The issue could be anything but it's just a strength imbalance and some tightness as a result of lack of strength training in certain positions and ranges of motion. All that means is that you need a workout routine that is for building athleticism and strength.
Most people have poor leg and hip development. Here is the program:
Here is the beginner routine in short:
- Walk backwards
- Shin lift
- Split squat (lunge)
In-depth: Knees Over Toes Guy's Beginner Workout
Programming involves 12 weeks of slowly developing strength and flexibility generally, so go ahead and spend 12 weeks on these three. You can do them daily and go by feel. No pain.
After reaching the standards in that video and progressing over 12 weeks go ahead and add these to your routine:
- Calf raises w/ flexion of tibialis anterior
- Incline hamstring stretch/Jefferson curl
- Bodyweight leg extensions (knee against wall stretch)
- Piriformus good mornings (Pigeon stretch)
- Loaded butterflies (Lying leg extended wall stretch)
- Wide leg loaded groin stretch (standing wide groin stretch)
- ATG Split Squat with weight
- Incline hip/oblique weighted raises
This is the video describing the exercises and strength standards to reach:
Knees Over Toes Guy's Mobility Checklist
After reaching 25% BW on the relevant exercises and/ or mobility and repetition goals with no pain go ahead and add the next exercises to your routine.
Add Nordic Curls and Foot Lifts.
10 Reasons to Lift Weights With Your Feet
Nordic Hamstring Curl Tutorial From The Standards Program
Make sure to watch all the videos.