When analyzing a runner's training log one thing that usually jumps out at me is what's missing. I look for gaps.One gap that is very common is speed. And with good reason – it requires knowledge to do it correctly and it's easy to get hurt!

By far, one of the biggest differences between well-trained runners and wannabes is the competency at a variety of paces. Just like your favorite road bike has lots of different gears to optimize your effort and pace, so should you as a runner.

What does an effective speed workout for distance runners look like? What ingredients should you include so that you reap the most benefit for the time you're spending?