What would be the most appropriate progression from bodyweight box step-ups?

Holding dumbbells at the side represents an appropriate progression from bodyweight box step-ups as it effectively increases the resistance and load during the exercise, allowing for enhanced strength development. By adding dumbbells, the exercise becomes more challenging without compromising the fundamental movement pattern of the step-up, which can help further develop the lower body muscles, improve balance, and maintain good form.

Additionally, using dumbbells allows for a natural range of motion and can be easily adjusted to accommodate different fitness levels by changing the weight used. This progression is advantageous as it builds on the existing strength and stability developed through bodyweight step-ups while still emphasizing control and technique.