You need to stretch your inner thighs.
Why this matters:
One area that often gets overlooked is the inner thigh. It consists of our hip adductors and hip extensors (part of the hamstrings). Society says that you need to sit with your knees together. However, hold this position for too long and the inner thighs become tight, to the point where the hips can lock up. Not having enough hip motion results in the pelvis and low back to move too much. We can solve this problem by adding in some controlled closed chain movement in the hip.
Action steps:The inner thigh can be opened up via a side lunge stretch like this. Focus on maintaining a stable spine (not too flexed or extended), and as a result, you’ll feel a great opening of the hip. I recommend 10-15 pulses per side.