Generally at structural level, anterior (or posterior) femur head have the priority, then TFL/ITB/adductors fascial restriction, ankle subluxation (chiro subluxation), sacroiliac joint subluxation, sacral torsion, low back or generic spinal fixations, need ortothics, malocclusion problems can be a cause of recurrent tightness.
Supplement and Arnica cream can be usefull for coadiuvate therapy and help with recovery.
A good acupuncturist can work on specific meridian pathway to release muscle tension and restore proper energy balance.
A progressive hip joint mobilization help a lot.