Long Slow Distance Run (Run LSD)
The Long Slow Distance run is the Monday cardio session in the 26-week NSW preparation program. It is a continuous run at a low to moderate intensity, and it is the session that carries the largest distance progression in the whole plan, growing from 3 miles in week 1 to 9.25 miles in week 26.
How the Session Is Defined
The guide defines LSD work by feel rather than by a clock. Your pace should feel relatively easy and relaxed, and the check is the Talk Test: you should be able to speak in short sentences while running, drawing a breath between phrases. If you cannot speak, the pace is too fast. If you can speak without pause, the pace is too slow. The emphasis is duration over intensity. The LSD run builds endurance and gives the body relative recovery between the harder CHI and interval days. A warm-up of 5 to 10 minutes of easy jogging comes first, and the run should finish at a slightly faster pace than it started.
How It Progresses Across 26 Weeks
The LSD run adds a quarter mile every week without exception. Week 1 prescribes 3 miles, week 2 prescribes 3.25 miles, and the distance climbs in 0.25-mile steps through 4.25 miles in week 6, 5.75 miles in week 12, 7.25 miles in week 18, and 9.25 miles in week 26. The step is small, but the cumulative effect is large: the final run is more than three times the first. The guide allows a fitter candidate to skip ahead and begin at a later week, for example the 5-mile run of week 9, but CHI and interval sessions should still start at week 1.
Where It Sits in the Week and How to Pace It
Run LSD is fixed on Monday, paired with an upper-body and core strength session. It is the first hard-ground cardio of the week, and it comes two days before the Wednesday interval run and four days before the Friday CHI run, so the slow pace matters. Running the LSD too fast turns Monday into a third intense day and steals recovery from the sessions that build speed. Hold the conversational pace, keep the effort even, and let the distance do the work. If you have more than 26 weeks, the guide suggests adding LSD volume rather than increasing CHI or interval loads.
Progression across the program
| Week | Prescription |
|---|---|
| 1 | 3 miles |
| 6 | 4.25 miles |
| 12 | 5.75 miles |
| 18 | 7.25 miles |
| 26 | 9.25 miles |
Run the LSD on soft sand or trail when you can. BUD/S runs happen on the beach, and the easy pace makes Monday the safest day to condition your calves and ankles for it.
Related Terms
Long Slow Distance (LSD) training is a cardio methodology that emphasizes sustained, moderate-intensity effort over extended durations. In BUD/S preparation, LSD sessions build the aerobic base required for long swims, runs, and the prolonged physical output demanded throughout SEAL selection.
The Continuous High Intensity run is the Friday cardio session in the 26-week NSW preparation program. It is a sustained run at roughly 90 to 95 percent of the fastest pace you could hold for the prescribed time, with no rest inside the effort, and it grows from a single 15-minute block in week 1 to two 20-minute blocks in week 26.
The Interval run is the Wednesday cardio session in the 26-week NSW preparation program. It consists of repeated quarter-mile efforts at a pace slightly faster than your current 1.5-mile run pace, separated by recovery periods, and the number of repeats grows from 4 in week 1 to 10 by week 13.
The 1.5-mile run is the final event of the Physical Screening Test (PST) and measures a candidate's running speed and cardiovascular endurance. Performed after the swim and calisthenics events, it tests the ability to produce a fast run effort on fatigued legs — a skill directly relevant to BUD/S demands.
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