Top speed, full send. Nothing builds power like it.
Warm up fully first. Cold sprints are how hamstrings get pulled.
Sprinting is close to a full-body power exercise dressed up as cardio, demanding maximum output from your legs, hips and arms for a few explosive seconds at a time. Near-max efforts train top-end speed and fast conditioning in a way steady running never touches. A little goes a long way, which is why short sprint sessions fit neatly around lifting.
Start with 4 to 6 efforts of 10 to 20 seconds with a full walk-back recovery between them. Quality beats quantity, once your speed visibly drops, the session is done.
Because you are asking your hamstrings for near-maximum output. Jogging plus a few build-up runs at increasing speed prepares the tissue, going straight to full speed cold is the classic way to pull something.
They do a different job. Sprints build speed and power in minutes, steady cardio builds your aerobic base, and most people benefit from keeping both in the week.
