Running is a full-body activity, and the faster you run, the more of your body you use. There are close to 700 muscles in the human body, and you use most of them when running fast. If you do all of your training at a slow pace as many long-distance runners do, you do not train the majority of your muscles, and you miss the opportunity to get faster.
There are three types of muscle fibers; slow-twitch, Intermediate fast-twitch, and fast-twitch. At low intensities, you only use your slow-twitch, and as the workout gets more intense, you start to include your intermediate and then fast-twitch fibers. Pete Magill in Fast 5K suggests that you need to vary your runnings paces to train each type of muscle fibre and reach your maximum running potential.
Jack Daniels suggests that you need to train using five specific paces relative to your V02Max. Daniels provides an online running calculator to work out these paces based on your most recent race performance.
| Training intensity | percentage of V02Max | Pace based on 1:35 1/2 marathon |
| Easy | 59-75% | 5:18-5:50 min/km |
| Marathon | 75-84% | 4:41 min/km |
| Threshold | 83-88% | 4:24 min/km |
| Interval | 95-100% | 4:03 min/km |
| Repetition | 100%+ | 3:48 min/km |
If you miss any of these five paces from running training, you leave gains in speed on the table. Start to build in all five paces into your running to get faster and wait till eight weeks before any race to start introducing specific workouts targeted at that event.
SamuelJTanner 