The Straight Leg Deadlift primarily targets the hamstring whilst also working the glutes, calves and core.
The Straight Leg Deadlift is performed by placing your feet hip width apart with toes pointing forwards. Then reach down to the bar with a slight bend in the knees and arms shoulder width apart. Once set up, you can powerfully stand up pushing your shoulders back and looking ahead, trying to pivot through the hips. Lower the bar back down as low as is comfortable without straining your back and then repeat the movement.
When setting up ensure not to bend your knees too far. This exercise should have minimal movement from the knees and you should feel a slight hamstring stretch at set up.
If you find it is very difficult to reach the floor with the bar, you may need to bend your knees a little more on set up, but it is not necessary to put the bar back on the floor between each repetition- just go as low as is comfortable.
Alternatively, if you find it very easy to reach the floor with the bar, you can raise the level which you are standing on by placing a few plates beneath your feet. This will ensure you still work through your full range of motion.