It is hard to imagine that the hamstring stretch is not an essential part of every athlete or sports person's workout program. The hamstring stretch not only helps to protect this vulnerable area, it also contributes to low back health.
One reason that the hamstring stretch is so important is that this area is tight in so many people - can you touch your toes comfortably? Most people can't, yet yogis reckon that if you can't place your palms flat on the floor from a standing hamstring stretch, your flexibility is already compromised.
There are endless variations on this movement, some seated, some standing. Take care with any of these, as the inherent stiffness that most people have means that even pushing a flexibility exercise too far can cause injury.
The standing exercise simply involves bending slowly forward at the waist and reaching downwards. While some people will be able to reach the floor easily, most will only be able to reach part way down the lower legs. Breathe out and relax, allowing your body to sink into the movement for 30 seconds, then slowly straighten back up.
The seated version involves sitting on the floor with both legs out straight. Bend at the waist and reach forward as far as possible while keeping your knees straight. Hold for 30 seconds, relax and repeat.