Run training should be performed in appropriate running shoes, not boots. If you can, seek advice from an experienced professional at an established running store, or a Sports Medicine professional. To increase your running speed and distance, you can do three types of training: long slow distance, continuous high intensity and intervals.
Long Slow Distance
The intensity of LSD work is low to moderate, so your pace should feel relatively easy and relaxed when doing these workouts. They build endurance and provide relative recovery between more intense sessions. To determine the appropriate intensity, use the Talk Test. You should be able to talk comfortably in short sentences or phrases while training, drawing breath between phrases.
If you can’t speak, you are working too hard, and if you can speak continually, you are not working hard enough. For LSD workouts, focus more on duration than intensity. If you are exceptionally fit, you might perform 40-90 minutes of continuous movement in one session. A practical goal to prepare for BUD/S is to build up to comfortably running 5-6 miles or swimming 1-1.25 miles without stopping.
Continuous High Intensity
Continuous High Intensity sessions typically involve moving for 15-20 minutes without stopping at a pace approximately 90-95 percent of the maximal pace you could hold for that duration.
The workout should be very demanding but not totally exhausting. On a scale of 1-10, with 10 being the greatest effort possible, the workout should feel like 8-9. If you are at a low fitness level, one repetition of 15-20 minutes is sufficient.
As your fitness improves, 2-3 repetitions may be required. When performing more than one repetition, allow sufficient recovery between repetitions so you can maintain the desired intensity of 90-95 percent of maximal pace. A reasonable recovery period is approximately half of the work time. During this time, keep moving at a low intensity – slow jog, brisk walk or easy stroke. Do not come to a complete stop.
These sessions alternate short, intense work intervals with periods of recovery. The format consists of running 1/4-mile intervals or swimming 100-yard intervals, allowing a recovery period of 2-2 1/2 times the amount of time it takes to perform the work interval.
Your intensity or pace should be slightly faster than the pace of your most recent 1.5-mile run or 500-yard swim.
For running, your 1/4-mile interval pace should initially be about 4 seconds faster than your base pace.
For example, if you recently completed a 1.5-mile run in 10:30 with a 1/4 mile base pace of 1:45 then your interval training pace should be about 1:41.
For swimming, your 100-yard interval pace should initially be 2 seconds fast than your base.
If you completed a 500-yard swim in 10:30 with a 100-yard base pace of 2:06 your intervals should be approximately 2:04.
If you have a low level of fitness, it may be necessary to begin with 4-5 intervals per session. Build progressively toward completing 8-10 intervals. Do not run or swim more than 10 intervals during an interval session.
When you can complete 10 intervals in the prescribed times, work on gradually performing the intervals a little faster each week. Work on consistency, trying to keep little variation between your fastest and slowest interval and pacing yourself to be fastest at the end of the workout.
Every 4th or 5th week, it may be beneficial to increase your intensity using shorter, more frequent intervals. For example, 16-20 x 220-yard running intervals or 16-20 x 50-yard swimming intervals. Allow enough recovery time to maintain the proper work intensity, without taking excessive time or wasting time. To promote faster, more complete recovery, use some active recovery, such as brisk walking, easy stroking or slow jogging for part of the time between intervals.