This is one of many ways to approach splits and oversplits. It’s also a helpful video to just target hamstring flexibility–you can skip the splits part if you like.

What’s happening in splits?

• Front leg: hamstrings are lengthened. Quads are gently engaged, periodically strengthening further (still gently) and relaxing. Gluteus maximus (main booty) stretches and gluteus medius (side butt) stabilizes. Hip draws back slightly to access the hamstrings (this is intense, be careful).
• Back leg: Dropping down into the frontal hip/upper thigh. Rotate this hip downward as if sinking toward the outer edge of the mat while the opposite hip opposes this action. Hip flexors are lengthened. Hamstrings are gently engaged. Front ankle receives a stretch while also building strength by resisting the ground. Hip draws forward slightly to access front hamstrings (please approach carefully)
• Feet: gently pointed; dorsiflexion on the front leg can aggravate the sciatic nerve. Tucking the toes under on the back foot and lifting gently is an optional alternative that facilitates strengthening. 
• Arms: stabilizing on the ground or on blocks, gently lifting and lowering torso periodically. 
• Spine: upright, hip position will bring some curve to the lumbar (low) spine.
• Lungs: expanding beyond their default range, slower rate. 
• Face: soft, if it scrunches (and you’re not being dramatic for entertainment purposes), it’s a sign–come out of the pose a little bit.

This video emphasizes hamstrings more than hip flexors so feel free to add in hip flexor stretches if you feel the need.

Remember to approach your splits in a healthy fashion. Take your time, practice patience, respect your limits as you inquire into them, and enjoy your developing body awareness 🙂