Typically the quadriceps win the strength battle and begin to pull the pelvis into a slight anterior rotation or forward tilt (picture a slight arch in the low spine). The hip flexors get in on this action, too, and assist the quadriceps. As the pelvis rotates anteriorly, it raises or elevates the hamstring attachment site, which means the hamstrings get pulled up, and as the pelvis shifts, they become over-lengthened.

Over-lengthening a muscle greatly increases its risk of injury. Along with over-lengthening the hamstrings, pelvic anterior rotation also shortens our back muscles. The typical scenario is tight, shortened quadriceps; tight, shortened hip flexors; tight, shortened back muscles; and tight but over-lengthened hamstring muscles.

1. Stretch and roll your quadriceps and hip flexors regularly. Try this standing quad stretch.
2. Gently stretch your hamstrings:
3. Warm up your spine and perform a cat-cow, a low-back stretch and pelvic tilt exercise to stretch your low-back muscles:
4. Strengthen your core muscles, especially the abdominal muscles, by incorporating planks into your routine:
5. Strengthen hamstring muscles with single-leg glute bridges: