Which exercise is NOT recommended for strengthening the back?

The plank jump is not recommended for strengthening the back because this exercise primarily engages the core muscles, shoulders, and legs rather than specifically targeting the back muscles. While it is a dynamic movement that can improve cardiovascular fitness and overall strength, its focus is not on building back strength.

On the other hand, exercises like the back leg raise, wall slide, and crunch are beneficial for developing various muscle groups in and around the back. The back leg raise directly targets the lower back muscles, while wall slides can help improve postural alignment and strengthen upper back muscles. Crunches engage the abdominal muscles but also contribute to stability, which can indirectly support the back. Therefore, the plank jump does not align with the goal of strengthening the back effectively.