Resistance exercise is the most effective form for muscle gain. Research suggests that it should be performed with a range of 10–20 sets per muscle group per week,[1][2] although some people may experience substantial muscle gain performing a lower number of sets per week. Each muscle group should be trained at least once per week.[3] When performing more than 10 sets per week for a given muscle group, it may be beneficial to divide the sets over several days (e.g., 6 sets/day on 2 days, rather than 12 sets on one day).[4]
Each set should be performed to, or close to, muscular failure (i.e., the point at which another concentric repetition cannot be performed with proper form),[5] using a load equivalent to approximately a 5- to 30-repetition maximum.[6] Machine and/or free weight exercises may be used, as they are equally effective.[7] A rest interval of about 60–180 seconds should separate each set, with the upper end of this range generally reserved for multi-joint exercises (e.g., squats).[4]