It seems pretty simple: right leg, left leg … but if you want to run fast, you need to develop strength and power in your running muscles. Try the following exercises if your goal is to run faster. And don't forget to stretch after your runs to minimize your risk for injury.
Runner's lunges: Turn your back to a chair or bench and then balance your right leg on it. Keeping your left knee over your ankle, slowly lower your right knee toward the ground. Take about one second to lower and one second to raise. Continue for 30 seconds and build up to 60-120 seconds as you develop your endurance.
Resisted lunge:Stand with one leg positioned in front of the other leg with an exercise tube positioned under the front foot while holding the handles at your shoulders. Keep the front knee over top of the ankle. Keep the back knee underneath or slightly behind your hips. Slowly lower the back knee toward the ground, keeping the front knee over the top the ankle the entire time. Only lower as low as you feel comfortable; the lowest point should be when your knee is at a 90-degree angle or your upper thigh is parallel to the ground. Keep your body weight positioned over the front leg -- this is your working leg. Return to the starting position and push right off the back foot -- balance for 1-2 seconds on the supporting leg and then repeat the exercise. Continue for 30 seconds each leg and then build to 2 minutes.
Exercuff knee drives: Wrap an exercuff around your ankles. Stand tall while keeping your abdominals contracted and your back in a neutral position. Begin the exercise by lifting your knee upward with strong power and speed. Alternate knee lifts and continue for 30 seconds and then build to 2 minutes.
You can purchase exercise tubing at your local department store like Target or Sports Authority.