Mahou no Machigatta Tsukaikata ~Senjou wo Kakeru Kaifuku Youin~ in this novel, the healers are training like an army too. They didn't exactly explain what kind of healing system is it, but some of the healers are now physically stronger than some army
just go and get a jade meteor rock from some weathered down Chinese shop. That is all you need. (source: CD)
I don't remember the name of the novel but if i remember correctly, the MC was using electricity (lightning element) on his muscles while being stationary which overtaxed it or some shit. After being broken and repaired over and over he got stronger.
Break apart, reconstruct, and deconstruct said reconstructions to newly fused constructions, then combined to forge new construct that synergies with accompanying constructs. Repeat process until limit is bypass or achieved.