Your upper hamstrings assist the glutes in extending the hips. Your lower hamstrings flex the knees. The sliding or rolling leg curl works both functions with minimal spinal stress making it the best hamstrings exercise for longevity.
Follow this 5-step progression for best results:
Full Range Reps
Add Weight or Band Tension
Single-Legged Full Range Reps
No sliders? Modify with the glute-ham walkout. But you can also use socks or paper plates on a wooden or tile floor and furniture sliders on carpet or turf.
This exercise never gets easier. In fact, it only gets harder with practice as you improve form, increase range of motion & get a better mind-muscle connection. The key is to fight to keep your hips fully extended throughout the drill. Drive your arms underground to maximize leverage and stability plus strengthen your upper back.