Progressive overload is the training principle of gradually increasing the stress placed on your muscles so your body keeps adapting. Without a rising demand, strength and muscle gains eventually plateau because the stimulus no longer exceeds your current fitness level.
You can apply it by raising one variable at a time: more weight, more repetitions or sets, longer sessions, faster work, or shorter rests. Cleveland Clinic sports medicine physician Dominic King, DO, describes it as a tightly controlled way to build muscle mass, strength, and endurance over time.
Progress slowly and keep good form—jumping several variables at once raises injury risk. Source: Cleveland Clinic — Progressive Overload Training.