The Butt Wink describes the portion of the pelvis when it moves into Posterior Pelvic Position, Loading the lower spine (Lumber) into Spinal Flexion. This can put additional pressure on muscles that stabilise the spine and pelvis, such as your iliopsoas (inner hip muscle), and vertebra disks. There are a few causes of the Butt Wink. Poor Ankle Mobility, Poor Technique, Poor Core Stability Control Poor Hip Range of Movement
If you’re currently experiencing Lower Back Pain due to posterior tilt of the pelvis I would suggest the following: Assessing your ankle/calf mobility, Seek out a great trainer to fix your technique Check your Core Stability by performing a BodyWeight Squat and a Squat holding a weight in front of you. If your squat with the weight are considerably better you have an issue with engaging your core to stabilise the body in the squat. Work to increase both External and Internal Hip Range.