The spine and knees are notorious for copping stretching injuries. This is predominantly due to lack of strength and flexibility in other areas of the body.
Tight hamstrings and weakness in the core muscles can place strain on the muscles of the back, therefore encouraging overstretching of the spinal muscles in effort to carry out a stretch.
The knees can become affected by being ‘locked’ or hyper extended, which can be detrimental to the knee joints, as they are moving in the opposite direction from which they are naturally designated. This adds stress on hamstring tendons and the knee joint itself, whilst also initiating hyper lordosis (sway back) in the lumbar spine. This means that all stretches carried out with locked knees will be performed with misaligned posture, therefore adversely affecting the entire body.
Here is a short circuit you can practice daily to assist in releasing tight or troublesome hamstrings (without straining the low back).