Drape a chain over your foot or put an ankle weight on and do a knee raise. Raise your knee until it’s waist height and lower it slowly. Don’t hang on to anything.
These are usually a high rep move towards the end of a workout or could even be done as a warm up to help bring blood to the hips and loosen tight hip flexors. 3-4 x 20-30
We did a hip flexor or an adductor movement 1x/ week and had almost no injuries in these areas.