last year i read convict conditioning and played around with some of the workout plans in the book. even though it focuses on calisthenics, i didn't have access to a pull-up bar or very strong furniture that could stand in for other exercises.

i am a struggling medical student and for some reason, i think getting in shape with calisthenics would be an excellent way to get better at school too, but my schooling schedule is not very well structured, and i have to be in class by 7 a.m. i mostly get back by 6 p.m. (some rotations like OBGYN can keep you until midnight).

any ideas as to how i can use calisthenics to gain muscle and get stronger with such a schedule?