What does the principle of progressive overload involve?

The principle of progressive overload is integral to improving physical fitness. It involves gradually increasing the amount of stress placed on the body during exercise to stimulate muscle growth, enhance endurance, and improve overall physical performance. By progressively increasing resistance, duration, intensity, or frequency of workouts, the body is challenged in a way that promotes adaptation and improvement. This method prevents plateaus, reduces the risk of injury, and ensures continuous gains in strength and endurance.

In contrast, decreasing workout intensity or maintaining the same routine indefinitely would limit improvements and possibly lead to stagnation in progress. Additionally, emphasizing speed over resistance does not align with the core concept of progressive overload, which prioritizes the incremental increase of exercise difficulty to enhance physical capabilities. Thus, the correct choice accurately captures the essence of this foundational principle in fitness training.