The common belief is that running or walking keeps your legs strong. While running and walking are great activities for your cardiovascular health, they are not the best form of exercise to build strength in your legs; strength training is. Building strong legs is the foundation to building a strong body just as building a solid foundation on a building is key having a strong structure.
Strength training develops your legs by forcing them to adapt to a resistance greater than your body weight. Consequently, your body responds by recruiting more muscle fibers to move the additional load resulting in an increase is muscle strength not only in your legs but all over your body. In addition strength training your legs causes your body to produce more testosterone and growth hormone.
Now that you see how important that having strong legs is, below is one of my favorite exercises for developing your legs.
You can find my complete strength training routines at Forever Fit and Firm