Every athlete wants to run faster and sustain speed over a period of time. However, many athletes simply don't understand how to achieve this goal.
It's common for runners to train at a comfortable jogging pace, one that can be sustained without rest, especially when preparing for long runs, like half or full marathons. However, training at a slow pace for a long period of time is not an effective way to build speed. It trains the body to do exactly that—run at a slow pace—which is undesirable.
There is a common misconception that simply increasing training volume or mileage alone will improve speed. It's true that new runners can get faster as a byproduct of fitness gains, but eventually speed gains will plateau. Increasing volume alone will not lead to more efficient and faster running over the long term, or in experienced runners with a good level of fitness.
Two components are critical to get faster: the nervous system and aerobic capacity.
The central nervous system is primarily responsible for controlling movement. The more effective it is, the faster you will be able to run. You can only move as fast as your nervous system permits—i.e., how well it communicates with your muscles to physically move your body. Training your nervous system allows your body greater control over movement, thus facilitating faster movement.
To train the nervous system, you must perform workouts that are explosive in nature, with a focus on short intervals and maximum intensity. The goal is to enable your nervous system to improve its control over fast movement.
A great way to train the nervous system is to perform short sprints at maximum effort. Do this for 10 to 15 seconds, then rest up to 90 seconds. Start by repeating four times and gradually increase the number of repeats over subsequent weeks as you improve. To increase the difficulty, perform the same workout on a hill. (Learn triathlete Chris Legh's Hill Repeats.)
Aerobic capacity is simply the maximum amount of oxygen the body can use during exercise. When you run at a medium pace, your body uses oxygen effectively via the aerobic system to fuel your activity and maintain the demand placed upon it. As you increase the intensity, you reach a point where your body can no longer keep up with the demand for oxygen to fuel the activity. This triggers the anaerobic system (which does not require oxygen), leading to lactic acid production and fatigue.
Developing your aerobic system will allow you to run at a faster pace before you reach this point. To develop your aerobic system, try a progression run: begin at a comfortable pace and gradually work up to a pace that taxes your aerobic system and eventually introduces the anaerobic system. This will train your body to be more efficient, delaying the onset of lactic acid production. For example, consider a 10-mile run. Begin at a comfortable pace and gradually speed up in intervals of 10 to 15 seconds per mile. Aim to finish the last mile at your race pace goal, or even slightly faster.
Take your speed work further by learning how to train for different types of speed.