The concept of progressive overload in fitness training involves gradually increasing the demands placed on the body to stimulate muscle growth, improve fitness, and enhance performance. This can be achieved by increasing the weights lifted, altering the number of repetitions, or adjusting workout intensity. By consistently challenging the body, individuals can avoid plateaus and continue making progress toward their fitness goals. However, it is essential to implement gradual changes and allow ample recovery time to reduce the risk of injury and promote long-term success.