This is a public service announcement.
How do you get faster? In other words, how do you do you runs at a faster pace (for any given level of effort) and consequently have faster run times?
Let's think about what actually makes you run faster. There are two major components:
1) Training your biomechanical ability to run faster
If you want to run faster, well, your body needs to know how to run faster. You could slog 200mpw at 8:00/mile pace, but if that same person had to run 1 mile at 5:00/mile pace, he would find that very difficult to do. Why? Because his muscles, ligaments, tendons, supporting muscles, are not used to running at any pace other than 8:00/mile pace.
Therefore, you must incorporate faster running in order to develop running economy and efficiency of movement. In short, you need to develop muscle memory. The simplest way to do this is to incorporate strides into your running.
If you are a car, think of this as your platform. Your frame and wheelbase.
2) Training your cardiovascular system to run faster
Once your body has the muscle memory to run fast, you can develop your engine (heart), fuel injection/pump (blood vessels), your gas tank (mitochondria and energy conversion system), your axles (minor joints), your wheels and tires (legs), your radiator (body's cooling system).
You do this by introducing running at a variety of different paces. The more variety the better. Again, doing 200mpw at 8:00/mile pace will provide only one form of stress to your cardiovascular system. This leads to plateauing and is the slowest form of improvement. You need to introduce a variety of stimulus to promote a variety of biological and neuromuscular responses in your body. Very easy runs, easy runs, steady runs, steady-progressive runs, tempo runs, intervals, repetitions.
The ultimate goal is to increase the maximum speed at which you can run BEFORE you cross your lactate threshold. This is where you get the maximum amount of benefit as a distance runner. It is far better to run at a 6:00/mile pace aerobically than it is to do the same pace anaerobically. Why? Because you can maintain that pace longer, and your recovery will be easier.
Key Takeway:
1) Get your body biomechanically used to running fast by running fast
2) The most time-efficient way to increase your running pace is by using a wide variety of aerobic stimuli to increase the AVERAGE pace of your running for any given training cycle. Doing 100 miles in Week 1 at a combined average of 7:30/mile is going to provide a greater aerobic benefit than a combined average of 7:45/mile.
3) Doing the 7:30/mile average through a variety of running paces is more efficient than achieving the 7:30/mile average doing ALL of your running at 7:30/mile average.
4) The "variety" of aerobic paces promotes greater stimulus to your aerobic capacity (both structural like heart and lungs and local like capillaries and mitochondria), while also providing greater injury-prevention because you are combing fast running with slow easy running.
So to all your hobby joggers out there who want to get faster - don't be a fool and train like you're eating a 3-course meal prepared by VDOT. It's not just intervals, tempo and easy. There's a whole lot of paces within each of those categories that you need to be hitting for maximum benefit.