interval training for better results
Doing intervals is the most important part of training speed. It requires good general fitness and foot strike. Keep focus on the aim of your interval training. A typical mistake is to run too fast during short repeats, since having strength enough is rarely a problem, and distances are relatively short. Training intensity should increase gradually to prepare the body for harder routines.
The central components of successful interval training are the right technique, mobility and speed. In the initial stages of your training schedule (base 1), intervals may be e.g. 6x5min at 85% maximum heart rate + 3min recovery at 60%. At this stage, repeats shouldn't be too long to make sure your speed remains adequate. As your endurance improves, repeats during speed work may be up to 20 minutes long (80-90% maximum heart rate). Maximum endurance is generally improved through interval training, as well, and is aimed specifically at enhancing performance. Running faster during the latter part of sessions is important during maximum endurance work (e.g. 5x3min at approx 90% + 5 min recovery).
You learn to pace yourself during interval training, since you run faster doing intervals than you would during the targeted event, like a marathon. Increasing your speed reserve is also important to make sure your running technique remains comfortable. Moreover, interval work improves recovery time, important for running on uneven terrain.