Runners using the run/walk method can use a one-mile test known as the Magic Mile to estimate suitable training and race paces. The test offers a starting point for choosing intervals, though the recommended run/walk ratios can be adjusted to individual comfort and needs.
To complete the test, find a track or a flat one-mile route. Warm up with 10 minutes of easy running, followed by four 100-meter strides and three minutes of walking. Then run one mile at a consistent, natural effort, taking walk breaks if needed, and record the finishing time.
Galloway’s pace formulas use that Magic Mile time to estimate paces for longer distances: add 33 seconds for a 5K; multiply the mile time by 1.15 for a 10K, 1.175 for 10 miles, 1.2 for a half marathon, and 1.3 for a marathon. For long runs, the suggested target is about 90 seconds to two minutes slower than the estimated 5K pace.
The guide recommends repeating the test every one to three weeks to keep pace estimates aligned with current fitness. On a repeat, runners should begin more slowly than their previous effort, gradually increase speed, and finish strongly. A slower result is not necessarily cause for concern: sleep, stress, the need for rest or cross-training, and training choices can all affect performance.
For weekly training, the guide suggests a tempo run at marathon pace, experimenting with different run/walk splits. Example ratios include running for six minutes and walking for 30 seconds at a predicted seven-minute mile pace; four minutes and 30 seconds at an eight-minute pace; two minutes and 30 seconds at a nine-minute pace; 90 seconds and 30 seconds at a 10-minute pace; and 60 seconds and 30 seconds at an 11-minute pace. These are guidelines, not fixed rules.
The Magic Mile can inform training and race planning, but it does not guarantee a race result. Chris Twiggs, chief training officer at Galloway Training, says some runners he has coached have raced faster than their Magic Mile predicted.
Sources: Runner's World.