In addition to Good Form Running, here is more information regarding proper running form.
Leaning too far forward when you run can cause lower- back pain, neck and shoulder fatigue, and side stitches--all of which will cause you to slow down or increase your effort unnecessarily. This two-part drill will help you maintain the ideal upright position. Try it at the beginning of each run, when you resume running after a walk break, or whenever you begin to tire during a workout.
Head Position: How you hold your head is key to overall posture, which determines how efficiently you run. Let your gaze guide you. Look ahead naturally, not down at your feet, and scan the horizon. This will straighten your neck and back, and bring them into alignment. Don't allow your chin to jut out.
Shoulders: Shoulders play an important role in keeping your upper body relaxed while you run, which is critical to maintaining efficient running posture. Your shoulders should be low and loose, not high and tight. As you tire on a run, don't let them creep up toward your ears. If they do, shake them out to release the tension. Your shoulders also need to remain level and shouldn't dip from side to side with each stride.
Arms: Even though running is primarily a lower-body activity, your arms aren't just there for the heck of it. Your hands control the tension in your upper body, while your arm swing works in conjunction with your leg stride to drive you forward. Keep your hands in an unclenched fist, with your fingers lightly touching your palms. Imagine yourself trying to carry a potato chip in each hand without crushing it. Your arms should swing mostly forward and back, not across your body like Popeye, between waist and lower-chest level. Your elbows should be bent at about a 90- degree angle. When you feel your fists clenching or your forearms tensing, drop your arms to your sides and shake them out for a few seconds to release the tension.
Torso: The position of your torso while running is affected by the position of your head and shoulders. With your head up and looking ahead and your shoulders low and loose, your torso and back naturally straighten to allow you to run in an efficient, upright position that promotes breathing well and stride length. If you start to slouch during a run take a deep breath and feel yourself naturally straighten. As you exhale simply maintain that upright position.
Hips: Your hips are your center of gravity, so they're key to good running posture. The proper position of your torso while running helps to ensure your hips will also be in the ideal position. With your torso and back comfortably upright and straight, your hips naturally fall into proper alignment--pointing you straight ahead. If you allow your torso to hunch over or lean too far forward during a run, your pelvis will tilt forward as well, which can put pressure on your lower back and throw the rest of your lower body out of alignment. When trying to gauge the position of your hips, think of your pelvis as a bowl filled with marbles, then try not to spill the marbles by tilting the bowl.
Legs/Stride: While sprinters need to lift their knees high to achieve maximum leg power, distance runners don't need such an exaggerated knee lift--it's simply too hard to sustain for any length of time. Instead, endurance running requires just a slight knee lift, a quick leg turnover (how often your feet hit the ground), and a short stride (the space between your feet). Together, these will help you move forward without wasting energy. When running with the proper stride length, your feet should land directly underneath your body. As your foot strikes the ground, your knee should be slightly flexed so that it can bend naturally on impact. If your lower leg (below the knee) extends out in front of your body, your stride is too long.
When running, try to keep a conversational running pace. This means you should be able to talk while running. If you're gasping when you talk or having a hard time breathing, slow down. You should be able to talk but not sing :)