We hear about Core Training quite a bit anymore, and how it will benefit our training and performances. One of the most specific core and pre-habilitative exercises that triathletes should do are, "Seated Straight Leg Raises". I have include a short video clip to demonstrate.
These exercises will help maintain the proper patellar alignment as you extend your knee or load your leg. By locking out your knee you fire the Vastus Medialis Muscle (the Quadracep muscle on the inside of the knee). Too often the Vastus Lateralis (the Quadracep on the outside of the thigh) gets over developed and puts lateral pull on the patella causing it to move outside its favored groove. This exercise will help prevent that from happening by strengthening the Vastus Medialus and your core at the same time.
"It doesn't matter whether it is hot or cold, rainy or sunny, paths in the forest, asphalt in the streets; you must run until the question of running just never arises anymore than not eating or not sleeping".