The books Convict Conditioning 1 and 2, by Paul "Coach" Wade, argue that the human body is its own gym, and even lay out training progressions, detailed explanations and diagrams of the exercises, and information on "old school" calisthenics / body weight conditioning for insane strength. I have been working through the progressions personally, and teaching from the books to students in my boxing, MMA, and karate classes. I can say that the progressions are the real deal. The body was built to run, jump, climb, push, and pull - all of these being survival skills. Convict Conditioning teaches these in its training progressions. Essentially, body weight conditioning is the way to go for optimal athletic performance. From easy wall pushups to one armed pushups, remedial pull ups, basic ab work to hanging leg raises, and many other types of exercises. All in all, I would argue that a lot of these exercises are similar to what is taught in many martial arts and karate classes, especially the pushups, squats, and leg raises.
The author also argues against what he calls the modern fitness scam. We're put on a variety of weight machines that isolate muscles, or work out on a bench and told to work out to pressing or curling genuinely heavy amounts of weight, or lifting very light free weights for lots of reps. Sure, we do see some results, and there's no doubting the serious strength exhibited by the world's best bench pressers. Although, on the other hand, the body was not meant to handle those kinds of loads - the joints and tendons don't naturally cope with them. Also, machines, heavy benching, and light free weights do very little for overall health or overall functional strength, especially compared to body weight conditioning.
Prison inmates won't always have access to any kind of equipment. Hence, the name Convict Conditioning - the author's training progressions lay out a lot of things that prisoners practice when in lockdown. The argument is not that the prison lifestyle is something to be sought after, but that the human body is its own gym. All you need, at most, are a wall, something to hang from, a chair, a tennis ball, and a medicine ball or basketball.
Convict Conditioning also contains history about exercise and old school strongmen, as well as details on warming up, supplementary exercises, workout routines from beginner to very advanced, and more. The second book goes beyond the basics, and includes such things as training progressions for the neck, forearms, and calves, and how to train your joints.
The full body, functional strength training that Paul Wade lays out is very beneficial to athletic performance in general, and certainly for martial arts. I especially recommend his books to everyone enrolled in self defense, Kungfu, Taekwondo, and Karate classes, or similar styles.
To view a video playlist of the book and info on where to find the book, view our Convict Conditioning book page.