When it comes to building muscles there are two basic ways to do that. One will create strong but lean muscles and the other will induce bulked up effect, but toning is important in both cases. Also, muscles can be built with or without the use of additional weight. Building muscles without weights can produce almost the same effect as with using additional weight, at least up to a certain point, from which further mass growth will require additional weights.
Training session without the use of additional weight will not be any less effective than with weights. Of course, there are some exercises that should be applied and one of the most important is push up. This is universal exercise and it will increase the strength of complete arms, including biceps. Push-up is performed when the body is parallel with the floor, propped on palms and feet. Actually, there are several forms of push-ups and each is focusing different muscles. For example, when there is no distance between the palms on the floor, the triceps is maximally focused. When that distance is wide, the shoulders are more focused. In both of these forms, the biceps muscle is also developing. When a standard form becomes a bit easy, there are some things that can be done in order to increase the resistance effect. Level of feet should be raised, which can be done easily, with the help of the chair. This changed position will put more weight into push-ups, which is wanted from the start. There are also specific forms that can be performed; for example, instead of palms, fists can be used. Even more extreme variant would be using tips of the fingers (three fingers, not five!). These specific forms are used in martial arts, for strengthening the fingers and joints (judo, aikido, wrestling etc).
Other forms of push-ups include clap push-ups, which is basically the same form but with a twist. When the body is lifted up, hand clap is done. Of course, it has to be done very fast, which additionally strengthens the muscles. There are also one hand push-ups and also inverse stand position push-ups.
Push-up is just one of many forms that can be performed. There are also exercises for abdominal regions, sit-ups, leg raising, crunches, exercises for legs and back. Obviously, an intensive training session can be made only with using the body of the practitioner, and no additional weight.