The 'devil training' period that the new reserved warriors of every year had to spend in the First Reserved Camp took a whole month. According to the general instructor of the new recruits, Instructor Thuja, "It's a process where the normal transform into marvels. It might seem or sound unbelievable, but the logic behind the whole process is simple: to destroy and rebuild."
Indeed, the logic was to destroy and rebuild.
Compared to the old civilization, when a scrawny man wanted to become a macho hunk, he would need to undergo power training.
Extreme recovery could repair torn muscles during training. Combined with a great amount of protein replenishment, the muscles would be mended faster and be stronger than before. Using this concept as a base, evolved muscles would gradually form.
It might sound like an easy task, but when Tang Ling and the other reserved warriors experienced the training, it was hellish torture.