It has been proven in several studies that wearing a weighted vest while running will improve leg strength. That of course should increase running speed. Most of my experience with a weighted vest has been running intervals on a treadmill and doing exercises such as: chin-ups, push-ups, squats and crunches. Wow! what a workout. You can burn lots of calories, increase running speed and build lean muscle mass with one piece of equipment. Remember to use with caution. Never use one if you've had knee or back injuries. Don't risk getting reinjuried . Always start with light weights. And most importantly, make sure the vest fits properly.
Now the weight is on your shoulders! And that's how you keep it moving