When many runners train, they focus on running fast with breaks that are little to none, and then running fast again. A writer from Outside Magazine commented that runners may benefit from adding in occasional speed intervals in order to improve time. An easy way to add this to your routine is to perform several accelerations during your run for around 100m. Next, move on to alternating between running and jogging at different intervals. This allows you to practice running while your legs are tired, and it also improves your endurance.
The Crossroads of Special Operations