Which of the following exercises is associated with endurance improvement for back extensors?

The exercise known as prone head raises is particularly effective for improving endurance in the back extensors. This exercise targets the muscles along the spine, notably the erector spinae, which are crucial for maintaining proper posture and supporting the back during various activities. By performing prone head raises, individuals can enhance the endurance of these muscles, allowing them to sustain prolonged activities without fatigue.

In contrast, the other exercises listed have different primary focuses. Russian twists primarily engage the core muscles, particularly the obliques, and are less effective for specifically targeting back extensor endurance. The tree pose is a balance and stability exercise that focuses on the lower body and core while also engaging the back muscles to some degree, but it does not isolate the back extensors effectively for endurance. Bicycle crunches predominantly target the abdominal muscles and hip flexors, providing little to no direct advantage for back extensor endurance. Each of these alternatives serves distinct purposes, but prone head raises uniquely position the back extensors for optimal endurance training.