Weight training is a technique for developing muscular strength and endurance by way of progressively lifting increasing amounts of weight. Weight training in itself is not considered a sport. Rather, it is typically used as a form of exercise or training. Weight training is a component of bodybuilding and weightlifting (both of which can also refer to scored events that have spectators).
Repetitions (or "reps") are how many times you work a muscle with an exercise without a break. They are generally grouped into sets, which are separated by short breaks.
Weight training regimens should allow for a rest the day after working a specific muscle group. This allows the healing and recovery time for the muscles to repair and grow. Muscle growth has peaked after 36 to 48 hours, and thus those training for muscle growth should train again at this point. The central nervous system can take up to a week to fully recover; it is most taxed by training to failure, which is when no more repetitions can be completed in the set. Improving the central nervous system's ability to recruit muscle fiber contraction is the most important feature of strength training. These factors affect the training regimes of the different types of athletes. For instance bodybuilders often work in the 8-12 repition range whereas weightlifters and powerlifters more commonly perform more sets but of 1-5 repititions.
Isotonic exercises include pushing or pulling exercises against a movable object. Equipment typically used includes dumbbells, barbells, curl bars and benches. Anything you can pick up can be used for weightlifting, but for best effect it should be pre-measured.
Isometric exercises involve exercises where no 'movement' takes place. An example of an isometric exercise would be to place the palms of your hands against each other and push.
Eccentric contractions involve lengthening of the muscle, and concentric contractions invovle shortening of the muscle. A concentric contraction plus a eccentric contraction make up a single repetition.
Effective weight training makes use of progressive overload: you lift a little more each time you train, and eventually you're able to lift lots more weight than you were able to lift when you started. If one reaches a plateau, then restarting with a lighter weight can allow one to continue using progressive overload. The first example of progressive overload training in literature occurs in the legend of Milo of Croton and his calves.
