Resistance training is the term for various types of exercises that build strength by relying on the use of resistance to promote muscle growth. The resistance in this type of training can come in many different forms. Bodyweight is the most practical type of resistance and should be learned how to use before trying any other forms. Bands, dumbbells, barbells, and exercise machines can also provide resistance.
There are 3 different ways to contract a muscle against these forms of resistance. Eccentric, concentric, and isometric contractions are all different ways to place stress against the muscle in order to increase its strength and size.