What element is essential during the main workout phase?

High-intensity exercises are fundamental during the main workout phase because this segment is designed to elevate the participants' heart rates and engage their muscles in a way that promotes cardiovascular health, strength, endurance, and overall fitness improvement. The primary goal of this phase is to maximize physical output, allowing participants to effectively burn calories and enhance their fitness levels.

In contrast, group discussions, stretching sequences, and motivational speeches serve different purposes within a fitness class. While group discussions can foster connection and community, they typically occur prior to or after the main workout to set the tone or reflect on the session's progress. Stretching sequences are usually reserved for the warm-up or cool-down phases of a workout. They aim to prepare the body for exercise and to facilitate recovery afterward, rather than being the core focus of the main workout effort. Motivational speeches might boost morale and enthusiasm, but they are not a physical component of the workout session itself. Thus, high-intensity exercises stand out as the crucial element during the main workout phase.